text: /*
   * FLV muxer
   * Copyright (c) 2003 The FFmpeg Project
   *
   * 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
   */
  
  #include "libavutil/intreadwrite.h"
  #include "libavutil/dict.h"
  #include "libavutil/intfloat.h"
  #include "libavutil/avassert.h"
  #include "avc.h"
  #include "avformat.h"
  #include "flv.h"
  #include "internal.h"
  #include "metadata.h"
  
  
  static const AVCodecTag flv_video_codec_ids[] = {
      { AV_CODEC_ID_FLV1,     FLV_CODECID_H263 },
      { AV_CODEC_ID_H263,     FLV_CODECID_REALH263 },
      { AV_CODEC_ID_MPEG4,    FLV_CODECID_MPEG4 },
      { AV_CODEC_ID_FLASHSV,  FLV_CODECID_SCREEN },
      { AV_CODEC_ID_FLASHSV2, FLV_CODECID_SCREEN2 },
      { AV_CODEC_ID_VP6F,     FLV_CODECID_VP6 },
      { AV_CODEC_ID_VP6,      FLV_CODECID_VP6 },
      { AV_CODEC_ID_VP6A,     FLV_CODECID_VP6A },
      { AV_CODEC_ID_H264,     FLV_CODECID_H264 },
      { AV_CODEC_ID_NONE,     0 }
  };
  
  static const AVCodecTag flv_audio_codec_ids[] = {
      { AV_CODEC_ID_MP3,        FLV_CODECID_MP3        >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_PCM_U8,     FLV_CODECID_PCM        >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_PCM_S16BE,  FLV_CODECID_PCM        >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_PCM_S16LE,  FLV_CODECID_PCM_LE     >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_ADPCM_SWF,  FLV_CODECID_ADPCM      >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_AAC,        FLV_CODECID_AAC        >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_NELLYMOSER, FLV_CODECID_NELLYMOSER >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_PCM_MULAW,  FLV_CODECID_PCM_MULAW  >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_PCM_ALAW,   FLV_CODECID_PCM_ALAW   >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_SPEEX,      FLV_CODECID_SPEEX      >> FLV_AUDIO_CODECID_OFFSET },
      { AV_CODEC_ID_NONE,       0 }
  };
  
  typedef struct FLVContext {
      int     reserved;
      int64_t duration_offset;
      int64_t filesize_offset;
      int64_t duration;
      int64_t delay;      ///< first dts delay (needed for AVC & Speex)
  } FLVContext;
  
  typedef struct FLVStreamContext {
      int64_t last_ts;    ///< last timestamp for each stream
  } FLVStreamContext;
  
  static int get_audio_flags(AVFormatContext *s, AVCodecContext *enc)
  {
      int flags = (enc->bits_per_coded_sample == 16) ? FLV_SAMPLESSIZE_16BIT
                                                     : FLV_SAMPLESSIZE_8BIT;
  
      if (enc->codec_id == AV_CODEC_ID_AAC) // specs force these parameters
          return FLV_CODECID_AAC | FLV_SAMPLERATE_44100HZ |
                 FLV_SAMPLESSIZE_16BIT | FLV_STEREO;
      else if (enc->codec_id == AV_CODEC_ID_SPEEX) {
          if (enc->sample_rate != 16000) {
              av_log(s, AV_LOG_ERROR,
                     "FLV only supports wideband (16kHz) Speex audio\n");
              return AVERROR(EINVAL);
          }
          if (enc->channels != 1) {
              av_log(s, AV_LOG_ERROR, "FLV only supports mono Speex audio\n");
              return AVERROR(EINVAL);
          }
          return FLV_CODECID_SPEEX | FLV_SAMPLERATE_11025HZ | FLV_SAMPLESSIZE_16BIT;
      } else {
          switch (enc->sample_rate) {
          case 44100:
              flags |= FLV_SAMPLERATE_44100HZ;
              break;
          case 22050:
              flags |= FLV_SAMPLERATE_22050HZ;
              break;
          case 11025:
              flags |= FLV_SAMPLERATE_11025HZ;
              break;
          case 16000: // nellymoser only
          case  8000: // nellymoser only
          case  5512: // not MP3
              if (enc->codec_id != AV_CODEC_ID_MP3) {
                  flags |= FLV_SAMPLERATE_SPECIAL;
                  break;
              }
          default:
              av_log(s, AV_LOG_ERROR,
                     "FLV does not support sample rate %d, "
                     "choose from (44100, 22050, 11025)\n", enc->sample_rate);
              return AVERROR(EINVAL);
          }
      }
  
      if (enc->channels > 1)
          flags |= FLV_STEREO;
  
      switch (enc->codec_id) {
      case AV_CODEC_ID_MP3:
          flags |= FLV_CODECID_MP3    | FLV_SAMPLESSIZE_16BIT;
          break;
      case AV_CODEC_ID_PCM_U8:
          flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_8BIT;
          break;
      case AV_CODEC_ID_PCM_S16BE:
          flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_16BIT;
          break;
      case AV_CODEC_ID_PCM_S16LE:
          flags |= FLV_CODECID_PCM_LE | FLV_SAMPLESSIZE_16BIT;
          break;
      case AV_CODEC_ID_ADPCM_SWF:
          flags |= FLV_CODECID_ADPCM  | FLV_SAMPLESSIZE_16BIT;
          break;
      case AV_CODEC_ID_NELLYMOSER:
          if (enc->sample_rate == 8000)
              flags |= FLV_CODECID_NELLYMOSER_8KHZ_MONO  | FLV_SAMPLESSIZE_16BIT;
          else if (enc->sample_rate == 16000)
              flags |= FLV_CODECID_NELLYMOSER_16KHZ_MONO | FLV_SAMPLESSIZE_16BIT;
          else
              flags |= FLV_CODECID_NELLYMOSER            | FLV_SAMPLESSIZE_16BIT;
          break;
      case AV_CODEC_ID_PCM_MULAW:
          flags = FLV_CODECID_PCM_MULAW | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT;
          break;
      case AV_CODEC_ID_PCM_ALAW:
          flags = FLV_CODECID_PCM_ALAW  | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT;
          break;
      case 0:
          flags |= enc->codec_tag << 4;
          break;
      default:
          av_log(s, AV_LOG_ERROR, "Audio codec '%s' not compatible with FLV\n",
                 avcodec_get_name(enc->codec_id));
          return AVERROR(EINVAL);
      }
  
      return flags;
  }
  
  static void put_amf_string(AVIOContext *pb, const char *str)
  {
      size_t len = strlen(str);
      avio_wb16(pb, len);
      avio_write(pb, str, len);
  }
  
  static void put_avc_eos_tag(AVIOContext *pb, unsigned ts)
  {
      avio_w8(pb, FLV_TAG_TYPE_VIDEO);
      avio_wb24(pb, 5);               /* Tag Data Size */
      avio_wb24(pb, ts);              /* lower 24 bits of timestamp in ms */
      avio_w8(pb, (ts >> 24) & 0x7F); /* MSB of ts in ms */
      avio_wb24(pb, 0);               /* StreamId = 0 */
      avio_w8(pb, 23);                /* ub[4] FrameType = 1, ub[4] CodecId = 7 */
      avio_w8(pb, 2);                 /* AVC end of sequence */
      avio_wb24(pb, 0);               /* Always 0 for AVC EOS. */
      avio_wb32(pb, 16);              /* Size of FLV tag */
  }
  
  static void put_amf_double(AVIOContext *pb, double d)
  {
      avio_w8(pb, AMF_DATA_TYPE_NUMBER);
      avio_wb64(pb, av_double2int(d));
  }
  
  static void put_amf_bool(AVIOContext *pb, int b)
  {
      avio_w8(pb, AMF_DATA_TYPE_BOOL);
      avio_w8(pb, !!b);
  }
  
  static int flv_write_header(AVFormatContext *s)
  {
      AVIOContext *pb = s->pb;
      FLVContext *flv = s->priv_data;
      AVCodecContext *audio_enc = NULL, *video_enc = NULL, *data_enc = NULL;
      int i, metadata_count = 0;
      double framerate = 0.0;
      int64_t metadata_size_pos, data_size, metadata_count_pos;
      AVDictionaryEntry *tag = NULL;
  
      for (i = 0; i < s->nb_streams; i++) {
          AVCodecContext *enc = s->streams[i]->codec;
          FLVStreamContext *sc;
          switch (enc->codec_type) {
          case AVMEDIA_TYPE_VIDEO:
              if (s->streams[i]->avg_frame_rate.den &&
                  s->streams[i]->avg_frame_rate.num) {
                  framerate = av_q2d(s->streams[i]->avg_frame_rate);
              } else {
                  framerate = 1 / av_q2d(s->streams[i]->codec->time_base);
              }
              if (video_enc) {
                  av_log(s, AV_LOG_ERROR,
                         "at most one video stream is supported in flv\n");
                  return AVERROR(EINVAL);
              }
              video_enc = enc;
              if (enc->codec_tag == 0) {
                  av_log(s, AV_LOG_ERROR, "Video codec '%s' for stream %d is not compatible with FLV\n",
                         avcodec_get_name(enc->codec_id), i);
                  return AVERROR(EINVAL);
              }
              break;
          case AVMEDIA_TYPE_AUDIO:
              if (audio_enc) {
                  av_log(s, AV_LOG_ERROR,
                         "at most one audio stream is supported in flv\n");
                  return AVERROR(EINVAL);
              }
              audio_enc = enc;
              if (get_audio_flags(s, enc) < 0)
                  return AVERROR_INVALIDDATA;
              break;
          case AVMEDIA_TYPE_DATA:
              if (enc->codec_id != AV_CODEC_ID_TEXT) {
                  av_log(s, AV_LOG_ERROR, "Data codec '%s' for stream %d is not compatible with FLV\n",
                         avcodec_get_name(enc->codec_id), i);
                  return AVERROR_INVALIDDATA;
              }
              data_enc = enc;
              break;
          default:
              av_log(s, AV_LOG_ERROR, "Codec type '%s' for stream %d is not compatible with FLV\n",
                     av_get_media_type_string(enc->codec_type), i);
              return AVERROR(EINVAL);
          }
          avpriv_set_pts_info(s->streams[i], 32, 1, 1000); /* 32 bit pts in ms */
  
          sc = av_mallocz(sizeof(FLVStreamContext));
          if (!sc)
              return AVERROR(ENOMEM);
          s->streams[i]->priv_data = sc;
          sc->last_ts = -1;
      }
  
      flv->delay = AV_NOPTS_VALUE;
  
      avio_write(pb, "FLV", 3);
      avio_w8(pb, 1);
      avio_w8(pb, FLV_HEADER_FLAG_HASAUDIO * !!audio_enc +
                  FLV_HEADER_FLAG_HASVIDEO * !!video_enc);
      avio_wb32(pb, 9);
      avio_wb32(pb, 0);
  
      for (i = 0; i < s->nb_streams; i++)
          if (s->streams[i]->codec->codec_tag == 5) {
              avio_w8(pb, 8);     // message type
              avio_wb24(pb, 0);   // include flags
              avio_wb24(pb, 0);   // time stamp
              avio_wb32(pb, 0);   // reserved
              avio_wb32(pb, 11);  // size
              flv->reserved = 5;
          }
  
      /* write meta_tag */
      avio_w8(pb, 18);            // tag type META
      metadata_size_pos = avio_tell(pb);
      avio_wb24(pb, 0);           // size of data part (sum of all parts below)
      avio_wb24(pb, 0);           // timestamp
      avio_wb32(pb, 0);           // reserved
  
      /* now data of data_size size */
  
      /* first event name as a string */
      avio_w8(pb, AMF_DATA_TYPE_STRING);
      put_amf_string(pb, "onMetaData"); // 12 bytes
  
      /* mixed array (hash) with size and string/type/data tuples */
      avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);
      metadata_count_pos = avio_tell(pb);
      metadata_count = 5 * !!video_enc +
                       5 * !!audio_enc +
                       1 * !!data_enc  +
                       2; // +2 for duration and file size
  
      avio_wb32(pb, metadata_count);
  
      put_amf_string(pb, "duration");
      flv->duration_offset= avio_tell(pb);
  
      // fill in the guessed duration, it'll be corrected later if incorrect
      put_amf_double(pb, s->duration / AV_TIME_BASE);
  
      if (video_enc) {
          put_amf_string(pb, "width");
          put_amf_double(pb, video_enc->width);
  
          put_amf_string(pb, "height");
          put_amf_double(pb, video_enc->height);
  
          put_amf_string(pb, "videodatarate");
          put_amf_double(pb, video_enc->bit_rate / 1024.0);
  
          put_amf_string(pb, "framerate");
          put_amf_double(pb, framerate);
  
          put_amf_string(pb, "videocodecid");
          put_amf_double(pb, video_enc->codec_tag);
      }
  
      if (audio_enc) {
          put_amf_string(pb, "audiodatarate");
          put_amf_double(pb, audio_enc->bit_rate / 1024.0);
  
          put_amf_string(pb, "audiosamplerate");
          put_amf_double(pb, audio_enc->sample_rate);
  
          put_amf_string(pb, "audiosamplesize");
          put_amf_double(pb, audio_enc->codec_id == AV_CODEC_ID_PCM_U8 ? 8 : 16);
  
          put_amf_string(pb, "stereo");
          put_amf_bool(pb, audio_enc->channels == 2);
  
          put_amf_string(pb, "audiocodecid");
          put_amf_double(pb, audio_enc->codec_tag);
      }
  
      if (data_enc) {
          put_amf_string(pb, "datastream");
          put_amf_double(pb, 0.0);
      }
  
      while ((tag = av_dict_get(s->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {
          if(   !strcmp(tag->key, "width")
              ||!strcmp(tag->key, "height")
              ||!strcmp(tag->key, "videodatarate")
              ||!strcmp(tag->key, "framerate")
              ||!strcmp(tag->key, "videocodecid")
              ||!strcmp(tag->key, "audiodatarate")
              ||!strcmp(tag->key, "audiosamplerate")
              ||!strcmp(tag->key, "audiosamplesize")
              ||!strcmp(tag->key, "stereo")
              ||!strcmp(tag->key, "audiocodecid")
              ||!strcmp(tag->key, "duration")
              ||!strcmp(tag->key, "onMetaData")
          ){
              av_log(s, AV_LOG_DEBUG, "Ignoring metadata for %s\n", tag->key);
              continue;
          }
          put_amf_string(pb, tag->key);
          avio_w8(pb, AMF_DATA_TYPE_STRING);
          put_amf_string(pb, tag->value);
          metadata_count++;
      }
  
      put_amf_string(pb, "filesize");
      flv->filesize_offset = avio_tell(pb);
      put_amf_double(pb, 0); // delayed write
  
      put_amf_string(pb, "");
      avio_w8(pb, AMF_END_OF_OBJECT);
  
      /* write total size of tag */
      data_size = avio_tell(pb) - metadata_size_pos - 10;
  
      avio_seek(pb, metadata_count_pos, SEEK_SET);
      avio_wb32(pb, metadata_count);
  
      avio_seek(pb, metadata_size_pos, SEEK_SET);
      avio_wb24(pb, data_size);
      avio_skip(pb, data_size + 10 - 3);
      avio_wb32(pb, data_size + 11);
  
      for (i = 0; i < s->nb_streams; i++) {
          AVCodecContext *enc = s->streams[i]->codec;
          if (enc->codec_id == AV_CODEC_ID_AAC || enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) {
              int64_t pos;
              avio_w8(pb, enc->codec_type == AVMEDIA_TYPE_VIDEO ?
                      FLV_TAG_TYPE_VIDEO : FLV_TAG_TYPE_AUDIO);
              avio_wb24(pb, 0); // size patched later
              avio_wb24(pb, 0); // ts
              avio_w8(pb, 0);   // ts ext
              avio_wb24(pb, 0); // streamid
              pos = avio_tell(pb);
              if (enc->codec_id == AV_CODEC_ID_AAC) {
                  avio_w8(pb, get_audio_flags(s, enc));
                  avio_w8(pb, 0); // AAC sequence header
                  avio_write(pb, enc->extradata, enc->extradata_size);
              } else {
                  avio_w8(pb, enc->codec_tag | FLV_FRAME_KEY); // flags
                  avio_w8(pb, 0); // AVC sequence header
                  avio_wb24(pb, 0); // composition time
                  ff_isom_write_avcc(pb, enc->extradata, enc->extradata_size);
              }
              data_size = avio_tell(pb) - pos;
              avio_seek(pb, -data_size - 10, SEEK_CUR);
              avio_wb24(pb, data_size);
              avio_skip(pb, data_size + 10 - 3);
              avio_wb32(pb, data_size + 11); // previous tag size
          }
      }
  
      return 0;
  }
  
  static int flv_write_trailer(AVFormatContext *s)
  {
      int64_t file_size;
  
      AVIOContext *pb = s->pb;
      FLVContext *flv = s->priv_data;
      int i;
  
      /* Add EOS tag */
      for (i = 0; i < s->nb_streams; i++) {
          AVCodecContext *enc = s->streams[i]->codec;
          FLVStreamContext *sc = s->streams[i]->priv_data;
          if (enc->codec_type == AVMEDIA_TYPE_VIDEO &&
                  (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4))
              put_avc_eos_tag(pb, sc->last_ts);
      }
  
      file_size = avio_tell(pb);
  
      /* update information */
      if (avio_seek(pb, flv->duration_offset, SEEK_SET) < 0)
          av_log(s, AV_LOG_WARNING, "Failed to update header with correct duration.\n");
      else
          put_amf_double(pb, flv->duration / (double)1000);
      if (avio_seek(pb, flv->filesize_offset, SEEK_SET) < 0)
          av_log(s, AV_LOG_WARNING, "Failed to update header with correct filesize.\n");
      else
          put_amf_double(pb, file_size);
  
      avio_seek(pb, file_size, SEEK_SET);
      return 0;
  }
  
  static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
  {
      AVIOContext *pb      = s->pb;
      AVCodecContext *enc  = s->streams[pkt->stream_index]->codec;
      FLVContext *flv      = s->priv_data;
      FLVStreamContext *sc = s->streams[pkt->stream_index]->priv_data;
      unsigned ts;
      int size = pkt->size;
      uint8_t *data = NULL;
      int flags = -1, flags_size, ret;
  
      if (enc->codec_id == AV_CODEC_ID_VP6 || enc->codec_id == AV_CODEC_ID_VP6F ||
          enc->codec_id == AV_CODEC_ID_VP6A || enc->codec_id == AV_CODEC_ID_AAC)
          flags_size = 2;
      else if (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4)
          flags_size = 5;
      else
          flags_size = 1;
  
      switch (enc->codec_type) {
      case AVMEDIA_TYPE_VIDEO:
          avio_w8(pb, FLV_TAG_TYPE_VIDEO);
  
          flags = enc->codec_tag;
          if (flags == 0) {
              av_log(s, AV_LOG_ERROR,
                     "Video codec '%s' is not compatible with FLV\n",
                     avcodec_get_name(enc->codec_id));
              return AVERROR(EINVAL);
          }
  
          flags |= pkt->flags & AV_PKT_FLAG_KEY ? FLV_FRAME_KEY : FLV_FRAME_INTER;
          break;
      case AVMEDIA_TYPE_AUDIO:
          flags = get_audio_flags(s, enc);
  
          av_assert0(size);
  
          avio_w8(pb, FLV_TAG_TYPE_AUDIO);
          break;
      case AVMEDIA_TYPE_DATA:
          avio_w8(pb, FLV_TAG_TYPE_META);
          break;
      default:
          return AVERROR(EINVAL);
      }
  
      if (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) {
          /* check if extradata looks like mp4 formated */
          if (enc->extradata_size > 0 && *(uint8_t*)enc->extradata != 1)
              if ((ret = ff_avc_parse_nal_units_buf(pkt->data, &data, &size)) < 0)
                  return ret;
      } else if (enc->codec_id == AV_CODEC_ID_AAC && pkt->size > 2 &&
                 (AV_RB16(pkt->data) & 0xfff0) == 0xfff0) {
          if (!s->streams[pkt->stream_index]->nb_frames) {
          av_log(s, AV_LOG_ERROR, "Malformed AAC bitstream detected: "
                 "use audio bitstream filter 'aac_adtstoasc' to fix it "
                 "('-bsf:a aac_adtstoasc' option with ffmpeg)\n");
          return AVERROR_INVALIDDATA;
          }
          av_log(s, AV_LOG_WARNING, "aac bitstream error\n");
      }
  
      if (flv->delay == AV_NOPTS_VALUE)
          flv->delay = -pkt->dts;
  
      if (pkt->dts < -flv->delay) {
          av_log(s, AV_LOG_WARNING,
                 "Packets are not in the proper order with respect to DTS\n");
          return AVERROR(EINVAL);
      }
  
      ts = pkt->dts + flv->delay; // add delay to force positive dts
  
      /* check Speex packet duration */
      if (enc->codec_id == AV_CODEC_ID_SPEEX && ts - sc->last_ts > 160)
          av_log(s, AV_LOG_WARNING, "Warning: Speex stream has more than "
                                    "8 frames per packet. Adobe Flash "
                                    "Player cannot handle this!\n");
  
      if (sc->last_ts < ts)
          sc->last_ts = ts;
  
      avio_wb24(pb, size + flags_size);
      avio_wb24(pb, ts);
      avio_w8(pb, (ts >> 24) & 0x7F); // timestamps are 32 bits _signed_
      avio_wb24(pb, flv->reserved);
  
      if (enc->codec_type == AVMEDIA_TYPE_DATA) {
          int data_size;
          int metadata_size_pos = avio_tell(pb);
          avio_w8(pb, AMF_DATA_TYPE_STRING);
          put_amf_string(pb, "onTextData");
          avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);
          avio_wb32(pb, 2);
          put_amf_string(pb, "type");
          avio_w8(pb, AMF_DATA_TYPE_STRING);
          put_amf_string(pb, "Text");
          put_amf_string(pb, "text");
          avio_w8(pb, AMF_DATA_TYPE_STRING);
          put_amf_string(pb, pkt->data);
          put_amf_string(pb, "");
          avio_w8(pb, AMF_END_OF_OBJECT);
          /* write total size of tag */
          data_size = avio_tell(pb) - metadata_size_pos;
          avio_seek(pb, metadata_size_pos - 10, SEEK_SET);
          avio_wb24(pb, data_size);
          avio_seek(pb, data_size + 10 - 3, SEEK_CUR);
          avio_wb32(pb, data_size + 11);
      } else {
          av_assert1(flags>=0);
          avio_w8(pb,flags);
          if (enc->codec_id == AV_CODEC_ID_VP6)
              avio_w8(pb,0);
          if (enc->codec_id == AV_CODEC_ID_VP6F || enc->codec_id == AV_CODEC_ID_VP6A)
              avio_w8(pb, enc->extradata_size ? enc->extradata[0] : 0);
          else if (enc->codec_id == AV_CODEC_ID_AAC)
              avio_w8(pb,1); // AAC raw
          else if (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) {
              avio_w8(pb,1); // AVC NALU
              avio_wb24(pb,pkt->pts - pkt->dts);
          }
  
          avio_write(pb, data ? data : pkt->data, size);
  
          avio_wb32(pb, size + flags_size + 11); // previous tag size
          flv->duration = FFMAX(flv->duration,
                                pkt->pts + flv->delay + pkt->duration);
      }
  
      av_free(data);
  
      return pb->error;
  }
  
  AVOutputFormat ff_flv_muxer = {
      .name           = "flv",
      .long_name      = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"),
      .mime_type      = "video/x-flv",
      .extensions     = "flv",
      .priv_data_size = sizeof(FLVContext),
      .audio_codec    = CONFIG_LIBMP3LAME ? AV_CODEC_ID_MP3 : AV_CODEC_ID_ADPCM_SWF,
      .video_codec    = AV_CODEC_ID_FLV1,
      .write_header   = flv_write_header,
      .write_packet   = flv_write_packet,
      .write_trailer  = flv_write_trailer,
      .codec_tag      = (const AVCodecTag* const []) {
                            flv_video_codec_ids, flv_audio_codec_ids, 0
                        },
      .flags          = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS |
                        AVFMT_TS_NONSTRICT,
  };
  