text: /*
   * copyright (c) 2001 Fabrice Bellard
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #ifndef AVCODEC_AVCODEC_H
  #define AVCODEC_AVCODEC_H
  
  /**
   * @file
   * @ingroup libavc
   * Libavcodec external API header
   */
  
  #include <errno.h>
  #include "libavutil/samplefmt.h"
  #include "libavutil/attributes.h"
  #include "libavutil/avutil.h"
  #include "libavutil/buffer.h"
  #include "libavutil/cpu.h"
  #include "libavutil/channel_layout.h"
  #include "libavutil/dict.h"
  #include "libavutil/frame.h"
  #include "libavutil/log.h"
  #include "libavutil/pixfmt.h"
  #include "libavutil/rational.h"
  
  #include "version.h"
  
  /**
   * @defgroup libavc Encoding/Decoding Library
   * @{
   *
   * @defgroup lavc_decoding Decoding
   * @{
   * @}
   *
   * @defgroup lavc_encoding Encoding
   * @{
   * @}
   *
   * @defgroup lavc_codec Codecs
   * @{
   * @defgroup lavc_codec_native Native Codecs
   * @{
   * @}
   * @defgroup lavc_codec_wrappers External library wrappers
   * @{
   * @}
   * @defgroup lavc_codec_hwaccel Hardware Accelerators bridge
   * @{
   * @}
   * @}
   * @defgroup lavc_internal Internal
   * @{
   * @}
   * @}
   *
   */
  
  /**
   * @defgroup lavc_core Core functions/structures.
   * @ingroup libavc
   *
   * Basic definitions, functions for querying libavcodec capabilities,
   * allocating core structures, etc.
   * @{
   */
  
  
  /**
   * Identify the syntax and semantics of the bitstream.
   * The principle is roughly:
   * Two decoders with the same ID can decode the same streams.
   * Two encoders with the same ID can encode compatible streams.
   * There may be slight deviations from the principle due to implementation
   * details.
   *
   * If you add a codec ID to this list, add it so that
   * 1. no value of a existing codec ID changes (that would break ABI),
   * 2. Give it a value which when taken as ASCII is recognized uniquely by a human as this specific codec.
   *    This ensures that 2 forks can independently add AVCodecIDs without producing conflicts.
   *
   * After adding new codec IDs, do not forget to add an entry to the codec
   * descriptor list and bump libavcodec minor version.
   */
  enum AVCodecID {
      AV_CODEC_ID_NONE,
  
      /* video codecs */
      AV_CODEC_ID_MPEG1VIDEO,
      AV_CODEC_ID_MPEG2VIDEO, ///< preferred ID for MPEG-1/2 video decoding
  #if FF_API_XVMC
      AV_CODEC_ID_MPEG2VIDEO_XVMC,
  #endif /* FF_API_XVMC */
      AV_CODEC_ID_H261,
      AV_CODEC_ID_H263,
      AV_CODEC_ID_RV10,
      AV_CODEC_ID_RV20,
      AV_CODEC_ID_MJPEG,
      AV_CODEC_ID_MJPEGB,
      AV_CODEC_ID_LJPEG,
      AV_CODEC_ID_SP5X,
      AV_CODEC_ID_JPEGLS,
      AV_CODEC_ID_MPEG4,
      AV_CODEC_ID_RAWVIDEO,
      AV_CODEC_ID_MSMPEG4V1,
      AV_CODEC_ID_MSMPEG4V2,
      AV_CODEC_ID_MSMPEG4V3,
      AV_CODEC_ID_WMV1,
      AV_CODEC_ID_WMV2,
      AV_CODEC_ID_H263P,
      AV_CODEC_ID_H263I,
      AV_CODEC_ID_FLV1,
      AV_CODEC_ID_SVQ1,
      AV_CODEC_ID_SVQ3,
      AV_CODEC_ID_DVVIDEO,
      AV_CODEC_ID_HUFFYUV,
      AV_CODEC_ID_CYUV,
      AV_CODEC_ID_H264,
      AV_CODEC_ID_INDEO3,
      AV_CODEC_ID_VP3,
      AV_CODEC_ID_THEORA,
      AV_CODEC_ID_ASV1,
      AV_CODEC_ID_ASV2,
      AV_CODEC_ID_FFV1,
      AV_CODEC_ID_4XM,
      AV_CODEC_ID_VCR1,
      AV_CODEC_ID_CLJR,
      AV_CODEC_ID_MDEC,
      AV_CODEC_ID_ROQ,
      AV_CODEC_ID_INTERPLAY_VIDEO,
      AV_CODEC_ID_XAN_WC3,
      AV_CODEC_ID_XAN_WC4,
      AV_CODEC_ID_RPZA,
      AV_CODEC_ID_CINEPAK,
      AV_CODEC_ID_WS_VQA,
      AV_CODEC_ID_MSRLE,
      AV_CODEC_ID_MSVIDEO1,
      AV_CODEC_ID_IDCIN,
      AV_CODEC_ID_8BPS,
      AV_CODEC_ID_SMC,
      AV_CODEC_ID_FLIC,
      AV_CODEC_ID_TRUEMOTION1,
      AV_CODEC_ID_VMDVIDEO,
      AV_CODEC_ID_MSZH,
      AV_CODEC_ID_ZLIB,
      AV_CODEC_ID_QTRLE,
      AV_CODEC_ID_TSCC,
      AV_CODEC_ID_ULTI,
      AV_CODEC_ID_QDRAW,
      AV_CODEC_ID_VIXL,
      AV_CODEC_ID_QPEG,
      AV_CODEC_ID_PNG,
      AV_CODEC_ID_PPM,
      AV_CODEC_ID_PBM,
      AV_CODEC_ID_PGM,
      AV_CODEC_ID_PGMYUV,
      AV_CODEC_ID_PAM,
      AV_CODEC_ID_FFVHUFF,
      AV_CODEC_ID_RV30,
      AV_CODEC_ID_RV40,
      AV_CODEC_ID_VC1,
      AV_CODEC_ID_WMV3,
      AV_CODEC_ID_LOCO,
      AV_CODEC_ID_WNV1,
      AV_CODEC_ID_AASC,
      AV_CODEC_ID_INDEO2,
      AV_CODEC_ID_FRAPS,
      AV_CODEC_ID_TRUEMOTION2,
      AV_CODEC_ID_BMP,
      AV_CODEC_ID_CSCD,
      AV_CODEC_ID_MMVIDEO,
      AV_CODEC_ID_ZMBV,
      AV_CODEC_ID_AVS,
      AV_CODEC_ID_SMACKVIDEO,
      AV_CODEC_ID_NUV,
      AV_CODEC_ID_KMVC,
      AV_CODEC_ID_FLASHSV,
      AV_CODEC_ID_CAVS,
      AV_CODEC_ID_JPEG2000,
      AV_CODEC_ID_VMNC,
      AV_CODEC_ID_VP5,
      AV_CODEC_ID_VP6,
      AV_CODEC_ID_VP6F,
      AV_CODEC_ID_TARGA,
      AV_CODEC_ID_DSICINVIDEO,
      AV_CODEC_ID_TIERTEXSEQVIDEO,
      AV_CODEC_ID_TIFF,
      AV_CODEC_ID_GIF,
      AV_CODEC_ID_DXA,
      AV_CODEC_ID_DNXHD,
      AV_CODEC_ID_THP,
      AV_CODEC_ID_SGI,
      AV_CODEC_ID_C93,
      AV_CODEC_ID_BETHSOFTVID,
      AV_CODEC_ID_PTX,
      AV_CODEC_ID_TXD,
      AV_CODEC_ID_VP6A,
      AV_CODEC_ID_AMV,
      AV_CODEC_ID_VB,
      AV_CODEC_ID_PCX,
      AV_CODEC_ID_SUNRAST,
      AV_CODEC_ID_INDEO4,
      AV_CODEC_ID_INDEO5,
      AV_CODEC_ID_MIMIC,
      AV_CODEC_ID_RL2,
      AV_CODEC_ID_ESCAPE124,
      AV_CODEC_ID_DIRAC,
      AV_CODEC_ID_BFI,
      AV_CODEC_ID_CMV,
      AV_CODEC_ID_MOTIONPIXELS,
      AV_CODEC_ID_TGV,
      AV_CODEC_ID_TGQ,
      AV_CODEC_ID_TQI,
      AV_CODEC_ID_AURA,
      AV_CODEC_ID_AURA2,
      AV_CODEC_ID_V210X,
      AV_CODEC_ID_TMV,
      AV_CODEC_ID_V210,
      AV_CODEC_ID_DPX,
      AV_CODEC_ID_MAD,
      AV_CODEC_ID_FRWU,
      AV_CODEC_ID_FLASHSV2,
      AV_CODEC_ID_CDGRAPHICS,
      AV_CODEC_ID_R210,
      AV_CODEC_ID_ANM,
      AV_CODEC_ID_BINKVIDEO,
      AV_CODEC_ID_IFF_ILBM,
      AV_CODEC_ID_IFF_BYTERUN1,
      AV_CODEC_ID_KGV1,
      AV_CODEC_ID_YOP,
      AV_CODEC_ID_VP8,
      AV_CODEC_ID_PICTOR,
      AV_CODEC_ID_ANSI,
      AV_CODEC_ID_A64_MULTI,
      AV_CODEC_ID_A64_MULTI5,
      AV_CODEC_ID_R10K,
      AV_CODEC_ID_MXPEG,
      AV_CODEC_ID_LAGARITH,
      AV_CODEC_ID_PRORES,
      AV_CODEC_ID_JV,
      AV_CODEC_ID_DFA,
      AV_CODEC_ID_WMV3IMAGE,
      AV_CODEC_ID_VC1IMAGE,
      AV_CODEC_ID_UTVIDEO,
      AV_CODEC_ID_BMV_VIDEO,
      AV_CODEC_ID_VBLE,
      AV_CODEC_ID_DXTORY,
      AV_CODEC_ID_V410,
      AV_CODEC_ID_XWD,
      AV_CODEC_ID_CDXL,
      AV_CODEC_ID_XBM,
      AV_CODEC_ID_ZEROCODEC,
      AV_CODEC_ID_MSS1,
      AV_CODEC_ID_MSA1,
      AV_CODEC_ID_TSCC2,
      AV_CODEC_ID_MTS2,
      AV_CODEC_ID_CLLC,
      AV_CODEC_ID_MSS2,
      AV_CODEC_ID_VP9,
      AV_CODEC_ID_AIC,
      AV_CODEC_ID_ESCAPE130_DEPRECATED,
      AV_CODEC_ID_G2M_DEPRECATED,
      AV_CODEC_ID_WEBP_DEPRECATED,
      AV_CODEC_ID_HNM4_VIDEO,
      AV_CODEC_ID_HEVC_DEPRECATED,
      AV_CODEC_ID_FIC,
      AV_CODEC_ID_ALIAS_PIX,
      AV_CODEC_ID_BRENDER_PIX_DEPRECATED,
      AV_CODEC_ID_PAF_VIDEO_DEPRECATED,
      AV_CODEC_ID_EXR_DEPRECATED,
      AV_CODEC_ID_VP7_DEPRECATED,
      AV_CODEC_ID_SANM_DEPRECATED,
      AV_CODEC_ID_SGIRLE_DEPRECATED,
      AV_CODEC_ID_MVC1_DEPRECATED,
      AV_CODEC_ID_MVC2_DEPRECATED,
  
      AV_CODEC_ID_BRENDER_PIX= MKBETAG('B','P','I','X'),
      AV_CODEC_ID_Y41P       = MKBETAG('Y','4','1','P'),
      AV_CODEC_ID_ESCAPE130  = MKBETAG('E','1','3','0'),
      AV_CODEC_ID_EXR        = MKBETAG('0','E','X','R'),
      AV_CODEC_ID_AVRP       = MKBETAG('A','V','R','P'),
  
      AV_CODEC_ID_012V       = MKBETAG('0','1','2','V'),
      AV_CODEC_ID_G2M        = MKBETAG( 0 ,'G','2','M'),
      AV_CODEC_ID_AVUI       = MKBETAG('A','V','U','I'),
      AV_CODEC_ID_AYUV       = MKBETAG('A','Y','U','V'),
      AV_CODEC_ID_TARGA_Y216 = MKBETAG('T','2','1','6'),
      AV_CODEC_ID_V308       = MKBETAG('V','3','0','8'),
      AV_CODEC_ID_V408       = MKBETAG('V','4','0','8'),
      AV_CODEC_ID_YUV4       = MKBETAG('Y','U','V','4'),
      AV_CODEC_ID_SANM       = MKBETAG('S','A','N','M'),
      AV_CODEC_ID_PAF_VIDEO  = MKBETAG('P','A','F','V'),
      AV_CODEC_ID_AVRN       = MKBETAG('A','V','R','n'),
      AV_CODEC_ID_CPIA       = MKBETAG('C','P','I','A'),
      AV_CODEC_ID_XFACE      = MKBETAG('X','F','A','C'),
      AV_CODEC_ID_SGIRLE     = MKBETAG('S','G','I','R'),
      AV_CODEC_ID_MVC1       = MKBETAG('M','V','C','1'),
      AV_CODEC_ID_MVC2       = MKBETAG('M','V','C','2'),
      AV_CODEC_ID_SNOW       = MKBETAG('S','N','O','W'),
      AV_CODEC_ID_WEBP       = MKBETAG('W','E','B','P'),
      AV_CODEC_ID_SMVJPEG    = MKBETAG('S','M','V','J'),
      AV_CODEC_ID_HEVC       = MKBETAG('H','2','6','5'),
  #define AV_CODEC_ID_H265 AV_CODEC_ID_HEVC
      AV_CODEC_ID_VP7        = MKBETAG('V','P','7','0'),
      AV_CODEC_ID_APNG       = MKBETAG('A','P','N','G'),
  
      /* various PCM "codecs" */
      AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
      AV_CODEC_ID_PCM_S16LE = 0x10000,
      AV_CODEC_ID_PCM_S16BE,
      AV_CODEC_ID_PCM_U16LE,
      AV_CODEC_ID_PCM_U16BE,
      AV_CODEC_ID_PCM_S8,
      AV_CODEC_ID_PCM_U8,
      AV_CODEC_ID_PCM_MULAW,
      AV_CODEC_ID_PCM_ALAW,
      AV_CODEC_ID_PCM_S32LE,
      AV_CODEC_ID_PCM_S32BE,
      AV_CODEC_ID_PCM_U32LE,
      AV_CODEC_ID_PCM_U32BE,
      AV_CODEC_ID_PCM_S24LE,
      AV_CODEC_ID_PCM_S24BE,
      AV_CODEC_ID_PCM_U24LE,
      AV_CODEC_ID_PCM_U24BE,
      AV_CODEC_ID_PCM_S24DAUD,
      AV_CODEC_ID_PCM_ZORK,
      AV_CODEC_ID_PCM_S16LE_PLANAR,
      AV_CODEC_ID_PCM_DVD,
      AV_CODEC_ID_PCM_F32BE,
      AV_CODEC_ID_PCM_F32LE,
      AV_CODEC_ID_PCM_F64BE,
      AV_CODEC_ID_PCM_F64LE,
      AV_CODEC_ID_PCM_BLURAY,
      AV_CODEC_ID_PCM_LXF,
      AV_CODEC_ID_S302M,
      AV_CODEC_ID_PCM_S8_PLANAR,
      AV_CODEC_ID_PCM_S24LE_PLANAR_DEPRECATED,
      AV_CODEC_ID_PCM_S32LE_PLANAR_DEPRECATED,
      AV_CODEC_ID_PCM_S24LE_PLANAR = MKBETAG(24,'P','S','P'),
      AV_CODEC_ID_PCM_S32LE_PLANAR = MKBETAG(32,'P','S','P'),
      AV_CODEC_ID_PCM_S16BE_PLANAR = MKBETAG('P','S','P',16),
  
      /* various ADPCM codecs */
      AV_CODEC_ID_ADPCM_IMA_QT = 0x11000,
      AV_CODEC_ID_ADPCM_IMA_WAV,
      AV_CODEC_ID_ADPCM_IMA_DK3,
      AV_CODEC_ID_ADPCM_IMA_DK4,
      AV_CODEC_ID_ADPCM_IMA_WS,
      AV_CODEC_ID_ADPCM_IMA_SMJPEG,
      AV_CODEC_ID_ADPCM_MS,
      AV_CODEC_ID_ADPCM_4XM,
      AV_CODEC_ID_ADPCM_XA,
      AV_CODEC_ID_ADPCM_ADX,
      AV_CODEC_ID_ADPCM_EA,
      AV_CODEC_ID_ADPCM_G726,
      AV_CODEC_ID_ADPCM_CT,
      AV_CODEC_ID_ADPCM_SWF,
      AV_CODEC_ID_ADPCM_YAMAHA,
      AV_CODEC_ID_ADPCM_SBPRO_4,
      AV_CODEC_ID_ADPCM_SBPRO_3,
      AV_CODEC_ID_ADPCM_SBPRO_2,
      AV_CODEC_ID_ADPCM_THP,
      AV_CODEC_ID_ADPCM_IMA_AMV,
      AV_CODEC_ID_ADPCM_EA_R1,
      AV_CODEC_ID_ADPCM_EA_R3,
      AV_CODEC_ID_ADPCM_EA_R2,
      AV_CODEC_ID_ADPCM_IMA_EA_SEAD,
      AV_CODEC_ID_ADPCM_IMA_EA_EACS,
      AV_CODEC_ID_ADPCM_EA_XAS,
      AV_CODEC_ID_ADPCM_EA_MAXIS_XA,
      AV_CODEC_ID_ADPCM_IMA_ISS,
      AV_CODEC_ID_ADPCM_G722,
      AV_CODEC_ID_ADPCM_IMA_APC,
      AV_CODEC_ID_ADPCM_VIMA_DEPRECATED,
      AV_CODEC_ID_ADPCM_VIMA = MKBETAG('V','I','M','A'),
      AV_CODEC_ID_VIMA       = MKBETAG('V','I','M','A'),
      AV_CODEC_ID_ADPCM_AFC  = MKBETAG('A','F','C',' '),
      AV_CODEC_ID_ADPCM_IMA_OKI = MKBETAG('O','K','I',' '),
      AV_CODEC_ID_ADPCM_DTK  = MKBETAG('D','T','K',' '),
      AV_CODEC_ID_ADPCM_IMA_RAD = MKBETAG('R','A','D',' '),
      AV_CODEC_ID_ADPCM_G726LE = MKBETAG('6','2','7','G'),
  
      /* AMR */
      AV_CODEC_ID_AMR_NB = 0x12000,
      AV_CODEC_ID_AMR_WB,
  
      /* RealAudio codecs*/
      AV_CODEC_ID_RA_144 = 0x13000,
      AV_CODEC_ID_RA_288,
  
      /* various DPCM codecs */
      AV_CODEC_ID_ROQ_DPCM = 0x14000,
      AV_CODEC_ID_INTERPLAY_DPCM,
      AV_CODEC_ID_XAN_DPCM,
      AV_CODEC_ID_SOL_DPCM,
  
      /* audio codecs */
      AV_CODEC_ID_MP2 = 0x15000,
      AV_CODEC_ID_MP3, ///< preferred ID for decoding MPEG audio layer 1, 2 or 3
      AV_CODEC_ID_AAC,
      AV_CODEC_ID_AC3,
      AV_CODEC_ID_DTS,
      AV_CODEC_ID_VORBIS,
      AV_CODEC_ID_DVAUDIO,
      AV_CODEC_ID_WMAV1,
      AV_CODEC_ID_WMAV2,
      AV_CODEC_ID_MACE3,
      AV_CODEC_ID_MACE6,
      AV_CODEC_ID_VMDAUDIO,
      AV_CODEC_ID_FLAC,
      AV_CODEC_ID_MP3ADU,
      AV_CODEC_ID_MP3ON4,
      AV_CODEC_ID_SHORTEN,
      AV_CODEC_ID_ALAC,
      AV_CODEC_ID_WESTWOOD_SND1,
      AV_CODEC_ID_GSM, ///< as in Berlin toast format
      AV_CODEC_ID_QDM2,
      AV_CODEC_ID_COOK,
      AV_CODEC_ID_TRUESPEECH,
      AV_CODEC_ID_TTA,
      AV_CODEC_ID_SMACKAUDIO,
      AV_CODEC_ID_QCELP,
      AV_CODEC_ID_WAVPACK,
      AV_CODEC_ID_DSICINAUDIO,
      AV_CODEC_ID_IMC,
      AV_CODEC_ID_MUSEPACK7,
      AV_CODEC_ID_MLP,
      AV_CODEC_ID_GSM_MS, /* as found in WAV */
      AV_CODEC_ID_ATRAC3,
  #if FF_API_VOXWARE
      AV_CODEC_ID_VOXWARE,
  #endif
      AV_CODEC_ID_APE,
      AV_CODEC_ID_NELLYMOSER,
      AV_CODEC_ID_MUSEPACK8,
      AV_CODEC_ID_SPEEX,
      AV_CODEC_ID_WMAVOICE,
      AV_CODEC_ID_WMAPRO,
      AV_CODEC_ID_WMALOSSLESS,
      AV_CODEC_ID_ATRAC3P,
      AV_CODEC_ID_EAC3,
      AV_CODEC_ID_SIPR,
      AV_CODEC_ID_MP1,
      AV_CODEC_ID_TWINVQ,
      AV_CODEC_ID_TRUEHD,
      AV_CODEC_ID_MP4ALS,
      AV_CODEC_ID_ATRAC1,
      AV_CODEC_ID_BINKAUDIO_RDFT,
      AV_CODEC_ID_BINKAUDIO_DCT,
      AV_CODEC_ID_AAC_LATM,
      AV_CODEC_ID_QDMC,
      AV_CODEC_ID_CELT,
      AV_CODEC_ID_G723_1,
      AV_CODEC_ID_G729,
      AV_CODEC_ID_8SVX_EXP,
      AV_CODEC_ID_8SVX_FIB,
      AV_CODEC_ID_BMV_AUDIO,
      AV_CODEC_ID_RALF,
      AV_CODEC_ID_IAC,
      AV_CODEC_ID_ILBC,
      AV_CODEC_ID_OPUS_DEPRECATED,
      AV_CODEC_ID_COMFORT_NOISE,
      AV_CODEC_ID_TAK_DEPRECATED,
      AV_CODEC_ID_METASOUND,
      AV_CODEC_ID_PAF_AUDIO_DEPRECATED,
      AV_CODEC_ID_ON2AVC,
      AV_CODEC_ID_FFWAVESYNTH = MKBETAG('F','F','W','S'),
      AV_CODEC_ID_SONIC       = MKBETAG('S','O','N','C'),
      AV_CODEC_ID_SONIC_LS    = MKBETAG('S','O','N','L'),
      AV_CODEC_ID_PAF_AUDIO   = MKBETAG('P','A','F','A'),
      AV_CODEC_ID_OPUS        = MKBETAG('O','P','U','S'),
      AV_CODEC_ID_TAK         = MKBETAG('t','B','a','K'),
      AV_CODEC_ID_EVRC        = MKBETAG('s','e','v','c'),
      AV_CODEC_ID_SMV         = MKBETAG('s','s','m','v'),
      AV_CODEC_ID_DSD_LSBF    = MKBETAG('D','S','D','L'),
      AV_CODEC_ID_DSD_MSBF    = MKBETAG('D','S','D','M'),
      AV_CODEC_ID_DSD_LSBF_PLANAR = MKBETAG('D','S','D','1'),
      AV_CODEC_ID_DSD_MSBF_PLANAR = MKBETAG('D','S','D','8'),
  
      /* subtitle codecs */
      AV_CODEC_ID_FIRST_SUBTITLE = 0x17000,          ///< A dummy ID pointing at the start of subtitle codecs.
      AV_CODEC_ID_DVD_SUBTITLE = 0x17000,
      AV_CODEC_ID_DVB_SUBTITLE,
      AV_CODEC_ID_TEXT,  ///< raw UTF-8 text
      AV_CODEC_ID_XSUB,
      AV_CODEC_ID_SSA,
      AV_CODEC_ID_MOV_TEXT,
      AV_CODEC_ID_HDMV_PGS_SUBTITLE,
      AV_CODEC_ID_DVB_TELETEXT,
      AV_CODEC_ID_SRT,
      AV_CODEC_ID_MICRODVD   = MKBETAG('m','D','V','D'),
      AV_CODEC_ID_EIA_608    = MKBETAG('c','6','0','8'),
      AV_CODEC_ID_JACOSUB    = MKBETAG('J','S','U','B'),
      AV_CODEC_ID_SAMI       = MKBETAG('S','A','M','I'),
      AV_CODEC_ID_REALTEXT   = MKBETAG('R','T','X','T'),
      AV_CODEC_ID_STL        = MKBETAG('S','p','T','L'),
      AV_CODEC_ID_SUBVIEWER1 = MKBETAG('S','b','V','1'),
      AV_CODEC_ID_SUBVIEWER  = MKBETAG('S','u','b','V'),
      AV_CODEC_ID_SUBRIP     = MKBETAG('S','R','i','p'),
      AV_CODEC_ID_WEBVTT     = MKBETAG('W','V','T','T'),
      AV_CODEC_ID_MPL2       = MKBETAG('M','P','L','2'),
      AV_CODEC_ID_VPLAYER    = MKBETAG('V','P','l','r'),
      AV_CODEC_ID_PJS        = MKBETAG('P','h','J','S'),
      AV_CODEC_ID_ASS        = MKBETAG('A','S','S',' '),  ///< ASS as defined in Matroska
  
      /* other specific kind of codecs (generally used for attachments) */
      AV_CODEC_ID_FIRST_UNKNOWN = 0x18000,           ///< A dummy ID pointing at the start of various fake codecs.
      AV_CODEC_ID_TTF = 0x18000,
      AV_CODEC_ID_BINTEXT    = MKBETAG('B','T','X','T'),
      AV_CODEC_ID_XBIN       = MKBETAG('X','B','I','N'),
      AV_CODEC_ID_IDF        = MKBETAG( 0 ,'I','D','F'),
      AV_CODEC_ID_OTF        = MKBETAG( 0 ,'O','T','F'),
      AV_CODEC_ID_SMPTE_KLV  = MKBETAG('K','L','V','A'),
      AV_CODEC_ID_DVD_NAV    = MKBETAG('D','N','A','V'),
      AV_CODEC_ID_TIMED_ID3  = MKBETAG('T','I','D','3'),
      AV_CODEC_ID_BIN_DATA   = MKBETAG('D','A','T','A'),
  
  
      AV_CODEC_ID_PROBE = 0x19000, ///< codec_id is not known (like AV_CODEC_ID_NONE) but lavf should attempt to identify it
  
      AV_CODEC_ID_MPEG2TS = 0x20000, /**< _FAKE_ codec to indicate a raw MPEG-2 TS
                                  * stream (only used by libavformat) */
      AV_CODEC_ID_MPEG4SYSTEMS = 0x20001, /**< _FAKE_ codec to indicate a MPEG-4 Systems
                                  * stream (only used by libavformat) */
      AV_CODEC_ID_FFMETADATA = 0x21000,   ///< Dummy codec for streams containing only metadata information.
  
  #if FF_API_CODEC_ID
  #include "old_codec_ids.h"
  #endif
  };
  
  /**
   * This struct describes the properties of a single codec described by an
   * AVCodecID.
   * @see avcodec_descriptor_get()
   */
  typedef struct AVCodecDescriptor {
      enum AVCodecID     id;
      enum AVMediaType type;
      /**
       * Name of the codec described by this descriptor. It is non-empty and
       * unique for each codec descriptor. It should contain alphanumeric
       * characters and '_' only.
       */
      const char      *name;
      /**
       * A more descriptive name for this codec. May be NULL.
       */
      const char *long_name;
      /**
       * Codec properties, a combination of AV_CODEC_PROP_* flags.
       */
      int             props;
  
      /**
       * MIME type(s) associated with the codec.
       * May be NULL; if not, a NULL-terminated array of MIME types.
       * The first item is always non-NULL and is the preferred MIME type.
       */
      const char *const *mime_types;
  } AVCodecDescriptor;
  
  /**
   * Codec uses only intra compression.
   * Video codecs only.
   */
  #define AV_CODEC_PROP_INTRA_ONLY    (1 << 0)
  /**
   * Codec supports lossy compression. Audio and video codecs only.
   * @note a codec may support both lossy and lossless
   * compression modes
   */
  #define AV_CODEC_PROP_LOSSY         (1 << 1)
  /**
   * Codec supports lossless compression. Audio and video codecs only.
   */
  #define AV_CODEC_PROP_LOSSLESS      (1 << 2)
  /**
   * Codec supports frame reordering. That is, the coded order (the order in which
   * the encoded packets are output by the encoders / stored / input to the
   * decoders) may be different from the presentation order of the corresponding
   * frames.
   *
   * For codecs that do not have this property set, PTS and DTS should always be
   * equal.
   */
  #define AV_CODEC_PROP_REORDER       (1 << 3)
  /**
   * Subtitle codec is bitmap based
   * Decoded AVSubtitle data can be read from the AVSubtitleRect->pict field.
   */
  #define AV_CODEC_PROP_BITMAP_SUB    (1 << 16)
  /**
   * Subtitle codec is text based.
   * Decoded AVSubtitle data can be read from the AVSubtitleRect->ass field.
   */
  #define AV_CODEC_PROP_TEXT_SUB      (1 << 17)
  
  /**
   * @ingroup lavc_decoding
   * Required number of additionally allocated bytes at the end of the input bitstream for decoding.
   * This is mainly needed because some optimized bitstream readers read
   * 32 or 64 bit at once and could read over the end.<br>
   * Note: If the first 23 bits of the additional bytes are not 0, then damaged
   * MPEG bitstreams could cause overread and segfault.
   */
  #define FF_INPUT_BUFFER_PADDING_SIZE 32
  
  /**
   * @ingroup lavc_encoding
   * minimum encoding buffer size
   * Used to avoid some checks during header writing.
   */
  #define FF_MIN_BUFFER_SIZE 16384
  
  
  /**
   * @ingroup lavc_encoding
   * motion estimation type.
   */
  enum Motion_Est_ID {
      ME_ZERO = 1,    ///< no search, that is use 0,0 vector whenever one is needed
      ME_FULL,
      ME_LOG,
      ME_PHODS,
      ME_EPZS,        ///< enhanced predictive zonal search
      ME_X1,          ///< reserved for experiments
      ME_HEX,         ///< hexagon based search
      ME_UMH,         ///< uneven multi-hexagon search
      ME_TESA,        ///< transformed exhaustive search algorithm
      ME_ITER=50,     ///< iterative search
  };
  
  /**
   * @ingroup lavc_decoding
   */
  enum AVDiscard{
      /* We leave some space between them for extensions (drop some
       * keyframes for intra-only or drop just some bidir frames). */
      AVDISCARD_NONE    =-16, ///< discard nothing
      AVDISCARD_DEFAULT =  0, ///< discard useless packets like 0 size packets in avi
      AVDISCARD_NONREF  =  8, ///< discard all non reference
      AVDISCARD_BIDIR   = 16, ///< discard all bidirectional frames
      AVDISCARD_NONINTRA= 24, ///< discard all non intra frames
      AVDISCARD_NONKEY  = 32, ///< discard all frames except keyframes
      AVDISCARD_ALL     = 48, ///< discard all
  };
  
  enum AVAudioServiceType {
      AV_AUDIO_SERVICE_TYPE_MAIN              = 0,
      AV_AUDIO_SERVICE_TYPE_EFFECTS           = 1,
      AV_AUDIO_SERVICE_TYPE_VISUALLY_IMPAIRED = 2,
      AV_AUDIO_SERVICE_TYPE_HEARING_IMPAIRED  = 3,
      AV_AUDIO_SERVICE_TYPE_DIALOGUE          = 4,
      AV_AUDIO_SERVICE_TYPE_COMMENTARY        = 5,
      AV_AUDIO_SERVICE_TYPE_EMERGENCY         = 6,
      AV_AUDIO_SERVICE_TYPE_VOICE_OVER        = 7,
      AV_AUDIO_SERVICE_TYPE_KARAOKE           = 8,
      AV_AUDIO_SERVICE_TYPE_NB                   , ///< Not part of ABI
  };
  
  /**
   * @ingroup lavc_encoding
   */
  typedef struct RcOverride{
      int start_frame;
      int end_frame;
      int qscale; // If this is 0 then quality_factor will be used instead.
      float quality_factor;
  } RcOverride;
  
  #if FF_API_MAX_BFRAMES
  /**
   * @deprecated there is no libavcodec-wide limit on the number of B-frames
   */
  #define FF_MAX_B_FRAMES 16
  #endif
  
  /* encoding support
     These flags can be passed in AVCodecContext.flags before initialization.
     Note: Not everything is supported yet.
  */
  
  /**
   * Allow decoders to produce frames with data planes that are not aligned
   * to CPU requirements (e.g. due to cropping).
   */
  #define CODEC_FLAG_UNALIGNED 0x0001
  #define CODEC_FLAG_QSCALE 0x0002  ///< Use fixed qscale.
  #define CODEC_FLAG_4MV    0x0004  ///< 4 MV per MB allowed / advanced prediction for H.263.
  #define CODEC_FLAG_OUTPUT_CORRUPT 0x0008 ///< Output even those frames that might be corrupted
  #define CODEC_FLAG_QPEL   0x0010  ///< Use qpel MC.
  #if FF_API_GMC
  /**
   * @deprecated use the "gmc" private option of the libxvid encoder
   */
  #define CODEC_FLAG_GMC    0x0020  ///< Use GMC.
  #endif
  #if FF_API_MV0
  /**
   * @deprecated use the flag "mv0" in the "mpv_flags" private option of the
   * mpegvideo encoders
   */
  #define CODEC_FLAG_MV0    0x0040
  #endif
  #if FF_API_INPUT_PRESERVED
  /**
   * @deprecated passing reference-counted frames to the encoders replaces this
   * flag
   */
  #define CODEC_FLAG_INPUT_PRESERVED 0x0100
  #endif
  #define CODEC_FLAG_PASS1           0x0200   ///< Use internal 2pass ratecontrol in first pass mode.
  #define CODEC_FLAG_PASS2           0x0400   ///< Use internal 2pass ratecontrol in second pass mode.
  #define CODEC_FLAG_GRAY            0x2000   ///< Only decode/encode grayscale.
  #if FF_API_EMU_EDGE
  /**
   * @deprecated edges are not used/required anymore. I.e. this flag is now always
   * set.
   */
  #define CODEC_FLAG_EMU_EDGE        0x4000
  #endif
  #define CODEC_FLAG_PSNR            0x8000   ///< error[?] variables will be set during encoding.
  #define CODEC_FLAG_TRUNCATED       0x00010000 /** Input bitstream might be truncated at a random
                                                    location instead of only at frame boundaries. */
  #if FF_API_NORMALIZE_AQP
  /**
   * @deprecated use the flag "naq" in the "mpv_flags" private option of the
   * mpegvideo encoders
   */
  #define CODEC_FLAG_NORMALIZE_AQP  0x00020000
  #endif
  #define CODEC_FLAG_INTERLACED_DCT 0x00040000 ///< Use interlaced DCT.
  #define CODEC_FLAG_LOW_DELAY      0x00080000 ///< Force low delay.
  #define CODEC_FLAG_GLOBAL_HEADER  0x00400000 ///< Place global headers in extradata instead of every keyframe.
  #define CODEC_FLAG_BITEXACT       0x00800000 ///< Use only bitexact stuff (except (I)DCT).
  /* Fx : Flag for h263+ extra options */
  #define CODEC_FLAG_AC_PRED        0x01000000 ///< H.263 advanced intra coding / MPEG-4 AC prediction
  #define CODEC_FLAG_LOOP_FILTER    0x00000800 ///< loop filter
  #define CODEC_FLAG_INTERLACED_ME  0x20000000 ///< interlaced motion estimation
  #define CODEC_FLAG_CLOSED_GOP     0x80000000
  #define CODEC_FLAG2_FAST          0x00000001 ///< Allow non spec compliant speedup tricks.
  #define CODEC_FLAG2_NO_OUTPUT     0x00000004 ///< Skip bitstream encoding.
  #define CODEC_FLAG2_LOCAL_HEADER  0x00000008 ///< Place global headers at every keyframe instead of in extradata.
  #define CODEC_FLAG2_DROP_FRAME_TIMECODE 0x00002000 ///< timecode is in drop frame format. DEPRECATED!!!!
  #define CODEC_FLAG2_IGNORE_CROP   0x00010000 ///< Discard cropping information from SPS.
  
  #define CODEC_FLAG2_CHUNKS        0x00008000 ///< Input bitstream might be truncated at a packet boundaries instead of only at frame boundaries.
  #define CODEC_FLAG2_SHOW_ALL      0x00400000 ///< Show all frames before the first keyframe
  #define CODEC_FLAG2_EXPORT_MVS    0x10000000 ///< Export motion vectors through frame side data
  #define CODEC_FLAG2_SKIP_MANUAL   0x20000000 ///< Do not skip samples and export skip information as frame side data
  
  /* Unsupported options :
   *              Syntax Arithmetic coding (SAC)
   *              Reference Picture Selection
   *              Independent Segment Decoding */
  /* /Fx */
  /* codec capabilities */
  
  #define CODEC_CAP_DRAW_HORIZ_BAND 0x0001 ///< Decoder can use draw_horiz_band callback.
  /**
   * Codec uses get_buffer() for allocating buffers and supports custom allocators.
   * If not set, it might not use get_buffer() at all or use operations that
   * assume the buffer was allocated by avcodec_default_get_buffer.
   */
  #define CODEC_CAP_DR1             0x0002
  #define CODEC_CAP_TRUNCATED       0x0008
  #if FF_API_XVMC
  /* Codec can export data for HW decoding. This flag indicates that
   * the codec would call get_format() with list that might contain HW accelerated
   * pixel formats (XvMC, VDPAU, VAAPI, etc). The application can pick any of them
   * including raw image format.
   * The application can use the passed context to determine bitstream version,
   * chroma format, resolution etc.
   */
  #define CODEC_CAP_HWACCEL         0x0010
  #endif /* FF_API_XVMC */
  /**
   * Encoder or decoder requires flushing with NULL input at the end in order to
   * give the complete and correct output.
   *
   * NOTE: If this flag is not set, the codec is guaranteed to never be fed with
   *       with NULL data. The user can still send NULL data to the public encode
   *       or decode function, but libavcodec will not pass it along to the codec
   *       unless this flag is set.
   *
   * Decoders:
   * The decoder has a non-zero delay and needs to be fed with avpkt->data=NULL,
   * avpkt->size=0 at the end to get the delayed data until the decoder no longer
   * returns frames.
   *
   * Encoders:
   * The encoder needs to be fed with NULL data at the end of encoding until the
   * encoder no longer returns data.
   *
   * NOTE: For encoders implementing the AVCodec.encode2() function, setting this
   *       flag also means that the encoder must set the pts and duration for
   *       each output packet. If this flag is not set, the pts and duration will
   *       be determined by libavcodec from the input frame.
   */
  #define CODEC_CAP_DELAY           0x0020
  /**
   * Codec can be fed a final frame with a smaller size.
   * This can be used to prevent truncation of the last audio samples.
   */
  #define CODEC_CAP_SMALL_LAST_FRAME 0x0040
  #if FF_API_CAP_VDPAU
  /**
   * Codec can export data for HW decoding (VDPAU).
   */
  #define CODEC_CAP_HWACCEL_VDPAU    0x0080
  #endif
  /**
   * Codec can output multiple frames per AVPacket
   * Normally demuxers return one frame at a time, demuxers which do not do
   * are connected to a parser to split what they return into proper frames.
   * This flag is reserved to the very rare category of codecs which have a
   * bitstream that cannot be split into frames without timeconsuming
   * operations like full decoding. Demuxers carring such bitstreams thus
   * may return multiple frames in a packet. This has many disadvantages like
   * prohibiting stream copy in many cases thus it should only be considered
   * as a last resort.
   */
  #define CODEC_CAP_SUBFRAMES        0x0100
  /**
   * Codec is experimental and is thus avoided in favor of non experimental
   * encoders
   */
  #define CODEC_CAP_EXPERIMENTAL     0x0200
  /**
   * Codec should fill in channel configuration and samplerate instead of container
   */
  #define CODEC_CAP_CHANNEL_CONF     0x0400
  #if FF_API_NEG_LINESIZES
  /**
   * @deprecated no codecs use this capability
   */
  #define CODEC_CAP_NEG_LINESIZES    0x0800
  #endif
  /**
   * Codec supports frame-level multithreading.
   */
  #define CODEC_CAP_FRAME_THREADS    0x1000
  /**
   * Codec supports slice-based (or partition-based) multithreading.
   */
  #define CODEC_CAP_SLICE_THREADS    0x2000
  /**
   * Codec supports changed parameters at any point.
   */
  #define CODEC_CAP_PARAM_CHANGE     0x4000
  /**
   * Codec supports avctx->thread_count == 0 (auto).
   */
  #define CODEC_CAP_AUTO_THREADS     0x8000
  /**
   * Audio encoder supports receiving a different number of samples in each call.
   */
  #define CODEC_CAP_VARIABLE_FRAME_SIZE 0x10000
  /**
   * Codec is intra only.
   */
  #define CODEC_CAP_INTRA_ONLY       0x40000000
  /**
   * Codec is lossless.
   */
  #define CODEC_CAP_LOSSLESS         0x80000000
  
  #if FF_API_MB_TYPE
  //The following defines may change, don't expect compatibility if you use them.
  #define MB_TYPE_INTRA4x4   0x0001
  #define MB_TYPE_INTRA16x16 0x0002 //FIXME H.264-specific
  #define MB_TYPE_INTRA_PCM  0x0004 //FIXME H.264-specific
  #define MB_TYPE_16x16      0x0008
  #define MB_TYPE_16x8       0x0010
  #define MB_TYPE_8x16       0x0020
  #define MB_TYPE_8x8        0x0040
  #define MB_TYPE_INTERLACED 0x0080
  #define MB_TYPE_DIRECT2    0x0100 //FIXME
  #define MB_TYPE_ACPRED     0x0200
  #define MB_TYPE_GMC        0x0400
  #define MB_TYPE_SKIP       0x0800
  #define MB_TYPE_P0L0       0x1000
  #define MB_TYPE_P1L0       0x2000
  #define MB_TYPE_P0L1       0x4000
  #define MB_TYPE_P1L1       0x8000
  #define MB_TYPE_L0         (MB_TYPE_P0L0 | MB_TYPE_P1L0)
  #define MB_TYPE_L1         (MB_TYPE_P0L1 | MB_TYPE_P1L1)
  #define MB_TYPE_L0L1       (MB_TYPE_L0   | MB_TYPE_L1)
  #define MB_TYPE_QUANT      0x00010000
  #define MB_TYPE_CBP        0x00020000
  //Note bits 24-31 are reserved for codec specific use (h264 ref0, mpeg1 0mv, ...)
  #endif
  
  /**
   * Pan Scan area.
   * This specifies the area which should be displayed.
   * Note there may be multiple such areas for one frame.
   */
  typedef struct AVPanScan{
      /**
       * id
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      int id;
  
      /**
       * width and height in 1/16 pel
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      int width;
      int height;
  
      /**
       * position of the top left corner in 1/16 pel for up to 3 fields/frames
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      int16_t position[3][2];
  }AVPanScan;
  
  #if FF_API_QSCALE_TYPE
  #define FF_QSCALE_TYPE_MPEG1 0
  #define FF_QSCALE_TYPE_MPEG2 1
  #define FF_QSCALE_TYPE_H264  2
  #define FF_QSCALE_TYPE_VP56  3
  #endif
  
  #if FF_API_GET_BUFFER
  #define FF_BUFFER_TYPE_INTERNAL 1
  #define FF_BUFFER_TYPE_USER     2 ///< direct rendering buffers (image is (de)allocated by user)
  #define FF_BUFFER_TYPE_SHARED   4 ///< Buffer from somewhere else; don't deallocate image (data/base), all other tables are not shared.
  #define FF_BUFFER_TYPE_COPY     8 ///< Just a (modified) copy of some other buffer, don't deallocate anything.
  
  #define FF_BUFFER_HINTS_VALID    0x01 // Buffer hints value is meaningful (if 0 ignore).
  #define FF_BUFFER_HINTS_READABLE 0x02 // Codec will read from buffer.
  #define FF_BUFFER_HINTS_PRESERVE 0x04 // User must not alter buffer content.
  #define FF_BUFFER_HINTS_REUSABLE 0x08 // Codec will reuse the buffer (update).
  #endif
  
  /**
   * The decoder will keep a reference to the frame and may reuse it later.
   */
  #define AV_GET_BUFFER_FLAG_REF (1 << 0)
  
  /**
   * @defgroup lavc_packet AVPacket
   *
   * Types and functions for working with AVPacket.
   * @{
   */
  enum AVPacketSideDataType {
      AV_PKT_DATA_PALETTE,
      AV_PKT_DATA_NEW_EXTRADATA,
  
      /**
       * An AV_PKT_DATA_PARAM_CHANGE side data packet is laid out as follows:
       * @code
       * u32le param_flags
       * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT)
       *     s32le channel_count
       * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT)
       *     u64le channel_layout
       * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
       *     s32le sample_rate
       * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
       *     s32le width
       *     s32le height
       * @endcode
       */
      AV_PKT_DATA_PARAM_CHANGE,
  
      /**
       * An AV_PKT_DATA_H263_MB_INFO side data packet contains a number of
       * structures with info about macroblocks relevant to splitting the
       * packet into smaller packets on macroblock edges (e.g. as for RFC 2190).
       * That is, it does not necessarily contain info about all macroblocks,
       * as long as the distance between macroblocks in the info is smaller
       * than the target payload size.
       * Each MB info structure is 12 bytes, and is laid out as follows:
       * @code
       * u32le bit offset from the start of the packet
       * u8    current quantizer at the start of the macroblock
       * u8    GOB number
       * u16le macroblock address within the GOB
       * u8    horizontal MV predictor
       * u8    vertical MV predictor
       * u8    horizontal MV predictor for block number 3
       * u8    vertical MV predictor for block number 3
       * @endcode
       */
      AV_PKT_DATA_H263_MB_INFO,
  
      /**
       * This side data should be associated with an audio stream and contains
       * ReplayGain information in form of the AVReplayGain struct.
       */
      AV_PKT_DATA_REPLAYGAIN,
  
      /**
       * This side data contains a 3x3 transformation matrix describing an affine
       * transformation that needs to be applied to the decoded video frames for
       * correct presentation.
       *
       * See libavutil/display.h for a detailed description of the data.
       */
      AV_PKT_DATA_DISPLAYMATRIX,
  
      /**
       * This side data should be associated with a video stream and contains
       * Stereoscopic 3D information in form of the AVStereo3D struct.
       */
      AV_PKT_DATA_STEREO3D,
  
      /**
       * Recommmends skipping the specified number of samples
       * @code
       * u32le number of samples to skip from start of this packet
       * u32le number of samples to skip from end of this packet
       * u8    reason for start skip
       * u8    reason for end   skip (0=padding silence, 1=convergence)
       * @endcode
       */
      AV_PKT_DATA_SKIP_SAMPLES=70,
  
      /**
       * An AV_PKT_DATA_JP_DUALMONO side data packet indicates that
       * the packet may contain "dual mono" audio specific to Japanese DTV
       * and if it is true, recommends only the selected channel to be used.
       * @code
       * u8    selected channels (0=mail/left, 1=sub/right, 2=both)
       * @endcode
       */
      AV_PKT_DATA_JP_DUALMONO,
  
      /**
       * A list of zero terminated key/value strings. There is no end marker for
       * the list, so it is required to rely on the side data size to stop.
       */
      AV_PKT_DATA_STRINGS_METADATA,
  
      /**
       * Subtitle event position
       * @code
       * u32le x1
       * u32le y1
       * u32le x2
       * u32le y2
       * @endcode
       */
      AV_PKT_DATA_SUBTITLE_POSITION,
  
      /**
       * Data found in BlockAdditional element of matroska container. There is
       * no end marker for the data, so it is required to rely on the side data
       * size to recognize the end. 8 byte id (as found in BlockAddId) followed
       * by data.
       */
      AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,
  
      /**
       * The optional first identifier line of a WebVTT cue.
       */
      AV_PKT_DATA_WEBVTT_IDENTIFIER,
  
      /**
       * The optional settings (rendering instructions) that immediately
       * follow the timestamp specifier of a WebVTT cue.
       */
      AV_PKT_DATA_WEBVTT_SETTINGS,
  
      /**
       * A list of zero terminated key/value strings. There is no end marker for
       * the list, so it is required to rely on the side data size to stop. This
       * side data includes updated metadata which appeared in the stream.
       */
      AV_PKT_DATA_METADATA_UPDATE,
  };
  
  typedef struct AVPacketSideData {
      uint8_t *data;
      int      size;
      enum AVPacketSideDataType type;
  } AVPacketSideData;
  
  /**
   * This structure stores compressed data. It is typically exported by demuxers
   * and then passed as input to decoders, or received as output from encoders and
   * then passed to muxers.
   *
   * For video, it should typically contain one compressed frame. For audio it may
   * contain several compressed frames.
   *
   * AVPacket is one of the few structs in FFmpeg, whose size is a part of public
   * ABI. Thus it may be allocated on stack and no new fields can be added to it
   * without libavcodec and libavformat major bump.
   *
   * The semantics of data ownership depends on the buf or destruct (deprecated)
   * fields. If either is set, the packet data is dynamically allocated and is
   * valid indefinitely until av_free_packet() is called (which in turn calls
   * av_buffer_unref()/the destruct callback to free the data). If neither is set,
   * the packet data is typically backed by some static buffer somewhere and is
   * only valid for a limited time (e.g. until the next read call when demuxing).
   *
   * The side data is always allocated with av_malloc() and is freed in
   * av_free_packet().
   */
  typedef struct AVPacket {
      /**
       * A reference to the reference-counted buffer where the packet data is
       * stored.
       * May be NULL, then the packet data is not reference-counted.
       */
      AVBufferRef *buf;
      /**
       * Presentation timestamp in AVStream->time_base units; the time at which
       * the decompressed packet will be presented to the user.
       * Can be AV_NOPTS_VALUE if it is not stored in the file.
       * pts MUST be larger or equal to dts as presentation cannot happen before
       * decompression, unless one wants to view hex dumps. Some formats misuse
       * the terms dts and pts/cts to mean something different. Such timestamps
       * must be converted to true pts/dts before they are stored in AVPacket.
       */
      int64_t pts;
      /**
       * Decompression timestamp in AVStream->time_base units; the time at which
       * the packet is decompressed.
       * Can be AV_NOPTS_VALUE if it is not stored in the file.
       */
      int64_t dts;
      uint8_t *data;
      int   size;
      int   stream_index;
      /**
       * A combination of AV_PKT_FLAG values
       */
      int   flags;
      /**
       * Additional packet data that can be provided by the container.
       * Packet can contain several types of side information.
       */
      AVPacketSideData *side_data;
      int side_data_elems;
  
      /**
       * Duration of this packet in AVStream->time_base units, 0 if unknown.
       * Equals next_pts - this_pts in presentation order.
       */
      int   duration;
  #if FF_API_DESTRUCT_PACKET
      attribute_deprecated
      void  (*destruct)(struct AVPacket *);
      attribute_deprecated
      void  *priv;
  #endif
      int64_t pos;                            ///< byte position in stream, -1 if unknown
  
      /**
       * Time difference in AVStream->time_base units from the pts of this
       * packet to the point at which the output from the decoder has converged
       * independent from the availability of previous frames. That is, the
       * frames are virtually identical no matter if decoding started from
       * the very first frame or from this keyframe.
       * Is AV_NOPTS_VALUE if unknown.
       * This field is not the display duration of the current packet.
       * This field has no meaning if the packet does not have AV_PKT_FLAG_KEY
       * set.
       *
       * The purpose of this field is to allow seeking in streams that have no
       * keyframes in the conventional sense. It corresponds to the
       * recovery point SEI in H.264 and match_time_delta in NUT. It is also
       * essential for some types of subtitle streams to ensure that all
       * subtitles are correctly displayed after seeking.
       */
      int64_t convergence_duration;
  } AVPacket;
  #define AV_PKT_FLAG_KEY     0x0001 ///< The packet contains a keyframe
  #define AV_PKT_FLAG_CORRUPT 0x0002 ///< The packet content is corrupted
  
  enum AVSideDataParamChangeFlags {
      AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT  = 0x0001,
      AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT = 0x0002,
      AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE    = 0x0004,
      AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS     = 0x0008,
  };
  /**
   * @}
   */
  
  struct AVCodecInternal;
  
  enum AVFieldOrder {
      AV_FIELD_UNKNOWN,
      AV_FIELD_PROGRESSIVE,
      AV_FIELD_TT,          //< Top coded_first, top displayed first
      AV_FIELD_BB,          //< Bottom coded first, bottom displayed first
      AV_FIELD_TB,          //< Top coded first, bottom displayed first
      AV_FIELD_BT,          //< Bottom coded first, top displayed first
  };
  
  /**
   * main external API structure.
   * New fields can be added to the end with minor version bumps.
   * Removal, reordering and changes to existing fields require a major
   * version bump.
   * Please use AVOptions (av_opt* / av_set/get*()) to access these fields from user
   * applications.
   * sizeof(AVCodecContext) must not be used outside libav*.
   */
  typedef struct AVCodecContext {
      /**
       * information on struct for av_log
       * - set by avcodec_alloc_context3
       */
      const AVClass *av_class;
      int log_level_offset;
  
      enum AVMediaType codec_type; /* see AVMEDIA_TYPE_xxx */
      const struct AVCodec  *codec;
  #if FF_API_CODEC_NAME
      /**
       * @deprecated this field is not used for anything in libavcodec
       */
      attribute_deprecated
      char             codec_name[32];
  #endif
      enum AVCodecID     codec_id; /* see AV_CODEC_ID_xxx */
  
      /**
       * fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
       * This is used to work around some encoder bugs.
       * A demuxer should set this to what is stored in the field used to identify the codec.
       * If there are multiple such fields in a container then the demuxer should choose the one
       * which maximizes the information about the used codec.
       * If the codec tag field in a container is larger than 32 bits then the demuxer should
       * remap the longer ID to 32 bits with a table or other structure. Alternatively a new
       * extra_codec_tag + size could be added but for this a clear advantage must be demonstrated
       * first.
       * - encoding: Set by user, if not then the default based on codec_id will be used.
       * - decoding: Set by user, will be converted to uppercase by libavcodec during init.
       */
      unsigned int codec_tag;
  
      /**
       * fourcc from the AVI stream header (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
       * This is used to work around some encoder bugs.
       * - encoding: unused
       * - decoding: Set by user, will be converted to uppercase by libavcodec during init.
       */
      unsigned int stream_codec_tag;
  
      void *priv_data;
  
      /**
       * Private context used for internal data.
       *
       * Unlike priv_data, this is not codec-specific. It is used in general
       * libavcodec functions.
       */
      struct AVCodecInternal *internal;
  
      /**
       * Private data of the user, can be used to carry app specific stuff.
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      void *opaque;
  
      /**
       * the average bitrate
       * - encoding: Set by user; unused for constant quantizer encoding.
       * - decoding: Set by libavcodec. 0 or some bitrate if this info is available in the stream.
       */
      int bit_rate;
  
      /**
       * number of bits the bitstream is allowed to diverge from the reference.
       *           the reference can be CBR (for CBR pass1) or VBR (for pass2)
       * - encoding: Set by user; unused for constant quantizer encoding.
       * - decoding: unused
       */
      int bit_rate_tolerance;
  
      /**
       * Global quality for codecs which cannot change it per frame.
       * This should be proportional to MPEG-1/2/4 qscale.
       * - encoding: Set by user.
       * - decoding: unused
       */
      int global_quality;
  
      /**
       * - encoding: Set by user.
       * - decoding: unused
       */
      int compression_level;
  #define FF_COMPRESSION_DEFAULT -1
  
      /**
       * CODEC_FLAG_*.
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int flags;
  
      /**
       * CODEC_FLAG2_*
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int flags2;
  
      /**
       * some codecs need / can use extradata like Huffman tables.
       * mjpeg: Huffman tables
       * rv10: additional flags
       * mpeg4: global headers (they can be in the bitstream or here)
       * The allocated memory should be FF_INPUT_BUFFER_PADDING_SIZE bytes larger
       * than extradata_size to avoid problems if it is read with the bitstream reader.
       * The bytewise contents of extradata must not depend on the architecture or CPU endianness.
       * - encoding: Set/allocated/freed by libavcodec.
       * - decoding: Set/allocated/freed by user.
       */
      uint8_t *extradata;
      int extradata_size;
  
      /**
       * This is the fundamental unit of time (in seconds) in terms
       * of which frame timestamps are represented. For fixed-fps content,
       * timebase should be 1/framerate and timestamp increments should be
       * identically 1.
       * This often, but not always is the inverse of the frame rate or field rate
       * for video.
       * - encoding: MUST be set by user.
       * - decoding: the use of this field for decoding is deprecated.
       *             Use framerate instead.
       */
      AVRational time_base;
  
      /**
       * For some codecs, the time base is closer to the field rate than the frame rate.
       * Most notably, H.264 and MPEG-2 specify time_base as half of frame duration
       * if no telecine is used ...
       *
       * Set to time_base ticks per frame. Default 1, e.g., H.264/MPEG-2 set it to 2.
       */
      int ticks_per_frame;
  
      /**
       * Codec delay.
       *
       * Encoding: Number of frames delay there will be from the encoder input to
       *           the decoder output. (we assume the decoder matches the spec)
       * Decoding: Number of frames delay in addition to what a standard decoder
       *           as specified in the spec would produce.
       *
       * Video:
       *   Number of frames the decoded output will be delayed relative to the
       *   encoded input.
       *
       * Audio:
       *   For encoding, this field is unused (see initial_padding).
       *
       *   For decoding, this is the number of samples the decoder needs to
       *   output before the decoder's output is valid. When seeking, you should
       *   start decoding this many samples prior to your desired seek point.
       *
       * - encoding: Set by libavcodec.
       * - decoding: Set by libavcodec.
       */
      int delay;
  
  
      /* video only */
      /**
       * picture width / height.
       * - encoding: MUST be set by user.
       * - decoding: May be set by the user before opening the decoder if known e.g.
       *             from the container. Some decoders will require the dimensions
       *             to be set by the caller. During decoding, the decoder may
       *             overwrite those values as required.
       */
      int width, height;
  
      /**
       * Bitstream width / height, may be different from width/height e.g. when
       * the decoded frame is cropped before being output or lowres is enabled.
       * - encoding: unused
       * - decoding: May be set by the user before opening the decoder if known
       *             e.g. from the container. During decoding, the decoder may
       *             overwrite those values as required.
       */
      int coded_width, coded_height;
  
  #if FF_API_ASPECT_EXTENDED
  #define FF_ASPECT_EXTENDED 15
  #endif
  
      /**
       * the number of pictures in a group of pictures, or 0 for intra_only
       * - encoding: Set by user.
       * - decoding: unused
       */
      int gop_size;
  
      /**
       * Pixel format, see AV_PIX_FMT_xxx.
       * May be set by the demuxer if known from headers.
       * May be overridden by the decoder if it knows better.
       * - encoding: Set by user.
       * - decoding: Set by user if known, overridden by libavcodec if known
       */
      enum AVPixelFormat pix_fmt;
  
      /**
       * Motion estimation algorithm used for video coding.
       * 1 (zero), 2 (full), 3 (log), 4 (phods), 5 (epzs), 6 (x1), 7 (hex),
       * 8 (umh), 9 (iter), 10 (tesa) [7, 8, 10 are x264 specific, 9 is snow specific]
       * - encoding: MUST be set by user.
       * - decoding: unused
       */
      int me_method;
  
      /**
       * If non NULL, 'draw_horiz_band' is called by the libavcodec
       * decoder to draw a horizontal band. It improves cache usage. Not
       * all codecs can do that. You must check the codec capabilities
       * beforehand.
       * When multithreading is used, it may be called from multiple threads
       * at the same time; threads might draw different parts of the same AVFrame,
       * or multiple AVFrames, and there is no guarantee that slices will be drawn
       * in order.
       * The function is also used by hardware acceleration APIs.
       * It is called at least once during frame decoding to pass
       * the data needed for hardware render.
       * In that mode instead of pixel data, AVFrame points to
       * a structure specific to the acceleration API. The application
       * reads the structure and can change some fields to indicate progress
       * or mark state.
       * - encoding: unused
       * - decoding: Set by user.
       * @param height the height of the slice
       * @param y the y position of the slice
       * @param type 1->top field, 2->bottom field, 3->frame
       * @param offset offset into the AVFrame.data from which the slice should be read
       */
      void (*draw_horiz_band)(struct AVCodecContext *s,
                              const AVFrame *src, int offset[AV_NUM_DATA_POINTERS],
                              int y, int type, int height);
  
      /**
       * callback to negotiate the pixelFormat
       * @param fmt is the list of formats which are supported by the codec,
       * it is terminated by -1 as 0 is a valid format, the formats are ordered by quality.
       * The first is always the native one.
       * @note The callback may be called again immediately if initialization for
       * the selected (hardware-accelerated) pixel format failed.
       * @warning Behavior is undefined if the callback returns a value not
       * in the fmt list of formats.
       * @return the chosen format
       * - encoding: unused
       * - decoding: Set by user, if not set the native format will be chosen.
       */
      enum AVPixelFormat (*get_format)(struct AVCodecContext *s, const enum AVPixelFormat * fmt);
  
      /**
       * maximum number of B-frames between non-B-frames
       * Note: The output will be delayed by max_b_frames+1 relative to the input.
       * - encoding: Set by user.
       * - decoding: unused
       */
      int max_b_frames;
  
      /**
       * qscale factor between IP and B-frames
       * If > 0 then the last P-frame quantizer will be used (q= lastp_q*factor+offset).
       * If < 0 then normal ratecontrol will be done (q= -normal_q*factor+offset).
       * - encoding: Set by user.
       * - decoding: unused
       */
      float b_quant_factor;
  
      /** obsolete FIXME remove */
      int rc_strategy;
  #define FF_RC_STRATEGY_XVID 1
  
      int b_frame_strategy;
  
      /**
       * qscale offset between IP and B-frames
       * - encoding: Set by user.
       * - decoding: unused
       */
      float b_quant_offset;
  
      /**
       * Size of the frame reordering buffer in the decoder.
       * For MPEG-2 it is 1 IPB or 0 low delay IP.
       * - encoding: Set by libavcodec.
       * - decoding: Set by libavcodec.
       */
      int has_b_frames;
  
      /**
       * 0-> h263 quant 1-> mpeg quant
       * - encoding: Set by user.
       * - decoding: unused
       */
      int mpeg_quant;
  
      /**
       * qscale factor between P and I-frames
       * If > 0 then the last p frame quantizer will be used (q= lastp_q*factor+offset).
       * If < 0 then normal ratecontrol will be done (q= -normal_q*factor+offset).
       * - encoding: Set by user.
       * - decoding: unused
       */
      float i_quant_factor;
  
      /**
       * qscale offset between P and I-frames
       * - encoding: Set by user.
       * - decoding: unused
       */
      float i_quant_offset;
  
      /**
       * luminance masking (0-> disabled)
       * - encoding: Set by user.
       * - decoding: unused
       */
      float lumi_masking;
  
      /**
       * temporary complexity masking (0-> disabled)
       * - encoding: Set by user.
       * - decoding: unused
       */
      float temporal_cplx_masking;
  
      /**
       * spatial complexity masking (0-> disabled)
       * - encoding: Set by user.
       * - decoding: unused
       */
      float spatial_cplx_masking;
  
      /**
       * p block masking (0-> disabled)
       * - encoding: Set by user.
       * - decoding: unused
       */
      float p_masking;
  
      /**
       * darkness masking (0-> disabled)
       * - encoding: Set by user.
       * - decoding: unused
       */
      float dark_masking;
  
      /**
       * slice count
       * - encoding: Set by libavcodec.
       * - decoding: Set by user (or 0).
       */
      int slice_count;
      /**
       * prediction method (needed for huffyuv)
       * - encoding: Set by user.
       * - decoding: unused
       */
       int prediction_method;
  #define FF_PRED_LEFT   0
  #define FF_PRED_PLANE  1
  #define FF_PRED_MEDIAN 2
  
      /**
       * slice offsets in the frame in bytes
       * - encoding: Set/allocated by libavcodec.
       * - decoding: Set/allocated by user (or NULL).
       */
      int *slice_offset;
  
      /**
       * sample aspect ratio (0 if unknown)
       * That is the width of a pixel divided by the height of the pixel.
       * Numerator and denominator must be relatively prime and smaller than 256 for some video standards.
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      AVRational sample_aspect_ratio;
  
      /**
       * motion estimation comparison function
       * - encoding: Set by user.
       * - decoding: unused
       */
      int me_cmp;
      /**
       * subpixel motion estimation comparison function
       * - encoding: Set by user.
       * - decoding: unused
       */
      int me_sub_cmp;
      /**
       * macroblock comparison function (not supported yet)
       * - encoding: Set by user.
       * - decoding: unused
       */
      int mb_cmp;
      /**
       * interlaced DCT comparison function
       * - encoding: Set by user.
       * - decoding: unused
       */
      int ildct_cmp;
  #define FF_CMP_SAD    0
  #define FF_CMP_SSE    1
  #define FF_CMP_SATD   2
  #define FF_CMP_DCT    3
  #define FF_CMP_PSNR   4
  #define FF_CMP_BIT    5
  #define FF_CMP_RD     6
  #define FF_CMP_ZERO   7
  #define FF_CMP_VSAD   8
  #define FF_CMP_VSSE   9
  #define FF_CMP_NSSE   10
  #define FF_CMP_W53    11
  #define FF_CMP_W97    12
  #define FF_CMP_DCTMAX 13
  #define FF_CMP_DCT264 14
  #define FF_CMP_CHROMA 256
  
      /**
       * ME diamond size & shape
       * - encoding: Set by user.
       * - decoding: unused
       */
      int dia_size;
  
      /**
       * amount of previous MV predictors (2a+1 x 2a+1 square)
       * - encoding: Set by user.
       * - decoding: unused
       */
      int last_predictor_count;
  
      /**
       * prepass for motion estimation
       * - encoding: Set by user.
       * - decoding: unused
       */
      int pre_me;
  
      /**
       * motion estimation prepass comparison function
       * - encoding: Set by user.
       * - decoding: unused
       */
      int me_pre_cmp;
  
      /**
       * ME prepass diamond size & shape
       * - encoding: Set by user.
       * - decoding: unused
       */
      int pre_dia_size;
  
      /**
       * subpel ME quality
       * - encoding: Set by user.
       * - decoding: unused
       */
      int me_subpel_quality;
  
  #if FF_API_AFD
      /**
       * DTG active format information (additional aspect ratio
       * information only used in DVB MPEG-2 transport streams)
       * 0 if not set.
       *
       * - encoding: unused
       * - decoding: Set by decoder.
       * @deprecated Deprecated in favor of AVSideData
       */
      attribute_deprecated int dtg_active_format;
  #define FF_DTG_AFD_SAME         8
  #define FF_DTG_AFD_4_3          9
  #define FF_DTG_AFD_16_9         10
  #define FF_DTG_AFD_14_9         11
  #define FF_DTG_AFD_4_3_SP_14_9  13
  #define FF_DTG_AFD_16_9_SP_14_9 14
  #define FF_DTG_AFD_SP_4_3       15
  #endif /* FF_API_AFD */
  
      /**
       * maximum motion estimation search range in subpel units
       * If 0 then no limit.
       *
       * - encoding: Set by user.
       * - decoding: unused
       */
      int me_range;
  
      /**
       * intra quantizer bias
       * - encoding: Set by user.
       * - decoding: unused
       */
      int intra_quant_bias;
  #define FF_DEFAULT_QUANT_BIAS 999999
  
      /**
       * inter quantizer bias
       * - encoding: Set by user.
       * - decoding: unused
       */
      int inter_quant_bias;
  
      /**
       * slice flags
       * - encoding: unused
       * - decoding: Set by user.
       */
      int slice_flags;
  #define SLICE_FLAG_CODED_ORDER    0x0001 ///< draw_horiz_band() is called in coded order instead of display
  #define SLICE_FLAG_ALLOW_FIELD    0x0002 ///< allow draw_horiz_band() with field slices (MPEG2 field pics)
  #define SLICE_FLAG_ALLOW_PLANE    0x0004 ///< allow draw_horiz_band() with 1 component at a time (SVQ1)
  
  #if FF_API_XVMC
      /**
       * XVideo Motion Acceleration
       * - encoding: forbidden
       * - decoding: set by decoder
       * @deprecated XvMC doesn't need it anymore.
       */
      attribute_deprecated int xvmc_acceleration;
  #endif /* FF_API_XVMC */
  
      /**
       * macroblock decision mode
       * - encoding: Set by user.
       * - decoding: unused
       */
      int mb_decision;
  #define FF_MB_DECISION_SIMPLE 0        ///< uses mb_cmp
  #define FF_MB_DECISION_BITS   1        ///< chooses the one which needs the fewest bits
  #define FF_MB_DECISION_RD     2        ///< rate distortion
  
      /**
       * custom intra quantization matrix
       * - encoding: Set by user, can be NULL.
       * - decoding: Set by libavcodec.
       */
      uint16_t *intra_matrix;
  
      /**
       * custom inter quantization matrix
       * - encoding: Set by user, can be NULL.
       * - decoding: Set by libavcodec.
       */
      uint16_t *inter_matrix;
  
      /**
       * scene change detection threshold
       * 0 is default, larger means fewer detected scene changes.
       * - encoding: Set by user.
       * - decoding: unused
       */
      int scenechange_threshold;
  
      /**
       * noise reduction strength
       * - encoding: Set by user.
       * - decoding: unused
       */
      int noise_reduction;
  
  #if FF_API_MPV_OPT
      /**
       * @deprecated this field is unused
       */
      attribute_deprecated
      int me_threshold;
  
      /**
       * @deprecated this field is unused
       */
      attribute_deprecated
      int mb_threshold;
  #endif
  
      /**
       * precision of the intra DC coefficient - 8
       * - encoding: Set by user.
       * - decoding: unused
       */
      int intra_dc_precision;
  
      /**
       * Number of macroblock rows at the top which are skipped.
       * - encoding: unused
       * - decoding: Set by user.
       */
      int skip_top;
  
      /**
       * Number of macroblock rows at the bottom which are skipped.
       * - encoding: unused
       * - decoding: Set by user.
       */
      int skip_bottom;
  
  #if FF_API_MPV_OPT
      /**
       * @deprecated use encoder private options instead
       */
      attribute_deprecated
      float border_masking;
  #endif
  
      /**
       * minimum MB lagrange multipler
       * - encoding: Set by user.
       * - decoding: unused
       */
      int mb_lmin;
  
      /**
       * maximum MB lagrange multipler
       * - encoding: Set by user.
       * - decoding: unused
       */
      int mb_lmax;
  
      /**
       *
       * - encoding: Set by user.
       * - decoding: unused
       */
      int me_penalty_compensation;
  
      /**
       *
       * - encoding: Set by user.
       * - decoding: unused
       */
      int bidir_refine;
  
      /**
       *
       * - encoding: Set by user.
       * - decoding: unused
       */
      int brd_scale;
  
      /**
       * minimum GOP size
       * - encoding: Set by user.
       * - decoding: unused
       */
      int keyint_min;
  
      /**
       * number of reference frames
       * - encoding: Set by user.
       * - decoding: Set by lavc.
       */
      int refs;
  
      /**
       * chroma qp offset from luma
       * - encoding: Set by user.
       * - decoding: unused
       */
      int chromaoffset;
  
  #if FF_API_UNUSED_MEMBERS
      /**
       * Multiplied by qscale for each frame and added to scene_change_score.
       * - encoding: Set by user.
       * - decoding: unused
       */
      attribute_deprecated int scenechange_factor;
  #endif
  
      /**
       *
       * Note: Value depends upon the compare function used for fullpel ME.
       * - encoding: Set by user.
       * - decoding: unused
       */
      int mv0_threshold;
  
      /**
       * Adjust sensitivity of b_frame_strategy 1.
       * - encoding: Set by user.
       * - decoding: unused
       */
      int b_sensitivity;
  
      /**
       * Chromaticity coordinates of the source primaries.
       * - encoding: Set by user
       * - decoding: Set by libavcodec
       */
      enum AVColorPrimaries color_primaries;
  
      /**
       * Color Transfer Characteristic.
       * - encoding: Set by user
       * - decoding: Set by libavcodec
       */
      enum AVColorTransferCharacteristic color_trc;
  
      /**
       * YUV colorspace type.
       * - encoding: Set by user
       * - decoding: Set by libavcodec
       */
      enum AVColorSpace colorspace;
  
      /**
       * MPEG vs JPEG YUV range.
       * - encoding: Set by user
       * - decoding: Set by libavcodec
       */
      enum AVColorRange color_range;
  
      /**
       * This defines the location of chroma samples.
       * - encoding: Set by user
       * - decoding: Set by libavcodec
       */
      enum AVChromaLocation chroma_sample_location;
  
      /**
       * Number of slices.
       * Indicates number of picture subdivisions. Used for parallelized
       * decoding.
       * - encoding: Set by user
       * - decoding: unused
       */
      int slices;
  
      /** Field order
       * - encoding: set by libavcodec
       * - decoding: Set by user.
       */
      enum AVFieldOrder field_order;
  
      /* audio only */
      int sample_rate; ///< samples per second
      int channels;    ///< number of audio channels
  
      /**
       * audio sample format
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      enum AVSampleFormat sample_fmt;  ///< sample format
  
      /* The following data should not be initialized. */
      /**
       * Number of samples per channel in an audio frame.
       *
       * - encoding: set by libavcodec in avcodec_open2(). Each submitted frame
       *   except the last must contain exactly frame_size samples per channel.
       *   May be 0 when the codec has CODEC_CAP_VARIABLE_FRAME_SIZE set, then the
       *   frame size is not restricted.
       * - decoding: may be set by some decoders to indicate constant frame size
       */
      int frame_size;
  
      /**
       * Frame counter, set by libavcodec.
       *
       * - decoding: total number of frames returned from the decoder so far.
       * - encoding: total number of frames passed to the encoder so far.
       *
       *   @note the counter is not incremented if encoding/decoding resulted in
       *   an error.
       */
      int frame_number;
  
      /**
       * number of bytes per packet if constant and known or 0
       * Used by some WAV based audio codecs.
       */
      int block_align;
  
      /**
       * Audio cutoff bandwidth (0 means "automatic")
       * - encoding: Set by user.
       * - decoding: unused
       */
      int cutoff;
  
  #if FF_API_REQUEST_CHANNELS
      /**
       * Decoder should decode to this many channels if it can (0 for default)
       * - encoding: unused
       * - decoding: Set by user.
       * @deprecated Deprecated in favor of request_channel_layout.
       */
      attribute_deprecated int request_channels;
  #endif
  
      /**
       * Audio channel layout.
       * - encoding: set by user.
       * - decoding: set by user, may be overwritten by libavcodec.
       */
      uint64_t channel_layout;
  
      /**
       * Request decoder to use this channel layout if it can (0 for default)
       * - encoding: unused
       * - decoding: Set by user.
       */
      uint64_t request_channel_layout;
  
      /**
       * Type of service that the audio stream conveys.
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      enum AVAudioServiceType audio_service_type;
  
      /**
       * desired sample format
       * - encoding: Not used.
       * - decoding: Set by user.
       * Decoder will decode to this format if it can.
       */
      enum AVSampleFormat request_sample_fmt;
  
  #if FF_API_GET_BUFFER
      /**
       * Called at the beginning of each frame to get a buffer for it.
       *
       * The function will set AVFrame.data[], AVFrame.linesize[].
       * AVFrame.extended_data[] must also be set, but it should be the same as
       * AVFrame.data[] except for planar audio with more channels than can fit
       * in AVFrame.data[]. In that case, AVFrame.data[] shall still contain as
       * many data pointers as it can hold.
       *
       * if CODEC_CAP_DR1 is not set then get_buffer() must call
       * avcodec_default_get_buffer() instead of providing buffers allocated by
       * some other means.
       *
       * AVFrame.data[] should be 32- or 16-byte-aligned unless the CPU doesn't
       * need it. avcodec_default_get_buffer() aligns the output buffer properly,
       * but if get_buffer() is overridden then alignment considerations should
       * be taken into account.
       *
       * @see avcodec_default_get_buffer()
       *
       * Video:
       *
       * If pic.reference is set then the frame will be read later by libavcodec.
       * avcodec_align_dimensions2() should be used to find the required width and
       * height, as they normally need to be rounded up to the next multiple of 16.
       *
       * If frame multithreading is used and thread_safe_callbacks is set,
       * it may be called from a different thread, but not from more than one at
       * once. Does not need to be reentrant.
       *
       * @see release_buffer(), reget_buffer()
       * @see avcodec_align_dimensions2()
       *
       * Audio:
       *
       * Decoders request a buffer of a particular size by setting
       * AVFrame.nb_samples prior to calling get_buffer(). The decoder may,
       * however, utilize only part of the buffer by setting AVFrame.nb_samples
       * to a smaller value in the output frame.
       *
       * Decoders cannot use the buffer after returning from
       * avcodec_decode_audio4(), so they will not call release_buffer(), as it
       * is assumed to be released immediately upon return. In some rare cases,
       * a decoder may need to call get_buffer() more than once in a single
       * call to avcodec_decode_audio4(). In that case, when get_buffer() is
       * called again after it has already been called once, the previously
       * acquired buffer is assumed to be released at that time and may not be
       * reused by the decoder.
       *
       * As a convenience, av_samples_get_buffer_size() and
       * av_samples_fill_arrays() in libavutil may be used by custom get_buffer()
       * functions to find the required data size and to fill data pointers and
       * linesize. In AVFrame.linesize, only linesize[0] may be set for audio
       * since all planes must be the same size.
       *
       * @see av_samples_get_buffer_size(), av_samples_fill_arrays()
       *
       * - encoding: unused
       * - decoding: Set by libavcodec, user can override.
       *
       * @deprecated use get_buffer2()
       */
      attribute_deprecated
      int (*get_buffer)(struct AVCodecContext *c, AVFrame *pic);
  
      /**
       * Called to release buffers which were allocated with get_buffer.
       * A released buffer can be reused in get_buffer().
       * pic.data[*] must be set to NULL.
       * May be called from a different thread if frame multithreading is used,
       * but not by more than one thread at once, so does not need to be reentrant.
       * - encoding: unused
       * - decoding: Set by libavcodec, user can override.
       *
       * @deprecated custom freeing callbacks should be set from get_buffer2()
       */
      attribute_deprecated
      void (*release_buffer)(struct AVCodecContext *c, AVFrame *pic);
  
      /**
       * Called at the beginning of a frame to get cr buffer for it.
       * Buffer type (size, hints) must be the same. libavcodec won't check it.
       * libavcodec will pass previous buffer in pic, function should return
       * same buffer or new buffer with old frame "painted" into it.
       * If pic.data[0] == NULL must behave like get_buffer().
       * if CODEC_CAP_DR1 is not set then reget_buffer() must call
       * avcodec_default_reget_buffer() instead of providing buffers allocated by
       * some other means.
       * - encoding: unused
       * - decoding: Set by libavcodec, user can override.
       */
      attribute_deprecated
      int (*reget_buffer)(struct AVCodecContext *c, AVFrame *pic);
  #endif
  
      /**
       * This callback is called at the beginning of each frame to get data
       * buffer(s) for it. There may be one contiguous buffer for all the data or
       * there may be a buffer per each data plane or anything in between. What
       * this means is, you may set however many entries in buf[] you feel necessary.
       * Each buffer must be reference-counted using the AVBuffer API (see description
       * of buf[] below).
       *
       * The following fields will be set in the frame before this callback is
       * called:
       * - format
       * - width, height (video only)
       * - sample_rate, channel_layout, nb_samples (audio only)
       * Their values may differ from the corresponding values in
       * AVCodecContext. This callback must use the frame values, not the codec
       * context values, to calculate the required buffer size.
       *
       * This callback must fill the following fields in the frame:
       * - data[]
       * - linesize[]
       * - extended_data:
       *   * if the data is planar audio with more than 8 channels, then this
       *     callback must allocate and fill extended_data to contain all pointers
       *     to all data planes. data[] must hold as many pointers as it can.
       *     extended_data must be allocated with av_malloc() and will be freed in
       *     av_frame_unref().
       *   * otherwise exended_data must point to data
       * - buf[] must contain one or more pointers to AVBufferRef structures. Each of
       *   the frame's data and extended_data pointers must be contained in these. That
       *   is, one AVBufferRef for each allocated chunk of memory, not necessarily one
       *   AVBufferRef per data[] entry. See: av_buffer_create(), av_buffer_alloc(),
       *   and av_buffer_ref().
       * - extended_buf and nb_extended_buf must be allocated with av_malloc() by
       *   this callback and filled with the extra buffers if there are more
       *   buffers than buf[] can hold. extended_buf will be freed in
       *   av_frame_unref().
       *
       * If CODEC_CAP_DR1 is not set then get_buffer2() must call
       * avcodec_default_get_buffer2() instead of providing buffers allocated by
       * some other means.
       *
       * Each data plane must be aligned to the maximum required by the target
       * CPU.
       *
       * @see avcodec_default_get_buffer2()
       *
       * Video:
       *
       * If AV_GET_BUFFER_FLAG_REF is set in flags then the frame may be reused
       * (read and/or written to if it is writable) later by libavcodec.
       *
       * avcodec_align_dimensions2() should be used to find the required width and
       * height, as they normally need to be rounded up to the next multiple of 16.
       *
       * Some decoders do not support linesizes changing between frames.
       *
       * If frame multithreading is used and thread_safe_callbacks is set,
       * this callback may be called from a different thread, but not from more
       * than one at once. Does not need to be reentrant.
       *
       * @see avcodec_align_dimensions2()
       *
       * Audio:
       *
       * Decoders request a buffer of a particular size by setting
       * AVFrame.nb_samples prior to calling get_buffer2(). The decoder may,
       * however, utilize only part of the buffer by setting AVFrame.nb_samples
       * to a smaller value in the output frame.
       *
       * As a convenience, av_samples_get_buffer_size() and
       * av_samples_fill_arrays() in libavutil may be used by custom get_buffer2()
       * functions to find the required data size and to fill data pointers and
       * linesize. In AVFrame.linesize, only linesize[0] may be set for audio
       * since all planes must be the same size.
       *
       * @see av_samples_get_buffer_size(), av_samples_fill_arrays()
       *
       * - encoding: unused
       * - decoding: Set by libavcodec, user can override.
       */
      int (*get_buffer2)(struct AVCodecContext *s, AVFrame *frame, int flags);
  
      /**
       * If non-zero, the decoded audio and video frames returned from
       * avcodec_decode_video2() and avcodec_decode_audio4() are reference-counted
       * and are valid indefinitely. The caller must free them with
       * av_frame_unref() when they are not needed anymore.
       * Otherwise, the decoded frames must not be freed by the caller and are
       * only valid until the next decode call.
       *
       * - encoding: unused
       * - decoding: set by the caller before avcodec_open2().
       */
      int refcounted_frames;
  
      /* - encoding parameters */
      float qcompress;  ///< amount of qscale change between easy & hard scenes (0.0-1.0)
      float qblur;      ///< amount of qscale smoothing over time (0.0-1.0)
  
      /**
       * minimum quantizer
       * - encoding: Set by user.
       * - decoding: unused
       */
      int qmin;
  
      /**
       * maximum quantizer
       * - encoding: Set by user.
       * - decoding: unused
       */
      int qmax;
  
      /**
       * maximum quantizer difference between frames
       * - encoding: Set by user.
       * - decoding: unused
       */
      int max_qdiff;
  
  #if FF_API_MPV_OPT
      /**
       * @deprecated use encoder private options instead
       */
      attribute_deprecated
      float rc_qsquish;
  
      attribute_deprecated
      float rc_qmod_amp;
      attribute_deprecated
      int rc_qmod_freq;
  #endif
  
      /**
       * decoder bitstream buffer size
       * - encoding: Set by user.
       * - decoding: unused
       */
      int rc_buffer_size;
  
      /**
       * ratecontrol override, see RcOverride
       * - encoding: Allocated/set/freed by user.
       * - decoding: unused
       */
      int rc_override_count;
      RcOverride *rc_override;
  
  #if FF_API_MPV_OPT
      /**
       * @deprecated use encoder private options instead
       */
      attribute_deprecated
      const char *rc_eq;
  #endif
  
      /**
       * maximum bitrate
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
      int rc_max_rate;
  
      /**
       * minimum bitrate
       * - encoding: Set by user.
       * - decoding: unused
       */
      int rc_min_rate;
  
  #if FF_API_MPV_OPT
      /**
       * @deprecated use encoder private options instead
       */
      attribute_deprecated
      float rc_buffer_aggressivity;
  
      attribute_deprecated
      float rc_initial_cplx;
  #endif
  
      /**
       * Ratecontrol attempt to use, at maximum, <value> of what can be used without an underflow.
       * - encoding: Set by user.
       * - decoding: unused.
       */
      float rc_max_available_vbv_use;
  
      /**
       * Ratecontrol attempt to use, at least, <value> times the amount needed to prevent a vbv overflow.
       * - encoding: Set by user.
       * - decoding: unused.
       */
      float rc_min_vbv_overflow_use;
  
      /**
       * Number of bits which should be loaded into the rc buffer before decoding starts.
       * - encoding: Set by user.
       * - decoding: unused
       */
      int rc_initial_buffer_occupancy;
  
  #define FF_CODER_TYPE_VLC       0
  #define FF_CODER_TYPE_AC        1
  #define FF_CODER_TYPE_RAW       2
  #define FF_CODER_TYPE_RLE       3
  #if FF_API_UNUSED_MEMBERS
  #define FF_CODER_TYPE_DEFLATE   4
  #endif /* FF_API_UNUSED_MEMBERS */
      /**
       * coder type
       * - encoding: Set by user.
       * - decoding: unused
       */
      int coder_type;
  
      /**
       * context model
       * - encoding: Set by user.
       * - decoding: unused
       */
      int context_model;
  
  #if FF_API_MPV_OPT
      /**
       * @deprecated use encoder private options instead
       */
      attribute_deprecated
      int lmin;
  
      /**
       * @deprecated use encoder private options instead
       */
      attribute_deprecated
      int lmax;
  #endif
  
      /**
       * frame skip threshold
       * - encoding: Set by user.
       * - decoding: unused
       */
      int frame_skip_threshold;
  
      /**
       * frame skip factor
       * - encoding: Set by user.
       * - decoding: unused
       */
      int frame_skip_factor;
  
      /**
       * frame skip exponent
       * - encoding: Set by user.
       * - decoding: unused
       */
      int frame_skip_exp;
  
      /**
       * frame skip comparison function
       * - encoding: Set by user.
       * - decoding: unused
       */
      int frame_skip_cmp;
  
      /**
       * trellis RD quantization
       * - encoding: Set by user.
       * - decoding: unused
       */
      int trellis;
  
      /**
       * - encoding: Set by user.
       * - decoding: unused
       */
      int min_prediction_order;
  
      /**
       * - encoding: Set by user.
       * - decoding: unused
       */
      int max_prediction_order;
  
      /**
       * GOP timecode frame start number
       * - encoding: Set by user, in non drop frame format
       * - decoding: Set by libavcodec (timecode in the 25 bits format, -1 if unset)
       */
      int64_t timecode_frame_start;
  
      /* The RTP callback: This function is called    */
      /* every time the encoder has a packet to send. */
      /* It depends on the encoder if the data starts */
      /* with a Start Code (it should). H.263 does.   */
      /* mb_nb contains the number of macroblocks     */
      /* encoded in the RTP payload.                  */
      void (*rtp_callback)(struct AVCodecContext *avctx, void *data, int size, int mb_nb);
  
      int rtp_payload_size;   /* The size of the RTP payload: the coder will  */
                              /* do its best to deliver a chunk with size     */
                              /* below rtp_payload_size, the chunk will start */
                              /* with a start code on some codecs like H.263. */
                              /* This doesn't take account of any particular  */
                              /* headers inside the transmitted RTP payload.  */
  
      /* statistics, used for 2-pass encoding */
      int mv_bits;
      int header_bits;
      int i_tex_bits;
      int p_tex_bits;
      int i_count;
      int p_count;
      int skip_count;
      int misc_bits;
  
      /**
       * number of bits used for the previously encoded frame
       * - encoding: Set by libavcodec.
       * - decoding: unused
       */
      int frame_bits;
  
      /**
       * pass1 encoding statistics output buffer
       * - encoding: Set by libavcodec.
       * - decoding: unused
       */
      char *stats_out;
  
      /**
       * pass2 encoding statistics input buffer
       * Concatenated stuff from stats_out of pass1 should be placed here.
       * - encoding: Allocated/set/freed by user.
       * - decoding: unused
       */
      char *stats_in;
  
      /**
       * Work around bugs in encoders which sometimes cannot be detected automatically.
       * - encoding: Set by user
       * - decoding: Set by user
       */
      int workaround_bugs;
  #define FF_BUG_AUTODETECT       1  ///< autodetection
  #if FF_API_OLD_MSMPEG4
  #define FF_BUG_OLD_MSMPEG4      2
  #endif
  #define FF_BUG_XVID_ILACE       4
  #define FF_BUG_UMP4             8
  #define FF_BUG_NO_PADDING       16
  #define FF_BUG_AMV              32
  #if FF_API_AC_VLC
  #define FF_BUG_AC_VLC           0  ///< Will be removed, libavcodec can now handle these non-compliant files by default.
  #endif
  #define FF_BUG_QPEL_CHROMA      64
  #define FF_BUG_STD_QPEL         128
  #define FF_BUG_QPEL_CHROMA2     256
  #define FF_BUG_DIRECT_BLOCKSIZE 512
  #define FF_BUG_EDGE             1024
  #define FF_BUG_HPEL_CHROMA      2048
  #define FF_BUG_DC_CLIP          4096
  #define FF_BUG_MS               8192 ///< Work around various bugs in Microsoft's broken decoders.
  #define FF_BUG_TRUNCATED       16384
  
      /**
       * strictly follow the standard (MPEG4, ...).
       * - encoding: Set by user.
       * - decoding: Set by user.
       * Setting this to STRICT or higher means the encoder and decoder will
       * generally do stupid things, whereas setting it to unofficial or lower
       * will mean the encoder might produce output that is not supported by all
       * spec-compliant decoders. Decoders don't differentiate between normal,
       * unofficial and experimental (that is, they always try to decode things
       * when they can) unless they are explicitly asked to behave stupidly
       * (=strictly conform to the specs)
       */
      int strict_std_compliance;
  #define FF_COMPLIANCE_VERY_STRICT   2 ///< Strictly conform to an older more strict version of the spec or reference software.
  #define FF_COMPLIANCE_STRICT        1 ///< Strictly conform to all the things in the spec no matter what consequences.
  #define FF_COMPLIANCE_NORMAL        0
  #define FF_COMPLIANCE_UNOFFICIAL   -1 ///< Allow unofficial extensions
  #define FF_COMPLIANCE_EXPERIMENTAL -2 ///< Allow nonstandardized experimental things.
  
      /**
       * error concealment flags
       * - encoding: unused
       * - decoding: Set by user.
       */
      int error_concealment;
  #define FF_EC_GUESS_MVS   1
  #define FF_EC_DEBLOCK     2
  #define FF_EC_FAVOR_INTER 256
  
      /**
       * debug
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int debug;
  #define FF_DEBUG_PICT_INFO   1
  #define FF_DEBUG_RC          2
  #define FF_DEBUG_BITSTREAM   4
  #define FF_DEBUG_MB_TYPE     8
  #define FF_DEBUG_QP          16
  #if FF_API_DEBUG_MV
  /**
   * @deprecated this option does nothing
   */
  #define FF_DEBUG_MV          32
  #endif
  #define FF_DEBUG_DCT_COEFF   0x00000040
  #define FF_DEBUG_SKIP        0x00000080
  #define FF_DEBUG_STARTCODE   0x00000100
  #if FF_API_UNUSED_MEMBERS
  #define FF_DEBUG_PTS         0x00000200
  #endif /* FF_API_UNUSED_MEMBERS */
  #define FF_DEBUG_ER          0x00000400
  #define FF_DEBUG_MMCO        0x00000800
  #define FF_DEBUG_BUGS        0x00001000
  #if FF_API_DEBUG_MV
  #define FF_DEBUG_VIS_QP      0x00002000 ///< only access through AVOptions from outside libavcodec
  #define FF_DEBUG_VIS_MB_TYPE 0x00004000 ///< only access through AVOptions from outside libavcodec
  #endif
  #define FF_DEBUG_BUFFERS     0x00008000
  #define FF_DEBUG_THREADS     0x00010000
  #define FF_DEBUG_NOMC        0x01000000
  
  #if FF_API_DEBUG_MV
      /**
       * debug
       * Code outside libavcodec should access this field using AVOptions
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int debug_mv;
  #define FF_DEBUG_VIS_MV_P_FOR  0x00000001 //visualize forward predicted MVs of P frames
  #define FF_DEBUG_VIS_MV_B_FOR  0x00000002 //visualize forward predicted MVs of B frames
  #define FF_DEBUG_VIS_MV_B_BACK 0x00000004 //visualize backward predicted MVs of B frames
  #endif
  
      /**
       * Error recognition; may misdetect some more or less valid parts as errors.
       * - encoding: unused
       * - decoding: Set by user.
       */
      int err_recognition;
  
  /**
   * Verify checksums embedded in the bitstream (could be of either encoded or
   * decoded data, depending on the codec) and print an error message on mismatch.
   * If AV_EF_EXPLODE is also set, a mismatching checksum will result in the
   * decoder returning an error.
   */
  #define AV_EF_CRCCHECK  (1<<0)
  #define AV_EF_BITSTREAM (1<<1)          ///< detect bitstream specification deviations
  #define AV_EF_BUFFER    (1<<2)          ///< detect improper bitstream length
  #define AV_EF_EXPLODE   (1<<3)          ///< abort decoding on minor error detection
  
  #define AV_EF_IGNORE_ERR (1<<15)        ///< ignore errors and continue
  #define AV_EF_CAREFUL    (1<<16)        ///< consider things that violate the spec, are fast to calculate and have not been seen in the wild as errors
  #define AV_EF_COMPLIANT  (1<<17)        ///< consider all spec non compliances as errors
  #define AV_EF_AGGRESSIVE (1<<18)        ///< consider things that a sane encoder should not do as an error
  
  
      /**
       * opaque 64bit number (generally a PTS) that will be reordered and
       * output in AVFrame.reordered_opaque
       * - encoding: unused
       * - decoding: Set by user.
       */
      int64_t reordered_opaque;
  
      /**
       * Hardware accelerator in use
       * - encoding: unused.
       * - decoding: Set by libavcodec
       */
      struct AVHWAccel *hwaccel;
  
      /**
       * Hardware accelerator context.
       * For some hardware accelerators, a global context needs to be
       * provided by the user. In that case, this holds display-dependent
       * data FFmpeg cannot instantiate itself. Please refer to the
       * FFmpeg HW accelerator documentation to know how to fill this
       * is. e.g. for VA API, this is a struct vaapi_context.
       * - encoding: unused
       * - decoding: Set by user
       */
      void *hwaccel_context;
  
      /**
       * error
       * - encoding: Set by libavcodec if flags&CODEC_FLAG_PSNR.
       * - decoding: unused
       */
      uint64_t error[AV_NUM_DATA_POINTERS];
  
      /**
       * DCT algorithm, see FF_DCT_* below
       * - encoding: Set by user.
       * - decoding: unused
       */
      int dct_algo;
  #define FF_DCT_AUTO    0
  #define FF_DCT_FASTINT 1
  #if FF_API_UNUSED_MEMBERS
  #define FF_DCT_INT     2
  #endif /* FF_API_UNUSED_MEMBERS */
  #define FF_DCT_MMX     3
  #define FF_DCT_ALTIVEC 5
  #define FF_DCT_FAAN    6
  
      /**
       * IDCT algorithm, see FF_IDCT_* below.
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int idct_algo;
  #define FF_IDCT_AUTO          0
  #define FF_IDCT_INT           1
  #define FF_IDCT_SIMPLE        2
  #define FF_IDCT_SIMPLEMMX     3
  #define FF_IDCT_ARM           7
  #define FF_IDCT_ALTIVEC       8
  #if FF_API_ARCH_SH4
  #define FF_IDCT_SH4           9
  #endif
  #define FF_IDCT_SIMPLEARM     10
  #if FF_API_UNUSED_MEMBERS
  #define FF_IDCT_IPP           13
  #endif /* FF_API_UNUSED_MEMBERS */
  #define FF_IDCT_XVID          14
  #if FF_API_IDCT_XVIDMMX
  #define FF_IDCT_XVIDMMX       14
  #endif /* FF_API_IDCT_XVIDMMX */
  #define FF_IDCT_SIMPLEARMV5TE 16
  #define FF_IDCT_SIMPLEARMV6   17
  #if FF_API_ARCH_SPARC
  #define FF_IDCT_SIMPLEVIS     18
  #endif
  #define FF_IDCT_FAAN          20
  #define FF_IDCT_SIMPLENEON    22
  #if FF_API_ARCH_ALPHA
  #define FF_IDCT_SIMPLEALPHA   23
  #endif
  #define FF_IDCT_SIMPLEAUTO    128
  
      /**
       * bits per sample/pixel from the demuxer (needed for huffyuv).
       * - encoding: Set by libavcodec.
       * - decoding: Set by user.
       */
       int bits_per_coded_sample;
  
      /**
       * Bits per sample/pixel of internal libavcodec pixel/sample format.
       * - encoding: set by user.
       * - decoding: set by libavcodec.
       */
      int bits_per_raw_sample;
  
  #if FF_API_LOWRES
      /**
       * low resolution decoding, 1-> 1/2 size, 2->1/4 size
       * - encoding: unused
       * - decoding: Set by user.
       * Code outside libavcodec should access this field using:
       * av_codec_{get,set}_lowres(avctx)
       */
       int lowres;
  #endif
  
      /**
       * the picture in the bitstream
       * - encoding: Set by libavcodec.
       * - decoding: unused
       */
      AVFrame *coded_frame;
  
      /**
       * thread count
       * is used to decide how many independent tasks should be passed to execute()
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int thread_count;
  
      /**
       * Which multithreading methods to use.
       * Use of FF_THREAD_FRAME will increase decoding delay by one frame per thread,
       * so clients which cannot provide future frames should not use it.
       *
       * - encoding: Set by user, otherwise the default is used.
       * - decoding: Set by user, otherwise the default is used.
       */
      int thread_type;
  #define FF_THREAD_FRAME   1 ///< Decode more than one frame at once
  #define FF_THREAD_SLICE   2 ///< Decode more than one part of a single frame at once
  
      /**
       * Which multithreading methods are in use by the codec.
       * - encoding: Set by libavcodec.
       * - decoding: Set by libavcodec.
       */
      int active_thread_type;
  
      /**
       * Set by the client if its custom get_buffer() callback can be called
       * synchronously from another thread, which allows faster multithreaded decoding.
       * draw_horiz_band() will be called from other threads regardless of this setting.
       * Ignored if the default get_buffer() is used.
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int thread_safe_callbacks;
  
      /**
       * The codec may call this to execute several independent things.
       * It will return only after finishing all tasks.
       * The user may replace this with some multithreaded implementation,
       * the default implementation will execute the parts serially.
       * @param count the number of things to execute
       * - encoding: Set by libavcodec, user can override.
       * - decoding: Set by libavcodec, user can override.
       */
      int (*execute)(struct AVCodecContext *c, int (*func)(struct AVCodecContext *c2, void *arg), void *arg2, int *ret, int count, int size);
  
      /**
       * The codec may call this to execute several independent things.
       * It will return only after finishing all tasks.
       * The user may replace this with some multithreaded implementation,
       * the default implementation will execute the parts serially.
       * Also see avcodec_thread_init and e.g. the --enable-pthread configure option.
       * @param c context passed also to func
       * @param count the number of things to execute
       * @param arg2 argument passed unchanged to func
       * @param ret return values of executed functions, must have space for "count" values. May be NULL.
       * @param func function that will be called count times, with jobnr from 0 to count-1.
       *             threadnr will be in the range 0 to c->thread_count-1 < MAX_THREADS and so that no
       *             two instances of func executing at the same time will have the same threadnr.
       * @return always 0 currently, but code should handle a future improvement where when any call to func
       *         returns < 0 no further calls to func may be done and < 0 is returned.
       * - encoding: Set by libavcodec, user can override.
       * - decoding: Set by libavcodec, user can override.
       */
      int (*execute2)(struct AVCodecContext *c, int (*func)(struct AVCodecContext *c2, void *arg, int jobnr, int threadnr), void *arg2, int *ret, int count);
  
  #if FF_API_THREAD_OPAQUE
      /**
       * @deprecated this field should not be used from outside of lavc
       */
      attribute_deprecated
      void *thread_opaque;
  #endif
  
      /**
       * noise vs. sse weight for the nsse comparison function
       * - encoding: Set by user.
       * - decoding: unused
       */
       int nsse_weight;
  
      /**
       * profile
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
       int profile;
  #define FF_PROFILE_UNKNOWN -99
  #define FF_PROFILE_RESERVED -100
  
  #define FF_PROFILE_AAC_MAIN 0
  #define FF_PROFILE_AAC_LOW  1
  #define FF_PROFILE_AAC_SSR  2
  #define FF_PROFILE_AAC_LTP  3
  #define FF_PROFILE_AAC_HE   4
  #define FF_PROFILE_AAC_HE_V2 28
  #define FF_PROFILE_AAC_LD   22
  #define FF_PROFILE_AAC_ELD  38
  #define FF_PROFILE_MPEG2_AAC_LOW 128
  #define FF_PROFILE_MPEG2_AAC_HE  131
  
  #define FF_PROFILE_DTS         20
  #define FF_PROFILE_DTS_ES      30
  #define FF_PROFILE_DTS_96_24   40
  #define FF_PROFILE_DTS_HD_HRA  50
  #define FF_PROFILE_DTS_HD_MA   60
  
  #define FF_PROFILE_MPEG2_422    0
  #define FF_PROFILE_MPEG2_HIGH   1
  #define FF_PROFILE_MPEG2_SS     2
  #define FF_PROFILE_MPEG2_SNR_SCALABLE  3
  #define FF_PROFILE_MPEG2_MAIN   4
  #define FF_PROFILE_MPEG2_SIMPLE 5
  
  #define FF_PROFILE_H264_CONSTRAINED  (1<<9)  // 8+1; constraint_set1_flag
  #define FF_PROFILE_H264_INTRA        (1<<11) // 8+3; constraint_set3_flag
  
  #define FF_PROFILE_H264_BASELINE             66
  #define FF_PROFILE_H264_CONSTRAINED_BASELINE (66|FF_PROFILE_H264_CONSTRAINED)
  #define FF_PROFILE_H264_MAIN                 77
  #define FF_PROFILE_H264_EXTENDED             88
  #define FF_PROFILE_H264_HIGH                 100
  #define FF_PROFILE_H264_HIGH_10              110
  #define FF_PROFILE_H264_HIGH_10_INTRA        (110|FF_PROFILE_H264_INTRA)
  #define FF_PROFILE_H264_HIGH_422             122
  #define FF_PROFILE_H264_HIGH_422_INTRA       (122|FF_PROFILE_H264_INTRA)
  #define FF_PROFILE_H264_HIGH_444             144
  #define FF_PROFILE_H264_HIGH_444_PREDICTIVE  244
  #define FF_PROFILE_H264_HIGH_444_INTRA       (244|FF_PROFILE_H264_INTRA)
  #define FF_PROFILE_H264_CAVLC_444            44
  
  #define FF_PROFILE_VC1_SIMPLE   0
  #define FF_PROFILE_VC1_MAIN     1
  #define FF_PROFILE_VC1_COMPLEX  2
  #define FF_PROFILE_VC1_ADVANCED 3
  
  #define FF_PROFILE_MPEG4_SIMPLE                     0
  #define FF_PROFILE_MPEG4_SIMPLE_SCALABLE            1
  #define FF_PROFILE_MPEG4_CORE                       2
  #define FF_PROFILE_MPEG4_MAIN                       3
  #define FF_PROFILE_MPEG4_N_BIT                      4
  #define FF_PROFILE_MPEG4_SCALABLE_TEXTURE           5
  #define FF_PROFILE_MPEG4_SIMPLE_FACE_ANIMATION      6
  #define FF_PROFILE_MPEG4_BASIC_ANIMATED_TEXTURE     7
  #define FF_PROFILE_MPEG4_HYBRID                     8
  #define FF_PROFILE_MPEG4_ADVANCED_REAL_TIME         9
  #define FF_PROFILE_MPEG4_CORE_SCALABLE             10
  #define FF_PROFILE_MPEG4_ADVANCED_CODING           11
  #define FF_PROFILE_MPEG4_ADVANCED_CORE             12
  #define FF_PROFILE_MPEG4_ADVANCED_SCALABLE_TEXTURE 13
  #define FF_PROFILE_MPEG4_SIMPLE_STUDIO             14
  #define FF_PROFILE_MPEG4_ADVANCED_SIMPLE           15
  
  #define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_0   0
  #define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_1   1
  #define FF_PROFILE_JPEG2000_CSTREAM_NO_RESTRICTION  2
  #define FF_PROFILE_JPEG2000_DCINEMA_2K              3
  #define FF_PROFILE_JPEG2000_DCINEMA_4K              4
  
  
  #define FF_PROFILE_HEVC_MAIN                        1
  #define FF_PROFILE_HEVC_MAIN_10                     2
  #define FF_PROFILE_HEVC_MAIN_STILL_PICTURE          3
  #define FF_PROFILE_HEVC_REXT                        4
  
      /**
       * level
       * - encoding: Set by user.
       * - decoding: Set by libavcodec.
       */
       int level;
  #define FF_LEVEL_UNKNOWN -99
  
      /**
       * Skip loop filtering for selected frames.
       * - encoding: unused
       * - decoding: Set by user.
       */
      enum AVDiscard skip_loop_filter;
  
      /**
       * Skip IDCT/dequantization for selected frames.
       * - encoding: unused
       * - decoding: Set by user.
       */
      enum AVDiscard skip_idct;
  
      /**
       * Skip decoding for selected frames.
       * - encoding: unused
       * - decoding: Set by user.
       */
      enum AVDiscard skip_frame;
  
      /**
       * Header containing style information for text subtitles.
       * For SUBTITLE_ASS subtitle type, it should contain the whole ASS
       * [Script Info] and [V4+ Styles] section, plus the [Events] line and
       * the Format line following. It shouldn't include any Dialogue line.
       * - encoding: Set/allocated/freed by user (before avcodec_open2())
       * - decoding: Set/allocated/freed by libavcodec (by avcodec_open2())
       */
      uint8_t *subtitle_header;
      int subtitle_header_size;
  
  #if FF_API_ERROR_RATE
      /**
       * @deprecated use the 'error_rate' private AVOption of the mpegvideo
       * encoders
       */
      attribute_deprecated
      int error_rate;
  #endif
  
  #if FF_API_CODEC_PKT
      /**
       * @deprecated this field is not supposed to be accessed from outside lavc
       */
      attribute_deprecated
      AVPacket *pkt;
  #endif
  
      /**
       * VBV delay coded in the last frame (in periods of a 27 MHz clock).
       * Used for compliant TS muxing.
       * - encoding: Set by libavcodec.
       * - decoding: unused.
       */
      uint64_t vbv_delay;
  
      /**
       * Encoding only. Allow encoders to output packets that do not contain any
       * encoded data, only side data.
       *
       * Some encoders need to output such packets, e.g. to update some stream
       * parameters at the end of encoding.
       *
       * All callers are strongly recommended to set this option to 1 and update
       * their code to deal with such packets, since this behaviour may become
       * always enabled in the future (then this option will be deprecated and
       * later removed). To avoid ABI issues when this happens, the callers should
       * use AVOptions to set this field.
       */
      int side_data_only_packets;
  
      /**
       * Audio only. The number of "priming" samples (padding) inserted by the
       * encoder at the beginning of the audio. I.e. this number of leading
       * decoded samples must be discarded by the caller to get the original audio
       * without leading padding.
       *
       * - decoding: unused
       * - encoding: Set by libavcodec. The timestamps on the output packets are
       *             adjusted by the encoder so that they always refer to the
       *             first sample of the data actually contained in the packet,
       *             including any added padding.  E.g. if the timebase is
       *             1/samplerate and the timestamp of the first input sample is
       *             0, the timestamp of the first output packet will be
       *             -initial_padding.
       */
      int initial_padding;
  
      /**
       * - decoding: For codecs that store a framerate value in the compressed
       *             bitstream, the decoder may export it here. { 0, 1} when
       *             unknown.
       * - encoding: unused
       */
      AVRational framerate;
  
      /**
       * Timebase in which pkt_dts/pts and AVPacket.dts/pts are.
       * Code outside libavcodec should access this field using:
       * av_codec_{get,set}_pkt_timebase(avctx)
       * - encoding unused.
       * - decoding set by user.
       */
      AVRational pkt_timebase;
  
      /**
       * AVCodecDescriptor
       * Code outside libavcodec should access this field using:
       * av_codec_{get,set}_codec_descriptor(avctx)
       * - encoding: unused.
       * - decoding: set by libavcodec.
       */
      const AVCodecDescriptor *codec_descriptor;
  
  #if !FF_API_LOWRES
      /**
       * low resolution decoding, 1-> 1/2 size, 2->1/4 size
       * - encoding: unused
       * - decoding: Set by user.
       * Code outside libavcodec should access this field using:
       * av_codec_{get,set}_lowres(avctx)
       */
       int lowres;
  #endif
  
      /**
       * Current statistics for PTS correction.
       * - decoding: maintained and used by libavcodec, not intended to be used by user apps
       * - encoding: unused
       */
      int64_t pts_correction_num_faulty_pts; /// Number of incorrect PTS values so far
      int64_t pts_correction_num_faulty_dts; /// Number of incorrect DTS values so far
      int64_t pts_correction_last_pts;       /// PTS of the last frame
      int64_t pts_correction_last_dts;       /// DTS of the last frame
  
      /**
       * Character encoding of the input subtitles file.
       * - decoding: set by user
       * - encoding: unused
       */
      char *sub_charenc;
  
      /**
       * Subtitles character encoding mode. Formats or codecs might be adjusting
       * this setting (if they are doing the conversion themselves for instance).
       * - decoding: set by libavcodec
       * - encoding: unused
       */
      int sub_charenc_mode;
  #define FF_SUB_CHARENC_MODE_DO_NOTHING  -1  ///< do nothing (demuxer outputs a stream supposed to be already in UTF-8, or the codec is bitmap for instance)
  #define FF_SUB_CHARENC_MODE_AUTOMATIC    0  ///< libavcodec will select the mode itself
  #define FF_SUB_CHARENC_MODE_PRE_DECODER  1  ///< the AVPacket data needs to be recoded to UTF-8 before being fed to the decoder, requires iconv
  
      /**
       * Skip processing alpha if supported by codec.
       * Note that if the format uses pre-multiplied alpha (common with VP6,
       * and recommended due to better video quality/compression)
       * the image will look as if alpha-blended onto a black background.
       * However for formats that do not use pre-multiplied alpha
       * there might be serious artefacts (though e.g. libswscale currently
       * assumes pre-multiplied alpha anyway).
       * Code outside libavcodec should access this field using AVOptions
       *
       * - decoding: set by user
       * - encoding: unused
       */
      int skip_alpha;
  
      /**
       * Number of samples to skip after a discontinuity
       * - decoding: unused
       * - encoding: set by libavcodec
       */
      int seek_preroll;
  
  #if !FF_API_DEBUG_MV
      /**
       * debug motion vectors
       * Code outside libavcodec should access this field using AVOptions
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      int debug_mv;
  #define FF_DEBUG_VIS_MV_P_FOR  0x00000001 //visualize forward predicted MVs of P frames
  #define FF_DEBUG_VIS_MV_B_FOR  0x00000002 //visualize forward predicted MVs of B frames
  #define FF_DEBUG_VIS_MV_B_BACK 0x00000004 //visualize backward predicted MVs of B frames
  #endif
  
      /**
       * custom intra quantization matrix
       * Code outside libavcodec should access this field using av_codec_g/set_chroma_intra_matrix()
       * - encoding: Set by user, can be NULL.
       * - decoding: unused.
       */
      uint16_t *chroma_intra_matrix;
  
      /**
       * dump format separator.
       * can be ", " or "\n      " or anything else
       * Code outside libavcodec should access this field using AVOptions
       * (NO direct access).
       * - encoding: Set by user.
       * - decoding: Set by user.
       */
      uint8_t *dump_separator;
  
      /**
       * ',' separated list of allowed decoders.
       * If NULL then all are allowed
       * - encoding: unused
       * - decoding: set by user through AVOPtions (NO direct access)
       */
      char *codec_whitelist;
  } AVCodecContext;
  
  AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);
  void       av_codec_set_pkt_timebase         (AVCodecContext *avctx, AVRational val);
  
  const AVCodecDescriptor *av_codec_get_codec_descriptor(const AVCodecContext *avctx);
  void                     av_codec_set_codec_descriptor(AVCodecContext *avctx, const AVCodecDescriptor *desc);
  
  int  av_codec_get_lowres(const AVCodecContext *avctx);
  void av_codec_set_lowres(AVCodecContext *avctx, int val);
  
  int  av_codec_get_seek_preroll(const AVCodecContext *avctx);
  void av_codec_set_seek_preroll(AVCodecContext *avctx, int val);
  
  uint16_t *av_codec_get_chroma_intra_matrix(const AVCodecContext *avctx);
  void av_codec_set_chroma_intra_matrix(AVCodecContext *avctx, uint16_t *val);
  
  /**
   * AVProfile.
   */
  typedef struct AVProfile {
      int profile;
      const char *name; ///< short name for the profile
  } AVProfile;
  
  typedef struct AVCodecDefault AVCodecDefault;
  
  struct AVSubtitle;
  
  /**
   * AVCodec.
   */
  typedef struct AVCodec {
      /**
       * Name of the codec implementation.
       * The name is globally unique among encoders and among decoders (but an
       * encoder and a decoder can share the same name).
       * This is the primary way to find a codec from the user perspective.
       */
      const char *name;
      /**
       * Descriptive name for the codec, meant to be more human readable than name.
       * You should use the NULL_IF_CONFIG_SMALL() macro to define it.
       */
      const char *long_name;
      enum AVMediaType type;
      enum AVCodecID id;
      /**
       * Codec capabilities.
       * see CODEC_CAP_*
       */
      int capabilities;
      const AVRational *supported_framerates; ///< array of supported framerates, or NULL if any, array is terminated by {0,0}
      const enum AVPixelFormat *pix_fmts;     ///< array of supported pixel formats, or NULL if unknown, array is terminated by -1
      const int *supported_samplerates;       ///< array of supported audio samplerates, or NULL if unknown, array is terminated by 0
      const enum AVSampleFormat *sample_fmts; ///< array of supported sample formats, or NULL if unknown, array is terminated by -1
      const uint64_t *channel_layouts;         ///< array of support channel layouts, or NULL if unknown. array is terminated by 0
  #if FF_API_LOWRES
      uint8_t max_lowres;                     ///< maximum value for lowres supported by the decoder, no direct access, use av_codec_get_max_lowres()
  #endif
      const AVClass *priv_class;              ///< AVClass for the private context
      const AVProfile *profiles;              ///< array of recognized profiles, or NULL if unknown, array is terminated by {FF_PROFILE_UNKNOWN}
  
      /*****************************************************************
       * No fields below this line are part of the public API. They
       * may not be used outside of libavcodec and can be changed and
       * removed at will.
       * New public fields should be added right above.
       *****************************************************************
       */
      int priv_data_size;
      struct AVCodec *next;
      /**
       * @name Frame-level threading support functions
       * @{
       */
      /**
       * If defined, called on thread contexts when they are created.
       * If the codec allocates writable tables in init(), re-allocate them here.
       * priv_data will be set to a copy of the original.
       */
      int (*init_thread_copy)(AVCodecContext *);
      /**
       * Copy necessary context variables from a previous thread context to the current one.
       * If not defined, the next thread will start automatically; otherwise, the codec
       * must call ff_thread_finish_setup().
       *
       * dst and src will (rarely) point to the same context, in which case memcpy should be skipped.
       */
      int (*update_thread_context)(AVCodecContext *dst, const AVCodecContext *src);
      /** @} */
  
      /**
       * Private codec-specific defaults.
       */
      const AVCodecDefault *defaults;
  
      /**
       * Initialize codec static data, called from avcodec_register().
       */
      void (*init_static_data)(struct AVCodec *codec);
  
      int (*init)(AVCodecContext *);
      int (*encode_sub)(AVCodecContext *, uint8_t *buf, int buf_size,
                        const struct AVSubtitle *sub);
      /**
       * Encode data to an AVPacket.
       *
       * @param      avctx          codec context
       * @param      avpkt          output AVPacket (may contain a user-provided buffer)
       * @param[in]  frame          AVFrame containing the raw data to be encoded
       * @param[out] got_packet_ptr encoder sets to 0 or 1 to indicate that a
       *                            non-empty packet was returned in avpkt.
       * @return 0 on success, negative error code on failure
       */
      int (*encode2)(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame,
                     int *got_packet_ptr);
      int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
      int (*close)(AVCodecContext *);
      /**
       * Flush buffers.
       * Will be called when seeking
       */
      void (*flush)(AVCodecContext *);
  } AVCodec;
  
  int av_codec_get_max_lowres(const AVCodec *codec);
  
  struct MpegEncContext;
  
  /**
   * @defgroup lavc_hwaccel AVHWAccel
   * @{
   */
  typedef struct AVHWAccel {
      /**
       * Name of the hardware accelerated codec.
       * The name is globally unique among encoders and among decoders (but an
       * encoder and a decoder can share the same name).
       */
      const char *name;
  
      /**
       * Type of codec implemented by the hardware accelerator.
       *
       * See AVMEDIA_TYPE_xxx
       */
      enum AVMediaType type;
  
      /**
       * Codec implemented by the hardware accelerator.
       *
       * See AV_CODEC_ID_xxx
       */
      enum AVCodecID id;
  
      /**
       * Supported pixel format.
       *
       * Only hardware accelerated formats are supported here.
       */
      enum AVPixelFormat pix_fmt;
  
      /**
       * Hardware accelerated codec capabilities.
       * see FF_HWACCEL_CODEC_CAP_*
       */
      int capabilities;
  
      /*****************************************************************
       * No fields below this line are part of the public API. They
       * may not be used outside of libavcodec and can be changed and
       * removed at will.
       * New public fields should be added right above.
       *****************************************************************
       */
      struct AVHWAccel *next;
  
      /**
       * Allocate a custom buffer
       */
      int (*alloc_frame)(AVCodecContext *avctx, AVFrame *frame);
  
      /**
       * Called at the beginning of each frame or field picture.
       *
       * Meaningful frame information (codec specific) is guaranteed to
       * be parsed at this point. This function is mandatory.
       *
       * Note that buf can be NULL along with buf_size set to 0.
       * Otherwise, this means the whole frame is available at this point.
       *
       * @param avctx the codec context
       * @param buf the frame data buffer base
       * @param buf_size the size of the frame in bytes
       * @return zero if successful, a negative value otherwise
       */
      int (*start_frame)(AVCodecContext *avctx, const uint8_t *buf, uint32_t buf_size);
  
      /**
       * Callback for each slice.
       *
       * Meaningful slice information (codec specific) is guaranteed to
       * be parsed at this point. This function is mandatory.
       * The only exception is XvMC, that works on MB level.
       *
       * @param avctx the codec context
       * @param buf the slice data buffer base
       * @param buf_size the size of the slice in bytes
       * @return zero if successful, a negative value otherwise
       */
      int (*decode_slice)(AVCodecContext *avctx, const uint8_t *buf, uint32_t buf_size);
  
      /**
       * Called at the end of each frame or field picture.
       *
       * The whole picture is parsed at this point and can now be sent
       * to the hardware accelerator. This function is mandatory.
       *
       * @param avctx the codec context
       * @return zero if successful, a negative value otherwise
       */
      int (*end_frame)(AVCodecContext *avctx);
  
      /**
       * Size of per-frame hardware accelerator private data.
       *
       * Private data is allocated with av_mallocz() before
       * AVCodecContext.get_buffer() and deallocated after
       * AVCodecContext.release_buffer().
       */
      int frame_priv_data_size;
  
      /**
       * Called for every Macroblock in a slice.
       *
       * XvMC uses it to replace the ff_mpv_decode_mb().
       * Instead of decoding to raw picture, MB parameters are
       * stored in an array provided by the video driver.
       *
       * @param s the mpeg context
       */
      void (*decode_mb)(struct MpegEncContext *s);
  
      /**
       * Initialize the hwaccel private data.
       *
       * This will be called from ff_get_format(), after hwaccel and
       * hwaccel_context are set and the hwaccel private data in AVCodecInternal
       * is allocated.
       */
      int (*init)(AVCodecContext *avctx);
  
      /**
       * Uninitialize the hwaccel private data.
       *
       * This will be called from get_format() or avcodec_close(), after hwaccel
       * and hwaccel_context are already uninitialized.
       */
      int (*uninit)(AVCodecContext *avctx);
  
      /**
       * Size of the private data to allocate in
       * AVCodecInternal.hwaccel_priv_data.
       */
      int priv_data_size;
  } AVHWAccel;
  
  /**
   * Hardware acceleration should be used for decoding even if the codec level
   * used is unknown or higher than the maximum supported level reported by the
   * hardware driver.
   */
  #define AV_HWACCEL_FLAG_IGNORE_LEVEL (1 << 0)
  
  /**
   * @}
   */
  
  /**
   * @defgroup lavc_picture AVPicture
   *
   * Functions for working with AVPicture
   * @{
   */
  
  /**
   * Picture data structure.
   *
   * Up to four components can be stored into it, the last component is
   * alpha.
   */
  typedef struct AVPicture {
      uint8_t *data[AV_NUM_DATA_POINTERS];    ///< pointers to the image data planes
      int linesize[AV_NUM_DATA_POINTERS];     ///< number of bytes per line
  } AVPicture;
  
  /**
   * @}
   */
  
  enum AVSubtitleType {
      SUBTITLE_NONE,
  
      SUBTITLE_BITMAP,                ///< A bitmap, pict will be set
  
      /**
       * Plain text, the text field must be set by the decoder and is
       * authoritative. ass and pict fields may contain approximations.
       */
      SUBTITLE_TEXT,
  
      /**
       * Formatted text, the ass field must be set by the decoder and is
       * authoritative. pict and text fields may contain approximations.
       */
      SUBTITLE_ASS,
  };
  
  #define AV_SUBTITLE_FLAG_FORCED 0x00000001
  
  typedef struct AVSubtitleRect {
      int x;         ///< top left corner  of pict, undefined when pict is not set
      int y;         ///< top left corner  of pict, undefined when pict is not set
      int w;         ///< width            of pict, undefined when pict is not set
      int h;         ///< height           of pict, undefined when pict is not set
      int nb_colors; ///< number of colors in pict, undefined when pict is not set
  
      /**
       * data+linesize for the bitmap of this subtitle.
       * can be set for text/ass as well once they where rendered
       */
      AVPicture pict;
      enum AVSubtitleType type;
  
      char *text;                     ///< 0 terminated plain UTF-8 text
  
      /**
       * 0 terminated ASS/SSA compatible event line.
       * The presentation of this is unaffected by the other values in this
       * struct.
       */
      char *ass;
  
      int flags;
  } AVSubtitleRect;
  
  typedef struct AVSubtitle {
      uint16_t format; /* 0 = graphics */
      uint32_t start_display_time; /* relative to packet pts, in ms */
      uint32_t end_display_time; /* relative to packet pts, in ms */
      unsigned num_rects;
      AVSubtitleRect **rects;
      int64_t pts;    ///< Same as packet pts, in AV_TIME_BASE
  } AVSubtitle;
  
  /**
   * If c is NULL, returns the first registered codec,
   * if c is non-NULL, returns the next registered codec after c,
   * or NULL if c is the last one.
   */
  AVCodec *av_codec_next(const AVCodec *c);
  
  /**
   * Return the LIBAVCODEC_VERSION_INT constant.
   */
  unsigned avcodec_version(void);
  
  /**
   * Return the libavcodec build-time configuration.
   */
  const char *avcodec_configuration(void);
  
  /**
   * Return the libavcodec license.
   */
  const char *avcodec_license(void);
  
  /**
   * Register the codec codec and initialize libavcodec.
   *
   * @warning either this function or avcodec_register_all() must be called
   * before any other libavcodec functions.
   *
   * @see avcodec_register_all()
   */
  void avcodec_register(AVCodec *codec);
  
  /**
   * Register all the codecs, parsers and bitstream filters which were enabled at
   * configuration time. If you do not call this function you can select exactly
   * which formats you want to support, by using the individual registration
   * functions.
   *
   * @see avcodec_register
   * @see av_register_codec_parser
   * @see av_register_bitstream_filter
   */
  void avcodec_register_all(void);
  
  /**
   * Allocate an AVCodecContext and set its fields to default values. The
   * resulting struct should be freed with avcodec_free_context().
   *
   * @param codec if non-NULL, allocate private data and initialize defaults
   *              for the given codec. It is illegal to then call avcodec_open2()
   *              with a different codec.
   *              If NULL, then the codec-specific defaults won't be initialized,
   *              which may result in suboptimal default settings (this is
   *              important mainly for encoders, e.g. libx264).
   *
   * @return An AVCodecContext filled with default values or NULL on failure.
   * @see avcodec_get_context_defaults
   */
  AVCodecContext *avcodec_alloc_context3(const AVCodec *codec);
  
  /**
   * Free the codec context and everything associated with it and write NULL to
   * the provided pointer.
   */
  void avcodec_free_context(AVCodecContext **avctx);
  
  /**
   * Set the fields of the given AVCodecContext to default values corresponding
   * to the given codec (defaults may be codec-dependent).
   *
   * Do not call this function if a non-NULL codec has been passed
   * to avcodec_alloc_context3() that allocated this AVCodecContext.
   * If codec is non-NULL, it is illegal to call avcodec_open2() with a
   * different codec on this AVCodecContext.
   */
  int avcodec_get_context_defaults3(AVCodecContext *s, const AVCodec *codec);
  
  /**
   * Get the AVClass for AVCodecContext. It can be used in combination with
   * AV_OPT_SEARCH_FAKE_OBJ for examining options.
   *
   * @see av_opt_find().
   */
  const AVClass *avcodec_get_class(void);
  
  /**
   * Get the AVClass for AVFrame. It can be used in combination with
   * AV_OPT_SEARCH_FAKE_OBJ for examining options.
   *
   * @see av_opt_find().
   */
  const AVClass *avcodec_get_frame_class(void);
  
  /**
   * Get the AVClass for AVSubtitleRect. It can be used in combination with
   * AV_OPT_SEARCH_FAKE_OBJ for examining options.
   *
   * @see av_opt_find().
   */
  const AVClass *avcodec_get_subtitle_rect_class(void);
  
  /**
   * Copy the settings of the source AVCodecContext into the destination
   * AVCodecContext. The resulting destination codec context will be
   * unopened, i.e. you are required to call avcodec_open2() before you
   * can use this AVCodecContext to decode/encode video/audio data.
   *
   * @param dest target codec context, should be initialized with
   *             avcodec_alloc_context3(NULL), but otherwise uninitialized
   * @param src source codec context
   * @return AVERROR() on error (e.g. memory allocation error), 0 on success
   */
  int avcodec_copy_context(AVCodecContext *dest, const AVCodecContext *src);
  
  #if FF_API_AVFRAME_LAVC
  /**
   * @deprecated use av_frame_alloc()
   */
  attribute_deprecated
  AVFrame *avcodec_alloc_frame(void);
  
  /**
   * Set the fields of the given AVFrame to default values.
   *
   * @param frame The AVFrame of which the fields should be set to default values.
   *
   * @deprecated use av_frame_unref()
   */
  attribute_deprecated
  void avcodec_get_frame_defaults(AVFrame *frame);
  
  /**
   * Free the frame and any dynamically allocated objects in it,
   * e.g. extended_data.
   *
   * @param frame frame to be freed. The pointer will be set to NULL.
   *
   * @warning this function does NOT free the data buffers themselves
   * (it does not know how, since they might have been allocated with
   *  a custom get_buffer()).
   *
   * @deprecated use av_frame_free()
   */
  attribute_deprecated
  void avcodec_free_frame(AVFrame **frame);
  #endif
  
  /**
   * Initialize the AVCodecContext to use the given AVCodec. Prior to using this
   * function the context has to be allocated with avcodec_alloc_context3().
   *
   * The functions avcodec_find_decoder_by_name(), avcodec_find_encoder_by_name(),
   * avcodec_find_decoder() and avcodec_find_encoder() provide an easy way for
   * retrieving a codec.
   *
   * @warning This function is not thread safe!
   *
   * @code
   * avcodec_register_all();
   * av_dict_set(&opts, "b", "2.5M", 0);
   * codec = avcodec_find_decoder(AV_CODEC_ID_H264);
   * if (!codec)
   *     exit(1);
   *
   * context = avcodec_alloc_context3(codec);
   *
   * if (avcodec_open2(context, codec, opts) < 0)
   *     exit(1);
   * @endcode
   *
   * @param avctx The context to initialize.
   * @param codec The codec to open this context for. If a non-NULL codec has been
   *              previously passed to avcodec_alloc_context3() or
   *              avcodec_get_context_defaults3() for this context, then this
   *              parameter MUST be either NULL or equal to the previously passed
   *              codec.
   * @param options A dictionary filled with AVCodecContext and codec-private options.
   *                On return this object will be filled with options that were not found.
   *
   * @return zero on success, a negative value on error
   * @see avcodec_alloc_context3(), avcodec_find_decoder(), avcodec_find_encoder(),
   *      av_dict_set(), av_opt_find().
   */
  int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options);
  
  /**
   * Close a given AVCodecContext and free all the data associated with it
   * (but not the AVCodecContext itself).
   *
   * Calling this function on an AVCodecContext that hasn't been opened will free
   * the codec-specific data allocated in avcodec_alloc_context3() /
   * avcodec_get_context_defaults3() with a non-NULL codec. Subsequent calls will
   * do nothing.
   */
  int avcodec_close(AVCodecContext *avctx);
  
  /**
   * Free all allocated data in the given subtitle struct.
   *
   * @param sub AVSubtitle to free.
   */
  void avsubtitle_free(AVSubtitle *sub);
  
  /**
   * @}
   */
  
  /**
   * @addtogroup lavc_packet
   * @{
   */
  
  #if FF_API_DESTRUCT_PACKET
  /**
   * Default packet destructor.
   * @deprecated use the AVBuffer API instead
   */
  attribute_deprecated
  void av_destruct_packet(AVPacket *pkt);
  #endif
  
  /**
   * Initialize optional fields of a packet with default values.
   *
   * Note, this does not touch the data and size members, which have to be
   * initialized separately.
   *
   * @param pkt packet
   */
  void av_init_packet(AVPacket *pkt);
  
  /**
   * Allocate the payload of a packet and initialize its fields with
   * default values.
   *
   * @param pkt packet
   * @param size wanted payload size
   * @return 0 if OK, AVERROR_xxx otherwise
   */
  int av_new_packet(AVPacket *pkt, int size);
  
  /**
   * Reduce packet size, correctly zeroing padding
   *
   * @param pkt packet
   * @param size new size
   */
  void av_shrink_packet(AVPacket *pkt, int size);
  
  /**
   * Increase packet size, correctly zeroing padding
   *
   * @param pkt packet
   * @param grow_by number of bytes by which to increase the size of the packet
   */
  int av_grow_packet(AVPacket *pkt, int grow_by);
  
  /**
   * Initialize a reference-counted packet from av_malloc()ed data.
   *
   * @param pkt packet to be initialized. This function will set the data, size,
   *        buf and destruct fields, all others are left untouched.
   * @param data Data allocated by av_malloc() to be used as packet data. If this
   *        function returns successfully, the data is owned by the underlying AVBuffer.
   *        The caller may not access the data through other means.
   * @param size size of data in bytes, without the padding. I.e. the full buffer
   *        size is assumed to be size + FF_INPUT_BUFFER_PADDING_SIZE.
   *
   * @return 0 on success, a negative AVERROR on error
   */
  int av_packet_from_data(AVPacket *pkt, uint8_t *data, int size);
  
  /**
   * @warning This is a hack - the packet memory allocation stuff is broken. The
   * packet is allocated if it was not really allocated.
   */
  int av_dup_packet(AVPacket *pkt);
  
  /**
   * Copy packet, including contents
   *
   * @return 0 on success, negative AVERROR on fail
   */
  int av_copy_packet(AVPacket *dst, const AVPacket *src);
  
  /**
   * Copy packet side data
   *
   * @return 0 on success, negative AVERROR on fail
   */
  int av_copy_packet_side_data(AVPacket *dst, const AVPacket *src);
  
  /**
   * Free a packet.
   *
   * @param pkt packet to free
   */
  void av_free_packet(AVPacket *pkt);
  
  /**
   * Allocate new information of a packet.
   *
   * @param pkt packet
   * @param type side information type
   * @param size side information size
   * @return pointer to fresh allocated data or NULL otherwise
   */
  uint8_t* av_packet_new_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                   int size);
  
  /**
   * Shrink the already allocated side data buffer
   *
   * @param pkt packet
   * @param type side information type
   * @param size new side information size
   * @return 0 on success, < 0 on failure
   */
  int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                 int size);
  
  /**
   * Get side information from packet.
   *
   * @param pkt packet
   * @param type desired side information type
   * @param size pointer for side information size to store (optional)
   * @return pointer to data if present or NULL otherwise
   */
  uint8_t* av_packet_get_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                   int *size);
  
  int av_packet_merge_side_data(AVPacket *pkt);
  
  int av_packet_split_side_data(AVPacket *pkt);
  
  /**
   * Pack a dictionary for use in side_data.
   *
   * @param dict The dictionary to pack.
   * @param size pointer to store the size of the returned data
   * @return pointer to data if successful, NULL otherwise
   */
  uint8_t *av_packet_pack_dictionary(AVDictionary *dict, int *size);
  /**
   * Unpack a dictionary from side_data.
   *
   * @param data data from side_data
   * @param size size of the data
   * @param dict the metadata storage dictionary
   * @return 0 on success, < 0 on failure
   */
  int av_packet_unpack_dictionary(const uint8_t *data, int size, AVDictionary **dict);
  
  
  /**
   * Convenience function to free all the side data stored.
   * All the other fields stay untouched.
   *
   * @param pkt packet
   */
  void av_packet_free_side_data(AVPacket *pkt);
  
  /**
   * Setup a new reference to the data described by a given packet
   *
   * If src is reference-counted, setup dst as a new reference to the
   * buffer in src. Otherwise allocate a new buffer in dst and copy the
   * data from src into it.
   *
   * All the other fields are copied from src.
   *
   * @see av_packet_unref
   *
   * @param dst Destination packet
   * @param src Source packet
   *
   * @return 0 on success, a negative AVERROR on error.
   */
  int av_packet_ref(AVPacket *dst, const AVPacket *src);
  
  /**
   * Wipe the packet.
   *
   * Unreference the buffer referenced by the packet and reset the
   * remaining packet fields to their default values.
   *
   * @param pkt The packet to be unreferenced.
   */
  void av_packet_unref(AVPacket *pkt);
  
  /**
   * Move every field in src to dst and reset src.
   *
   * @see av_packet_unref
   *
   * @param src Source packet, will be reset
   * @param dst Destination packet
   */
  void av_packet_move_ref(AVPacket *dst, AVPacket *src);
  
  /**
   * Copy only "properties" fields from src to dst.
   *
   * Properties for the purpose of this function are all the fields
   * beside those related to the packet data (buf, data, size)
   *
   * @param dst Destination packet
   * @param src Source packet
   *
   * @return 0 on success AVERROR on failure.
   *
   */
  int av_packet_copy_props(AVPacket *dst, const AVPacket *src);
  
  /**
   * Convert valid timing fields (timestamps / durations) in a packet from one
   * timebase to another. Timestamps with unknown values (AV_NOPTS_VALUE) will be
   * ignored.
   *
   * @param pkt packet on which the conversion will be performed
   * @param tb_src source timebase, in which the timing fields in pkt are
   *               expressed
   * @param tb_dst destination timebase, to which the timing fields will be
   *               converted
   */
  void av_packet_rescale_ts(AVPacket *pkt, AVRational tb_src, AVRational tb_dst);
  
  /**
   * @}
   */
  
  /**
   * @addtogroup lavc_decoding
   * @{
   */
  
  /**
   * Find a registered decoder with a matching codec ID.
   *
   * @param id AVCodecID of the requested decoder
   * @return A decoder if one was found, NULL otherwise.
   */
  AVCodec *avcodec_find_decoder(enum AVCodecID id);
  
  /**
   * Find a registered decoder with the specified name.
   *
   * @param name name of the requested decoder
   * @return A decoder if one was found, NULL otherwise.
   */
  AVCodec *avcodec_find_decoder_by_name(const char *name);
  
  #if FF_API_GET_BUFFER
  attribute_deprecated int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic);
  attribute_deprecated void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic);
  attribute_deprecated int avcodec_default_reget_buffer(AVCodecContext *s, AVFrame *pic);
  #endif
  
  /**
   * The default callback for AVCodecContext.get_buffer2(). It is made public so
   * it can be called by custom get_buffer2() implementations for decoders without
   * CODEC_CAP_DR1 set.
   */
  int avcodec_default_get_buffer2(AVCodecContext *s, AVFrame *frame, int flags);
  
  #if FF_API_EMU_EDGE
  /**
   * Return the amount of padding in pixels which the get_buffer callback must
   * provide around the edge of the image for codecs which do not have the
   * CODEC_FLAG_EMU_EDGE flag.
   *
   * @return Required padding in pixels.
   *
   * @deprecated CODEC_FLAG_EMU_EDGE is deprecated, so this function is no longer
   * needed
   */
  attribute_deprecated
  unsigned avcodec_get_edge_width(void);
  #endif
  
  /**
   * Modify width and height values so that they will result in a memory
   * buffer that is acceptable for the codec if you do not use any horizontal
   * padding.
   *
   * May only be used if a codec with CODEC_CAP_DR1 has been opened.
   */
  void avcodec_align_dimensions(AVCodecContext *s, int *width, int *height);
  
  /**
   * Modify width and height values so that they will result in a memory
   * buffer that is acceptable for the codec if you also ensure that all
   * line sizes are a multiple of the respective linesize_align[i].
   *
   * May only be used if a codec with CODEC_CAP_DR1 has been opened.
   */
  void avcodec_align_dimensions2(AVCodecContext *s, int *width, int *height,
                                 int linesize_align[AV_NUM_DATA_POINTERS]);
  
  /**
   * Converts AVChromaLocation to swscale x/y chroma position.
   *
   * The positions represent the chroma (0,0) position in a coordinates system
   * with luma (0,0) representing the origin and luma(1,1) representing 256,256
   *
   * @param xpos  horizontal chroma sample position
   * @param ypos  vertical   chroma sample position
   */
  int avcodec_enum_to_chroma_pos(int *xpos, int *ypos, enum AVChromaLocation pos);
  
  /**
   * Converts swscale x/y chroma position to AVChromaLocation.
   *
   * The positions represent the chroma (0,0) position in a coordinates system
   * with luma (0,0) representing the origin and luma(1,1) representing 256,256
   *
   * @param xpos  horizontal chroma sample position
   * @param ypos  vertical   chroma sample position
   */
  enum AVChromaLocation avcodec_chroma_pos_to_enum(int xpos, int ypos);
  
  #if FF_API_OLD_DECODE_AUDIO
  /**
   * Wrapper function which calls avcodec_decode_audio4.
   *
   * @deprecated Use avcodec_decode_audio4 instead.
   *
   * Decode the audio frame of size avpkt->size from avpkt->data into samples.
   * Some decoders may support multiple frames in a single AVPacket, such
   * decoders would then just decode the first frame. In this case,
   * avcodec_decode_audio3 has to be called again with an AVPacket that contains
   * the remaining data in order to decode the second frame etc.
   * If no frame
   * could be outputted, frame_size_ptr is zero. Otherwise, it is the
   * decompressed frame size in bytes.
   *
   * @warning You must set frame_size_ptr to the allocated size of the
   * output buffer before calling avcodec_decode_audio3().
   *
   * @warning The input buffer must be FF_INPUT_BUFFER_PADDING_SIZE larger than
   * the actual read bytes because some optimized bitstream readers read 32 or 64
   * bits at once and could read over the end.
   *
   * @warning The end of the input buffer avpkt->data should be set to 0 to ensure that
   * no overreading happens for damaged MPEG streams.
   *
   * @warning You must not provide a custom get_buffer() when using
   * avcodec_decode_audio3().  Doing so will override it with
   * avcodec_default_get_buffer.  Use avcodec_decode_audio4() instead,
   * which does allow the application to provide a custom get_buffer().
   *
   * @note You might have to align the input buffer avpkt->data and output buffer
   * samples. The alignment requirements depend on the CPU: On some CPUs it isn't
   * necessary at all, on others it won't work at all if not aligned and on others
   * it will work but it will have an impact on performance.
   *
   * In practice, avpkt->data should have 4 byte alignment at minimum and
   * samples should be 16 byte aligned unless the CPU doesn't need it
   * (AltiVec and SSE do).
   *
   * @note Codecs which have the CODEC_CAP_DELAY capability set have a delay
   * between input and output, these need to be fed with avpkt->data=NULL,
   * avpkt->size=0 at the end to return the remaining frames.
   *
   * @param avctx the codec context
   * @param[out] samples the output buffer, sample type in avctx->sample_fmt
   *                     If the sample format is planar, each channel plane will
   *                     be the same size, with no padding between channels.
   * @param[in,out] frame_size_ptr the output buffer size in bytes
   * @param[in] avpkt The input AVPacket containing the input buffer.
   *            You can create such packet with av_init_packet() and by then setting
   *            data and size, some decoders might in addition need other fields.
   *            All decoders are designed to use the least fields possible though.
   * @return On error a negative value is returned, otherwise the number of bytes
   * used or zero if no frame data was decompressed (used) from the input AVPacket.
   */
  attribute_deprecated int avcodec_decode_audio3(AVCodecContext *avctx, int16_t *samples,
                           int *frame_size_ptr,
                           AVPacket *avpkt);
  #endif
  
  /**
   * Decode the audio frame of size avpkt->size from avpkt->data into frame.
   *
   * Some decoders may support multiple frames in a single AVPacket. Such
   * decoders would then just decode the first frame and the return value would be
   * less than the packet size. In this case, avcodec_decode_audio4 has to be
   * called again with an AVPacket containing the remaining data in order to
   * decode the second frame, etc...  Even if no frames are returned, the packet
   * needs to be fed to the decoder with remaining data until it is completely
   * consumed or an error occurs.
   *
   * Some decoders (those marked with CODEC_CAP_DELAY) have a delay between input
   * and output. This means that for some packets they will not immediately
   * produce decoded output and need to be flushed at the end of decoding to get
   * all the decoded data. Flushing is done by calling this function with packets
   * with avpkt->data set to NULL and avpkt->size set to 0 until it stops
   * returning samples. It is safe to flush even those decoders that are not
   * marked with CODEC_CAP_DELAY, then no samples will be returned.
   *
   * @warning The input buffer, avpkt->data must be FF_INPUT_BUFFER_PADDING_SIZE
   *          larger than the actual read bytes because some optimized bitstream
   *          readers read 32 or 64 bits at once and could read over the end.
   *
   * @param      avctx the codec context
   * @param[out] frame The AVFrame in which to store decoded audio samples.
   *                   The decoder will allocate a buffer for the decoded frame by
   *                   calling the AVCodecContext.get_buffer2() callback.
   *                   When AVCodecContext.refcounted_frames is set to 1, the frame is
   *                   reference counted and the returned reference belongs to the
   *                   caller. The caller must release the frame using av_frame_unref()
   *                   when the frame is no longer needed. The caller may safely write
   *                   to the frame if av_frame_is_writable() returns 1.
   *                   When AVCodecContext.refcounted_frames is set to 0, the returned
   *                   reference belongs to the decoder and is valid only until the
   *                   next call to this function or until closing or flushing the
   *                   decoder. The caller may not write to it.
   * @param[out] got_frame_ptr Zero if no frame could be decoded, otherwise it is
   *                           non-zero. Note that this field being set to zero
   *                           does not mean that an error has occurred. For
   *                           decoders with CODEC_CAP_DELAY set, no given decode
   *                           call is guaranteed to produce a frame.
   * @param[in]  avpkt The input AVPacket containing the input buffer.
   *                   At least avpkt->data and avpkt->size should be set. Some
   *                   decoders might also require additional fields to be set.
   * @return A negative error code is returned if an error occurred during
   *         decoding, otherwise the number of bytes consumed from the input
   *         AVPacket is returned.
   */
  int avcodec_decode_audio4(AVCodecContext *avctx, AVFrame *frame,
                            int *got_frame_ptr, const AVPacket *avpkt);
  
  /**
   * Decode the video frame of size avpkt->size from avpkt->data into picture.
   * Some decoders may support multiple frames in a single AVPacket, such
   * decoders would then just decode the first frame.
   *
   * @warning The input buffer must be FF_INPUT_BUFFER_PADDING_SIZE larger than
   * the actual read bytes because some optimized bitstream readers read 32 or 64
   * bits at once and could read over the end.
   *
   * @warning The end of the input buffer buf should be set to 0 to ensure that
   * no overreading happens for damaged MPEG streams.
   *
   * @note Codecs which have the CODEC_CAP_DELAY capability set have a delay
   * between input and output, these need to be fed with avpkt->data=NULL,
   * avpkt->size=0 at the end to return the remaining frames.
   *
   * @param avctx the codec context
   * @param[out] picture The AVFrame in which the decoded video frame will be stored.
   *             Use av_frame_alloc() to get an AVFrame. The codec will
   *             allocate memory for the actual bitmap by calling the
   *             AVCodecContext.get_buffer2() callback.
   *             When AVCodecContext.refcounted_frames is set to 1, the frame is
   *             reference counted and the returned reference belongs to the
   *             caller. The caller must release the frame using av_frame_unref()
   *             when the frame is no longer needed. The caller may safely write
   *             to the frame if av_frame_is_writable() returns 1.
   *             When AVCodecContext.refcounted_frames is set to 0, the returned
   *             reference belongs to the decoder and is valid only until the
   *             next call to this function or until closing or flushing the
   *             decoder. The caller may not write to it.
   *
   * @param[in] avpkt The input AVPacket containing the input buffer.
   *            You can create such packet with av_init_packet() and by then setting
   *            data and size, some decoders might in addition need other fields like
   *            flags&AV_PKT_FLAG_KEY. All decoders are designed to use the least
   *            fields possible.
   * @param[in,out] got_picture_ptr Zero if no frame could be decompressed, otherwise, it is nonzero.
   * @return On error a negative value is returned, otherwise the number of bytes
   * used or zero if no frame could be decompressed.
   */
  int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture,
                           int *got_picture_ptr,
                           const AVPacket *avpkt);
  
  /**
   * Decode a subtitle message.
   * Return a negative value on error, otherwise return the number of bytes used.
   * If no subtitle could be decompressed, got_sub_ptr is zero.
   * Otherwise, the subtitle is stored in *sub.
   * Note that CODEC_CAP_DR1 is not available for subtitle codecs. This is for
   * simplicity, because the performance difference is expect to be negligible
   * and reusing a get_buffer written for video codecs would probably perform badly
   * due to a potentially very different allocation pattern.
   *
   * Some decoders (those marked with CODEC_CAP_DELAY) have a delay between input
   * and output. This means that for some packets they will not immediately
   * produce decoded output and need to be flushed at the end of decoding to get
   * all the decoded data. Flushing is done by calling this function with packets
   * with avpkt->data set to NULL and avpkt->size set to 0 until it stops
   * returning subtitles. It is safe to flush even those decoders that are not
   * marked with CODEC_CAP_DELAY, then no subtitles will be returned.
   *
   * @param avctx the codec context
   * @param[out] sub The Preallocated AVSubtitle in which the decoded subtitle will be stored,
   *                 must be freed with avsubtitle_free if *got_sub_ptr is set.
   * @param[in,out] got_sub_ptr Zero if no subtitle could be decompressed, otherwise, it is nonzero.
   * @param[in] avpkt The input AVPacket containing the input buffer.
   */
  int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
                              int *got_sub_ptr,
                              AVPacket *avpkt);
  
  /**
   * @defgroup lavc_parsing Frame parsing
   * @{
   */
  
  enum AVPictureStructure {
      AV_PICTURE_STRUCTURE_UNKNOWN,      //< unknown
      AV_PICTURE_STRUCTURE_TOP_FIELD,    //< coded as top field
      AV_PICTURE_STRUCTURE_BOTTOM_FIELD, //< coded as bottom field
      AV_PICTURE_STRUCTURE_FRAME,        //< coded as frame
  };
  
  typedef struct AVCodecParserContext {
      void *priv_data;
      struct AVCodecParser *parser;
      int64_t frame_offset; /* offset of the current frame */
      int64_t cur_offset; /* current offset
                             (incremented by each av_parser_parse()) */
      int64_t next_frame_offset; /* offset of the next frame */
      /* video info */
      int pict_type; /* XXX: Put it back in AVCodecContext. */
      /**
       * This field is used for proper frame duration computation in lavf.
       * It signals, how much longer the frame duration of the current frame
       * is compared to normal frame duration.
       *
       * frame_duration = (1 + repeat_pict) * time_base
       *
       * It is used by codecs like H.264 to display telecined material.
       */
      int repeat_pict; /* XXX: Put it back in AVCodecContext. */
      int64_t pts;     /* pts of the current frame */
      int64_t dts;     /* dts of the current frame */
  
      /* private data */
      int64_t last_pts;
      int64_t last_dts;
      int fetch_timestamp;
  
  #define AV_PARSER_PTS_NB 4
      int cur_frame_start_index;
      int64_t cur_frame_offset[AV_PARSER_PTS_NB];
      int64_t cur_frame_pts[AV_PARSER_PTS_NB];
      int64_t cur_frame_dts[AV_PARSER_PTS_NB];
  
      int flags;
  #define PARSER_FLAG_COMPLETE_FRAMES           0x0001
  #define PARSER_FLAG_ONCE                      0x0002
  /// Set if the parser has a valid file offset
  #define PARSER_FLAG_FETCHED_OFFSET            0x0004
  #define PARSER_FLAG_USE_CODEC_TS              0x1000
  
      int64_t offset;      ///< byte offset from starting packet start
      int64_t cur_frame_end[AV_PARSER_PTS_NB];
  
      /**
       * Set by parser to 1 for key frames and 0 for non-key frames.
       * It is initialized to -1, so if the parser doesn't set this flag,
       * old-style fallback using AV_PICTURE_TYPE_I picture type as key frames
       * will be used.
       */
      int key_frame;
  
      /**
       * Time difference in stream time base units from the pts of this
       * packet to the point at which the output from the decoder has converged
       * independent from the availability of previous frames. That is, the
       * frames are virtually identical no matter if decoding started from
       * the very first frame or from this keyframe.
       * Is AV_NOPTS_VALUE if unknown.
       * This field is not the display duration of the current frame.
       * This field has no meaning if the packet does not have AV_PKT_FLAG_KEY
       * set.
       *
       * The purpose of this field is to allow seeking in streams that have no
       * keyframes in the conventional sense. It corresponds to the
       * recovery point SEI in H.264 and match_time_delta in NUT. It is also
       * essential for some types of subtitle streams to ensure that all
       * subtitles are correctly displayed after seeking.
       */
      int64_t convergence_duration;
  
      // Timestamp generation support:
      /**
       * Synchronization point for start of timestamp generation.
       *
       * Set to >0 for sync point, 0 for no sync point and <0 for undefined
       * (default).
       *
       * For example, this corresponds to presence of H.264 buffering period
       * SEI message.
       */
      int dts_sync_point;
  
      /**
       * Offset of the current timestamp against last timestamp sync point in
       * units of AVCodecContext.time_base.
       *
       * Set to INT_MIN when dts_sync_point unused. Otherwise, it must
       * contain a valid timestamp offset.
       *
       * Note that the timestamp of sync point has usually a nonzero
       * dts_ref_dts_delta, which refers to the previous sync point. Offset of
       * the next frame after timestamp sync point will be usually 1.
       *
       * For example, this corresponds to H.264 cpb_removal_delay.
       */
      int dts_ref_dts_delta;
  
      /**
       * Presentation delay of current frame in units of AVCodecContext.time_base.
       *
       * Set to INT_MIN when dts_sync_point unused. Otherwise, it must
       * contain valid non-negative timestamp delta (presentation time of a frame
       * must not lie in the past).
       *
       * This delay represents the difference between decoding and presentation
       * time of the frame.
       *
       * For example, this corresponds to H.264 dpb_output_delay.
       */
      int pts_dts_delta;
  
      /**
       * Position of the packet in file.
       *
       * Analogous to cur_frame_pts/dts
       */
      int64_t cur_frame_pos[AV_PARSER_PTS_NB];
  
      /**
       * Byte position of currently parsed frame in stream.
       */
      int64_t pos;
  
      /**
       * Previous frame byte position.
       */
      int64_t last_pos;
  
      /**
       * Duration of the current frame.
       * For audio, this is in units of 1 / AVCodecContext.sample_rate.
       * For all other types, this is in units of AVCodecContext.time_base.
       */
      int duration;
  
      enum AVFieldOrder field_order;
  
      /**
       * Indicate whether a picture is coded as a frame, top field or bottom field.
       *
       * For example, H.264 field_pic_flag equal to 0 corresponds to
       * AV_PICTURE_STRUCTURE_FRAME. An H.264 picture with field_pic_flag
       * equal to 1 and bottom_field_flag equal to 0 corresponds to
       * AV_PICTURE_STRUCTURE_TOP_FIELD.
       */
      enum AVPictureStructure picture_structure;
  
      /**
       * Picture number incremented in presentation or output order.
       * This field may be reinitialized at the first picture of a new sequence.
       *
       * For example, this corresponds to H.264 PicOrderCnt.
       */
      /*specific parameters export for H264 parsing, for the rest codec, 0 is default*/
      int output_picture_number;
      int frame_num;
      int max_frame_num_plus1;
      int width_in_pixel;
      int height_in_pixel;
      int frame_rate_num;
      int frame_rate_den;
      int frame_has_sps;
      int frame_has_pps;
  } AVCodecParserContext;
  
  typedef struct AVCodecParser {
      int codec_ids[5]; /* several codec IDs are permitted */
      int priv_data_size;
      int (*parser_init)(AVCodecParserContext *s);
      int (*parser_parse)(AVCodecParserContext *s,
                          AVCodecContext *avctx,
                          const uint8_t **poutbuf, int *poutbuf_size,
                          const uint8_t *buf, int buf_size);
      void (*parser_close)(AVCodecParserContext *s);
      int (*split)(AVCodecContext *avctx, const uint8_t *buf, int buf_size);
      struct AVCodecParser *next;
  } AVCodecParser;
  
  AVCodecParser *av_parser_next(const AVCodecParser *c);
  
  void av_register_codec_parser(AVCodecParser *parser);
  AVCodecParserContext *av_parser_init(int codec_id);
  
  /**
   * Parse a packet.
   *
   * @param s             parser context.
   * @param avctx         codec context.
   * @param poutbuf       set to pointer to parsed buffer or NULL if not yet finished.
   * @param poutbuf_size  set to size of parsed buffer or zero if not yet finished.
   * @param buf           input buffer.
   * @param buf_size      input length, to signal EOF, this should be 0 (so that the last frame can be output).
   * @param pts           input presentation timestamp.
   * @param dts           input decoding timestamp.
   * @param pos           input byte position in stream.
   * @return the number of bytes of the input bitstream used.
   *
   * Example:
   * @code
   *   while(in_len){
   *       len = av_parser_parse2(myparser, AVCodecContext, &data, &size,
   *                                        in_data, in_len,
   *                                        pts, dts, pos);
   *       in_data += len;
   *       in_len  -= len;
   *
   *       if(size)
   *          decode_frame(data, size);
   *   }
   * @endcode
   */
  int av_parser_parse2(AVCodecParserContext *s,
                       AVCodecContext *avctx,
                       uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size,
                       int64_t pts, int64_t dts,
                       int64_t pos);
  
  /**
   * @return 0 if the output buffer is a subset of the input, 1 if it is allocated and must be freed
   * @deprecated use AVBitStreamFilter
   */
  int av_parser_change(AVCodecParserContext *s,
                       AVCodecContext *avctx,
                       uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size, int keyframe);
  void av_parser_close(AVCodecParserContext *s);
  
  /**
   * @}
   * @}
   */
  
  /**
   * @addtogroup lavc_encoding
   * @{
   */
  
  /**
   * Find a registered encoder with a matching codec ID.
   *
   * @param id AVCodecID of the requested encoder
   * @return An encoder if one was found, NULL otherwise.
   */
  AVCodec *avcodec_find_encoder(enum AVCodecID id);
  
  /**
   * Find a registered encoder with the specified name.
   *
   * @param name name of the requested encoder
   * @return An encoder if one was found, NULL otherwise.
   */
  AVCodec *avcodec_find_encoder_by_name(const char *name);
  
  #if FF_API_OLD_ENCODE_AUDIO
  /**
   * Encode an audio frame from samples into buf.
   *
   * @deprecated Use avcodec_encode_audio2 instead.
   *
   * @note The output buffer should be at least FF_MIN_BUFFER_SIZE bytes large.
   * However, for codecs with avctx->frame_size equal to 0 (e.g. PCM) the user
   * will know how much space is needed because it depends on the value passed
   * in buf_size as described below. In that case a lower value can be used.
   *
   * @param avctx the codec context
   * @param[out] buf the output buffer
   * @param[in] buf_size the output buffer size
   * @param[in] samples the input buffer containing the samples
   * The number of samples read from this buffer is frame_size*channels,
   * both of which are defined in avctx.
   * For codecs which have avctx->frame_size equal to 0 (e.g. PCM) the number of
   * samples read from samples is equal to:
   * buf_size * 8 / (avctx->channels * av_get_bits_per_sample(avctx->codec_id))
   * This also implies that av_get_bits_per_sample() must not return 0 for these
   * codecs.
   * @return On error a negative value is returned, on success zero or the number
   * of bytes used to encode the data read from the input buffer.
   */
  int attribute_deprecated avcodec_encode_audio(AVCodecContext *avctx,
                                                uint8_t *buf, int buf_size,
                                                const short *samples);
  #endif
  
  /**
   * Encode a frame of audio.
   *
   * Takes input samples from frame and writes the next output packet, if
   * available, to avpkt. The output packet does not necessarily contain data for
   * the most recent frame, as encoders can delay, split, and combine input frames
   * internally as needed.
   *
   * @param avctx     codec context
   * @param avpkt     output AVPacket.
   *                  The user can supply an output buffer by setting
   *                  avpkt->data and avpkt->size prior to calling the
   *                  function, but if the size of the user-provided data is not
   *                  large enough, encoding will fail. If avpkt->data and
   *                  avpkt->size are set, avpkt->destruct must also be set. All
   *                  other AVPacket fields will be reset by the encoder using
   *                  av_init_packet(). If avpkt->data is NULL, the encoder will
   *                  allocate it. The encoder will set avpkt->size to the size
   *                  of the output packet.
   *
   *                  If this function fails or produces no output, avpkt will be
   *                  freed using av_free_packet() (i.e. avpkt->destruct will be
   *                  called to free the user supplied buffer).
   * @param[in] frame AVFrame containing the raw audio data to be encoded.
   *                  May be NULL when flushing an encoder that has the
   *                  CODEC_CAP_DELAY capability set.
   *                  If CODEC_CAP_VARIABLE_FRAME_SIZE is set, then each frame
   *                  can have any number of samples.
   *                  If it is not set, frame->nb_samples must be equal to
   *                  avctx->frame_size for all frames except the last.
   *                  The final frame may be smaller than avctx->frame_size.
   * @param[out] got_packet_ptr This field is set to 1 by libavcodec if the
   *                            output packet is non-empty, and to 0 if it is
   *                            empty. If the function returns an error, the
   *                            packet can be assumed to be invalid, and the
   *                            value of got_packet_ptr is undefined and should
   *                            not be used.
   * @return          0 on success, negative error code on failure
   */
  int avcodec_encode_audio2(AVCodecContext *avctx, AVPacket *avpkt,
                            const AVFrame *frame, int *got_packet_ptr);
  
  #if FF_API_OLD_ENCODE_VIDEO
  /**
   * @deprecated use avcodec_encode_video2() instead.
   *
   * Encode a video frame from pict into buf.
   * The input picture should be
   * stored using a specific format, namely avctx.pix_fmt.
   *
   * @param avctx the codec context
   * @param[out] buf the output buffer for the bitstream of encoded frame
   * @param[in] buf_size the size of the output buffer in bytes
   * @param[in] pict the input picture to encode
   * @return On error a negative value is returned, on success zero or the number
   * of bytes used from the output buffer.
   */
  attribute_deprecated
  int avcodec_encode_video(AVCodecContext *avctx, uint8_t *buf, int buf_size,
                           const AVFrame *pict);
  #endif
  
  /**
   * Encode a frame of video.
   *
   * Takes input raw video data from frame and writes the next output packet, if
   * available, to avpkt. The output packet does not necessarily contain data for
   * the most recent frame, as encoders can delay and reorder input frames
   * internally as needed.
   *
   * @param avctx     codec context
   * @param avpkt     output AVPacket.
   *                  The user can supply an output buffer by setting
   *                  avpkt->data and avpkt->size prior to calling the
   *                  function, but if the size of the user-provided data is not
   *                  large enough, encoding will fail. All other AVPacket fields
   *                  will be reset by the encoder using av_init_packet(). If
   *                  avpkt->data is NULL, the encoder will allocate it.
   *                  The encoder will set avpkt->size to the size of the
   *                  output packet. The returned data (if any) belongs to the
   *                  caller, he is responsible for freeing it.
   *
   *                  If this function fails or produces no output, avpkt will be
   *                  freed using av_free_packet() (i.e. avpkt->destruct will be
   *                  called to free the user supplied buffer).
   * @param[in] frame AVFrame containing the raw video data to be encoded.
   *                  May be NULL when flushing an encoder that has the
   *                  CODEC_CAP_DELAY capability set.
   * @param[out] got_packet_ptr This field is set to 1 by libavcodec if the
   *                            output packet is non-empty, and to 0 if it is
   *                            empty. If the function returns an error, the
   *                            packet can be assumed to be invalid, and the
   *                            value of got_packet_ptr is undefined and should
   *                            not be used.
   * @return          0 on success, negative error code on failure
   */
  int avcodec_encode_video2(AVCodecContext *avctx, AVPacket *avpkt,
                            const AVFrame *frame, int *got_packet_ptr);
  
  int avcodec_encode_subtitle(AVCodecContext *avctx, uint8_t *buf, int buf_size,
                              const AVSubtitle *sub);
  
  
  /**
   * @}
   */
  
  #if FF_API_AVCODEC_RESAMPLE
  /**
   * @defgroup lavc_resample Audio resampling
   * @ingroup libavc
   * @deprecated use libswresample instead
   *
   * @{
   */
  struct ReSampleContext;
  struct AVResampleContext;
  
  typedef struct ReSampleContext ReSampleContext;
  
  /**
   *  Initialize audio resampling context.
   *
   * @param output_channels  number of output channels
   * @param input_channels   number of input channels
   * @param output_rate      output sample rate
   * @param input_rate       input sample rate
   * @param sample_fmt_out   requested output sample format
   * @param sample_fmt_in    input sample format
   * @param filter_length    length of each FIR filter in the filterbank relative to the cutoff frequency
   * @param log2_phase_count log2 of the number of entries in the polyphase filterbank
   * @param linear           if 1 then the used FIR filter will be linearly interpolated
                             between the 2 closest, if 0 the closest will be used
   * @param cutoff           cutoff frequency, 1.0 corresponds to half the output sampling rate
   * @return allocated ReSampleContext, NULL if error occurred
   */
  attribute_deprecated
  ReSampleContext *av_audio_resample_init(int output_channels, int input_channels,
                                          int output_rate, int input_rate,
                                          enum AVSampleFormat sample_fmt_out,
                                          enum AVSampleFormat sample_fmt_in,
                                          int filter_length, int log2_phase_count,
                                          int linear, double cutoff);
  
  attribute_deprecated
  int audio_resample(ReSampleContext *s, short *output, short *input, int nb_samples);
  
  /**
   * Free resample context.
   *
   * @param s a non-NULL pointer to a resample context previously
   *          created with av_audio_resample_init()
   */
  attribute_deprecated
  void audio_resample_close(ReSampleContext *s);
  
  
  /**
   * Initialize an audio resampler.
   * Note, if either rate is not an integer then simply scale both rates up so they are.
   * @param filter_length length of each FIR filter in the filterbank relative to the cutoff freq
   * @param log2_phase_count log2 of the number of entries in the polyphase filterbank
   * @param linear If 1 then the used FIR filter will be linearly interpolated
                   between the 2 closest, if 0 the closest will be used
   * @param cutoff cutoff frequency, 1.0 corresponds to half the output sampling rate
   */
  attribute_deprecated
  struct AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_length, int log2_phase_count, int linear, double cutoff);
  
  /**
   * Resample an array of samples using a previously configured context.
   * @param src an array of unconsumed samples
   * @param consumed the number of samples of src which have been consumed are returned here
   * @param src_size the number of unconsumed samples available
   * @param dst_size the amount of space in samples available in dst
   * @param update_ctx If this is 0 then the context will not be modified, that way several channels can be resampled with the same context.
   * @return the number of samples written in dst or -1 if an error occurred
   */
  attribute_deprecated
  int av_resample(struct AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx);
  
  
  /**
   * Compensate samplerate/timestamp drift. The compensation is done by changing
   * the resampler parameters, so no audible clicks or similar distortions occur
   * @param compensation_distance distance in output samples over which the compensation should be performed
   * @param sample_delta number of output samples which should be output less
   *
   * example: av_resample_compensate(c, 10, 500)
   * here instead of 510 samples only 500 samples would be output
   *
   * note, due to rounding the actual compensation might be slightly different,
   * especially if the compensation_distance is large and the in_rate used during init is small
   */
  attribute_deprecated
  void av_resample_compensate(struct AVResampleContext *c, int sample_delta, int compensation_distance);
  attribute_deprecated
  void av_resample_close(struct AVResampleContext *c);
  
  /**
   * @}
   */
  #endif
  
  /**
   * @addtogroup lavc_picture
   * @{
   */
  
  /**
   * Allocate memory for the pixels of a picture and setup the AVPicture
   * fields for it.
   *
   * Call avpicture_free() to free it.
   *
   * @param picture            the picture structure to be filled in
   * @param pix_fmt            the pixel format of the picture
   * @param width              the width of the picture
   * @param height             the height of the picture
   * @return zero if successful, a negative error code otherwise
   *
   * @see av_image_alloc(), avpicture_fill()
   */
  int avpicture_alloc(AVPicture *picture, enum AVPixelFormat pix_fmt, int width, int height);
  
  /**
   * Free a picture previously allocated by avpicture_alloc().
   * The data buffer used by the AVPicture is freed, but the AVPicture structure
   * itself is not.
   *
   * @param picture the AVPicture to be freed
   */
  void avpicture_free(AVPicture *picture);
  
  /**
   * Setup the picture fields based on the specified image parameters
   * and the provided image data buffer.
   *
   * The picture fields are filled in by using the image data buffer
   * pointed to by ptr.
   *
   * If ptr is NULL, the function will fill only the picture linesize
   * array and return the required size for the image buffer.
   *
   * To allocate an image buffer and fill the picture data in one call,
   * use avpicture_alloc().
   *
   * @param picture       the picture to be filled in
   * @param ptr           buffer where the image data is stored, or NULL
   * @param pix_fmt       the pixel format of the image
   * @param width         the width of the image in pixels
   * @param height        the height of the image in pixels
   * @return the size in bytes required for src, a negative error code
   * in case of failure
   *
   * @see av_image_fill_arrays()
   */
  int avpicture_fill(AVPicture *picture, const uint8_t *ptr,
                     enum AVPixelFormat pix_fmt, int width, int height);
  
  /**
   * Copy pixel data from an AVPicture into a buffer.
   *
   * avpicture_get_size() can be used to compute the required size for
   * the buffer to fill.
   *
   * @param src        source picture with filled data
   * @param pix_fmt    picture pixel format
   * @param width      picture width
   * @param height     picture height
   * @param dest       destination buffer
   * @param dest_size  destination buffer size in bytes
   * @return the number of bytes written to dest, or a negative value
   * (error code) on error, for example if the destination buffer is not
   * big enough
   *
   * @see av_image_copy_to_buffer()
   */
  int avpicture_layout(const AVPicture *src, enum AVPixelFormat pix_fmt,
                       int width, int height,
                       unsigned char *dest, int dest_size);
  
  /**
   * Calculate the size in bytes that a picture of the given width and height
   * would occupy if stored in the given picture format.
   *
   * @param pix_fmt    picture pixel format
   * @param width      picture width
   * @param height     picture height
   * @return the computed picture buffer size or a negative error code
   * in case of error
   *
   * @see av_image_get_buffer_size().
   */
  int avpicture_get_size(enum AVPixelFormat pix_fmt, int width, int height);
  
  #if FF_API_DEINTERLACE
  /**
   *  deinterlace - if not supported return -1
   *
   * @deprecated - use yadif (in libavfilter) instead
   */
  attribute_deprecated
  int avpicture_deinterlace(AVPicture *dst, const AVPicture *src,
                            enum AVPixelFormat pix_fmt, int width, int height);
  #endif
  /**
   * Copy image src to dst. Wraps av_image_copy().
   */
  void av_picture_copy(AVPicture *dst, const AVPicture *src,
                       enum AVPixelFormat pix_fmt, int width, int height);
  
  /**
   * Crop image top and left side.
   */
  int av_picture_crop(AVPicture *dst, const AVPicture *src,
                      enum AVPixelFormat pix_fmt, int top_band, int left_band);
  
  /**
   * Pad image.
   */
  int av_picture_pad(AVPicture *dst, const AVPicture *src, int height, int width, enum AVPixelFormat pix_fmt,
              int padtop, int padbottom, int padleft, int padright, int *color);
  
  /**
   * @}
   */
  
  /**
   * @defgroup lavc_misc Utility functions
   * @ingroup libavc
   *
   * Miscellaneous utility functions related to both encoding and decoding
   * (or neither).
   * @{
   */
  
  /**
   * @defgroup lavc_misc_pixfmt Pixel formats
   *
   * Functions for working with pixel formats.
   * @{
   */
  
  /**
   * Utility function to access log2_chroma_w log2_chroma_h from
   * the pixel format AVPixFmtDescriptor.
   *
   * This function asserts that pix_fmt is valid. See av_pix_fmt_get_chroma_sub_sample
   * for one that returns a failure code and continues in case of invalid
   * pix_fmts.
   *
   * @param[in]  pix_fmt the pixel format
   * @param[out] h_shift store log2_chroma_w
   * @param[out] v_shift store log2_chroma_h
   *
   * @see av_pix_fmt_get_chroma_sub_sample
   */
  
  void avcodec_get_chroma_sub_sample(enum AVPixelFormat pix_fmt, int *h_shift, int *v_shift);
  
  /**
   * Return a value representing the fourCC code associated to the
   * pixel format pix_fmt, or 0 if no associated fourCC code can be
   * found.
   */
  unsigned int avcodec_pix_fmt_to_codec_tag(enum AVPixelFormat pix_fmt);
  
  /**
   * @deprecated see av_get_pix_fmt_loss()
   */
  int avcodec_get_pix_fmt_loss(enum AVPixelFormat dst_pix_fmt, enum AVPixelFormat src_pix_fmt,
                               int has_alpha);
  
  /**
   * Find the best pixel format to convert to given a certain source pixel
   * format.  When converting from one pixel format to another, information loss
   * may occur.  For example, when converting from RGB24 to GRAY, the color
   * information will be lost. Similarly, other losses occur when converting from
   * some formats to other formats. avcodec_find_best_pix_fmt_of_2() searches which of
   * the given pixel formats should be used to suffer the least amount of loss.
   * The pixel formats from which it chooses one, are determined by the
   * pix_fmt_list parameter.
   *
   *
   * @param[in] pix_fmt_list AV_PIX_FMT_NONE terminated array of pixel formats to choose from
   * @param[in] src_pix_fmt source pixel format
   * @param[in] has_alpha Whether the source pixel format alpha channel is used.
   * @param[out] loss_ptr Combination of flags informing you what kind of losses will occur.
   * @return The best pixel format to convert to or -1 if none was found.
   */
  enum AVPixelFormat avcodec_find_best_pix_fmt_of_list(const enum AVPixelFormat *pix_fmt_list,
                                              enum AVPixelFormat src_pix_fmt,
                                              int has_alpha, int *loss_ptr);
  
  /**
   * @deprecated see av_find_best_pix_fmt_of_2()
   */
  enum AVPixelFormat avcodec_find_best_pix_fmt_of_2(enum AVPixelFormat dst_pix_fmt1, enum AVPixelFormat dst_pix_fmt2,
                                              enum AVPixelFormat src_pix_fmt, int has_alpha, int *loss_ptr);
  
  attribute_deprecated
  #if AV_HAVE_INCOMPATIBLE_LIBAV_ABI
  enum AVPixelFormat avcodec_find_best_pix_fmt2(const enum AVPixelFormat *pix_fmt_list,
                                                enum AVPixelFormat src_pix_fmt,
                                                int has_alpha, int *loss_ptr);
  #else
  enum AVPixelFormat avcodec_find_best_pix_fmt2(enum AVPixelFormat dst_pix_fmt1, enum AVPixelFormat dst_pix_fmt2,
                                              enum AVPixelFormat src_pix_fmt, int has_alpha, int *loss_ptr);
  #endif
  
  
  enum AVPixelFormat avcodec_default_get_format(struct AVCodecContext *s, const enum AVPixelFormat * fmt);
  
  /**
   * @}
   */
  
  #if FF_API_SET_DIMENSIONS
  /**
   * @deprecated this function is not supposed to be used from outside of lavc
   */
  attribute_deprecated
  void avcodec_set_dimensions(AVCodecContext *s, int width, int height);
  #endif
  
  /**
   * Put a string representing the codec tag codec_tag in buf.
   *
   * @param buf       buffer to place codec tag in
   * @param buf_size size in bytes of buf
   * @param codec_tag codec tag to assign
   * @return the length of the string that would have been generated if
   * enough space had been available, excluding the trailing null
   */
  size_t av_get_codec_tag_string(char *buf, size_t buf_size, unsigned int codec_tag);
  
  void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode);
  
  /**
   * Return a name for the specified profile, if available.
   *
   * @param codec the codec that is searched for the given profile
   * @param profile the profile value for which a name is requested
   * @return A name for the profile if found, NULL otherwise.
   */
  const char *av_get_profile_name(const AVCodec *codec, int profile);
  
  int avcodec_default_execute(AVCodecContext *c, int (*func)(AVCodecContext *c2, void *arg2),void *arg, int *ret, int count, int size);
  int avcodec_default_execute2(AVCodecContext *c, int (*func)(AVCodecContext *c2, void *arg2, int, int),void *arg, int *ret, int count);
  //FIXME func typedef
  
  /**
   * Fill AVFrame audio data and linesize pointers.
   *
   * The buffer buf must be a preallocated buffer with a size big enough
   * to contain the specified samples amount. The filled AVFrame data
   * pointers will point to this buffer.
   *
   * AVFrame extended_data channel pointers are allocated if necessary for
   * planar audio.
   *
   * @param frame       the AVFrame
   *                    frame->nb_samples must be set prior to calling the
   *                    function. This function fills in frame->data,
   *                    frame->extended_data, frame->linesize[0].
   * @param nb_channels channel count
   * @param sample_fmt  sample format
   * @param buf         buffer to use for frame data
   * @param buf_size    size of buffer
   * @param align       plane size sample alignment (0 = default)
   * @return            >=0 on success, negative error code on failure
   * @todo return the size in bytes required to store the samples in
   * case of success, at the next libavutil bump
   */
  int avcodec_fill_audio_frame(AVFrame *frame, int nb_channels,
                               enum AVSampleFormat sample_fmt, const uint8_t *buf,
                               int buf_size, int align);
  
  /**
   * Reset the internal decoder state / flush internal buffers. Should be called
   * e.g. when seeking or when switching to a different stream.
   *
   * @note when refcounted frames are not used (i.e. avctx->refcounted_frames is 0),
   * this invalidates the frames previously returned from the decoder. When
   * refcounted frames are used, the decoder just releases any references it might
   * keep internally, but the caller's reference remains valid.
   */
  void avcodec_flush_buffers(AVCodecContext *avctx);
  
  /**
   * Return codec bits per sample.
   *
   * @param[in] codec_id the codec
   * @return Number of bits per sample or zero if unknown for the given codec.
   */
  int av_get_bits_per_sample(enum AVCodecID codec_id);
  
  /**
   * Return the PCM codec associated with a sample format.
   * @param be  endianness, 0 for little, 1 for big,
   *            -1 (or anything else) for native
   * @return  AV_CODEC_ID_PCM_* or AV_CODEC_ID_NONE
   */
  enum AVCodecID av_get_pcm_codec(enum AVSampleFormat fmt, int be);
  
  /**
   * Return codec bits per sample.
   * Only return non-zero if the bits per sample is exactly correct, not an
   * approximation.
   *
   * @param[in] codec_id the codec
   * @return Number of bits per sample or zero if unknown for the given codec.
   */
  int av_get_exact_bits_per_sample(enum AVCodecID codec_id);
  
  /**
   * Return audio frame duration.
   *
   * @param avctx        codec context
   * @param frame_bytes  size of the frame, or 0 if unknown
   * @return             frame duration, in samples, if known. 0 if not able to
   *                     determine.
   */
  int av_get_audio_frame_duration(AVCodecContext *avctx, int frame_bytes);
  
  
  typedef struct AVBitStreamFilterContext {
      void *priv_data;
      struct AVBitStreamFilter *filter;
      AVCodecParserContext *parser;
      struct AVBitStreamFilterContext *next;
  } AVBitStreamFilterContext;
  
  
  typedef struct AVBitStreamFilter {
      const char *name;
      int priv_data_size;
      int (*filter)(AVBitStreamFilterContext *bsfc,
                    AVCodecContext *avctx, const char *args,
                    uint8_t **poutbuf, int *poutbuf_size,
                    const uint8_t *buf, int buf_size, int keyframe);
      void (*close)(AVBitStreamFilterContext *bsfc);
      struct AVBitStreamFilter *next;
  } AVBitStreamFilter;
  
  /**
   * Register a bitstream filter.
   *
   * The filter will be accessible to the application code through
   * av_bitstream_filter_next() or can be directly initialized with
   * av_bitstream_filter_init().
   *
   * @see avcodec_register_all()
   */
  void av_register_bitstream_filter(AVBitStreamFilter *bsf);
  
  /**
   * Create and initialize a bitstream filter context given a bitstream
   * filter name.
   *
   * The returned context must be freed with av_bitstream_filter_close().
   *
   * @param name    the name of the bitstream filter
   * @return a bitstream filter context if a matching filter was found
   * and successfully initialized, NULL otherwise
   */
  AVBitStreamFilterContext *av_bitstream_filter_init(const char *name);
  
  /**
   * Filter bitstream.
   *
   * This function filters the buffer buf with size buf_size, and places the
   * filtered buffer in the buffer pointed to by poutbuf.
   *
   * The output buffer must be freed by the caller.
   *
   * @param bsfc            bitstream filter context created by av_bitstream_filter_init()
   * @param avctx           AVCodecContext accessed by the filter, may be NULL.
   *                        If specified, this must point to the encoder context of the
   *                        output stream the packet is sent to.
   * @param args            arguments which specify the filter configuration, may be NULL
   * @param poutbuf         pointer which is updated to point to the filtered buffer
   * @param poutbuf_size    pointer which is updated to the filtered buffer size in bytes
   * @param buf             buffer containing the data to filter
   * @param buf_size        size in bytes of buf
   * @param keyframe        set to non-zero if the buffer to filter corresponds to a key-frame packet data
   * @return >= 0 in case of success, or a negative error code in case of failure
   *
   * If the return value is positive, an output buffer is allocated and
   * is available in *poutbuf, and is distinct from the input buffer.
   *
   * If the return value is 0, the output buffer is not allocated and
   * should be considered identical to the input buffer, or in case
   * *poutbuf was set it points to the input buffer (not necessarily to
   * its starting address).
   */
  int av_bitstream_filter_filter(AVBitStreamFilterContext *bsfc,
                                 AVCodecContext *avctx, const char *args,
                                 uint8_t **poutbuf, int *poutbuf_size,
                                 const uint8_t *buf, int buf_size, int keyframe);
  
  /**
   * Release bitstream filter context.
   *
   * @param bsf the bitstream filter context created with
   * av_bitstream_filter_init(), can be NULL
   */
  void av_bitstream_filter_close(AVBitStreamFilterContext *bsf);
  
  /**
   * If f is NULL, return the first registered bitstream filter,
   * if f is non-NULL, return the next registered bitstream filter
   * after f, or NULL if f is the last one.
   *
   * This function can be used to iterate over all registered bitstream
   * filters.
   */
  AVBitStreamFilter *av_bitstream_filter_next(const AVBitStreamFilter *f);
  
  /* memory */
  
  /**
   * Same behaviour av_fast_malloc but the buffer has additional
   * FF_INPUT_BUFFER_PADDING_SIZE at the end which will always be 0.
   *
   * In addition the whole buffer will initially and after resizes
   * be 0-initialized so that no uninitialized data will ever appear.
   */
  void av_fast_padded_malloc(void *ptr, unsigned int *size, size_t min_size);
  
  /**
   * Same behaviour av_fast_padded_malloc except that buffer will always
   * be 0-initialized after call.
   */
  void av_fast_padded_mallocz(void *ptr, unsigned int *size, size_t min_size);
  
  /**
   * Encode extradata length to a buffer. Used by xiph codecs.
   *
   * @param s buffer to write to; must be at least (v/255+1) bytes long
   * @param v size of extradata in bytes
   * @return number of bytes written to the buffer.
   */
  unsigned int av_xiphlacing(unsigned char *s, unsigned int v);
  
  #if FF_API_MISSING_SAMPLE
  /**
   * Log a generic warning message about a missing feature. This function is
   * intended to be used internally by FFmpeg (libavcodec, libavformat, etc.)
   * only, and would normally not be used by applications.
   * @param[in] avc a pointer to an arbitrary struct of which the first field is
   * a pointer to an AVClass struct
   * @param[in] feature string containing the name of the missing feature
   * @param[in] want_sample indicates if samples are wanted which exhibit this feature.
   * If want_sample is non-zero, additional verbage will be added to the log
   * message which tells the user how to report samples to the development
   * mailing list.
   * @deprecated Use avpriv_report_missing_feature() instead.
   */
  attribute_deprecated
  void av_log_missing_feature(void *avc, const char *feature, int want_sample);
  
  /**
   * Log a generic warning message asking for a sample. This function is
   * intended to be used internally by FFmpeg (libavcodec, libavformat, etc.)
   * only, and would normally not be used by applications.
   * @param[in] avc a pointer to an arbitrary struct of which the first field is
   * a pointer to an AVClass struct
   * @param[in] msg string containing an optional message, or NULL if no message
   * @deprecated Use avpriv_request_sample() instead.
   */
  attribute_deprecated
  void av_log_ask_for_sample(void *avc, const char *msg, ...) av_printf_format(2, 3);
  #endif /* FF_API_MISSING_SAMPLE */
  
  /**
   * Register the hardware accelerator hwaccel.
   */
  void av_register_hwaccel(AVHWAccel *hwaccel);
  
  /**
   * If hwaccel is NULL, returns the first registered hardware accelerator,
   * if hwaccel is non-NULL, returns the next registered hardware accelerator
   * after hwaccel, or NULL if hwaccel is the last one.
   */
  AVHWAccel *av_hwaccel_next(const AVHWAccel *hwaccel);
  
  
  /**
   * Lock operation used by lockmgr
   */
  enum AVLockOp {
    AV_LOCK_CREATE,  ///< Create a mutex
    AV_LOCK_OBTAIN,  ///< Lock the mutex
    AV_LOCK_RELEASE, ///< Unlock the mutex
    AV_LOCK_DESTROY, ///< Free mutex resources
  };
  
  /**
   * Register a user provided lock manager supporting the operations
   * specified by AVLockOp. The "mutex" argument to the function points
   * to a (void *) where the lockmgr should store/get a pointer to a user
   * allocated mutex. It is NULL upon AV_LOCK_CREATE and equal to the
   * value left by the last call for all other ops. If the lock manager is
   * unable to perform the op then it should leave the mutex in the same
   * state as when it was called and return a non-zero value. However,
   * when called with AV_LOCK_DESTROY the mutex will always be assumed to
   * have been successfully destroyed. If av_lockmgr_register succeeds
   * it will return a non-negative value, if it fails it will return a
   * negative value and destroy all mutex and unregister all callbacks.
   * av_lockmgr_register is not thread-safe, it must be called from a
   * single thread before any calls which make use of locking are used.
   *
   * @param cb User defined callback. av_lockmgr_register invokes calls
   *           to this callback and the previously registered callback.
   *           The callback will be used to create more than one mutex
   *           each of which must be backed by its own underlying locking
   *           mechanism (i.e. do not use a single static object to
   *           implement your lock manager). If cb is set to NULL the
   *           lockmgr will be unregistered.
   */
  int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op));
  
  /**
   * Get the type of the given codec.
   */
  enum AVMediaType avcodec_get_type(enum AVCodecID codec_id);
  
  /**
   * Get the name of a codec.
   * @return  a static string identifying the codec; never NULL
   */
  const char *avcodec_get_name(enum AVCodecID id);
  
  /**
   * @return a positive value if s is open (i.e. avcodec_open2() was called on it
   * with no corresponding avcodec_close()), 0 otherwise.
   */
  int avcodec_is_open(AVCodecContext *s);
  
  /**
   * @return a non-zero number if codec is an encoder, zero otherwise
   */
  int av_codec_is_encoder(const AVCodec *codec);
  
  /**
   * @return a non-zero number if codec is a decoder, zero otherwise
   */
  int av_codec_is_decoder(const AVCodec *codec);
  
  /**
   * @return descriptor for given codec ID or NULL if no descriptor exists.
   */
  const AVCodecDescriptor *avcodec_descriptor_get(enum AVCodecID id);
  
  /**
   * Iterate over all codec descriptors known to libavcodec.
   *
   * @param prev previous descriptor. NULL to get the first descriptor.
   *
   * @return next descriptor or NULL after the last descriptor
   */
  const AVCodecDescriptor *avcodec_descriptor_next(const AVCodecDescriptor *prev);
  
  /**
   * @return codec descriptor with the given name or NULL if no such descriptor
   *         exists.
   */
  const AVCodecDescriptor *avcodec_descriptor_get_by_name(const char *name);
  
  /**
   * @}
   */
  
  #endif /* AVCODEC_AVCODEC_H */
  