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
   */
  
  /**
   * @file
   * mpeg audio declarations for both encoder and decoder.
   */
  
  #ifndef AVCODEC_MPEGAUDIO_H
  #define AVCODEC_MPEGAUDIO_H
  
  #ifndef CONFIG_FLOAT
  #   define CONFIG_FLOAT 0
  #endif
  
  #include "avcodec.h"
  #include "get_bits.h"
  #include "dsputil.h"
  #include "fft.h"
  
  #define CONFIG_AUDIO_NONSHORT 0
  
  /* max frame size, in samples */
  #define MPA_FRAME_SIZE 1152
  
  /* max compressed frame size */
  #define MPA_MAX_CODED_FRAME_SIZE 1792
  
  #define MPA_MAX_CHANNELS 2
  
  #define SBLIMIT 32 /* number of subbands */
  
  #define MPA_STEREO  0
  #define MPA_JSTEREO 1
  #define MPA_DUAL    2
  #define MPA_MONO    3
  
  /* header + layer + bitrate + freq + lsf/mpeg25 */
  #define SAME_HEADER_MASK \
     (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))
  
  #define MP3_MASK 0xFFFE0CCF
  
  #if CONFIG_MPEGAUDIO_HP
  #define FRAC_BITS   23   /* fractional bits for sb_samples and dct */
  #define WFRAC_BITS  16   /* fractional bits for window */
  #else
  #define FRAC_BITS   15   /* fractional bits for sb_samples and dct */
  #define WFRAC_BITS  14   /* fractional bits for window */
  #endif
  
  #define FRAC_ONE    (1 << FRAC_BITS)
  
  #define FIX(a)   ((int)((a) * FRAC_ONE))
  
  #if CONFIG_FLOAT
  typedef float OUT_INT;
  #define OUT_FMT SAMPLE_FMT_FLT
  #elif CONFIG_MPEGAUDIO_HP && CONFIG_AUDIO_NONSHORT
  typedef int32_t OUT_INT;
  #define OUT_MAX INT32_MAX
  #define OUT_MIN INT32_MIN
  #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 31)
  #define OUT_FMT SAMPLE_FMT_S32
  #else
  typedef int16_t OUT_INT;
  #define OUT_MAX INT16_MAX
  #define OUT_MIN INT16_MIN
  #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)
  #define OUT_FMT SAMPLE_FMT_S16
  #endif
  
  #if CONFIG_FLOAT
  #   define INTFLOAT float
  typedef float MPA_INT;
  #elif FRAC_BITS <= 15
  #   define INTFLOAT int
  typedef int16_t MPA_INT;
  #else
  #   define INTFLOAT int
  typedef int32_t MPA_INT;
  #endif
  
  #define BACKSTEP_SIZE 512
  #define EXTRABYTES 24
  
  /* layer 3 "granule" */
  typedef struct GranuleDef {
      uint8_t scfsi;
      int part2_3_length;
      int big_values;
      int global_gain;
      int scalefac_compress;
      uint8_t block_type;
      uint8_t switch_point;
      int table_select[3];
      int subblock_gain[3];
      uint8_t scalefac_scale;
      uint8_t count1table_select;
      int region_size[3]; /* number of huffman codes in each region */
      int preflag;
      int short_start, long_end; /* long/short band indexes */
      uint8_t scale_factors[40];
      INTFLOAT sb_hybrid[SBLIMIT * 18]; /* 576 samples */
  } GranuleDef;
  
  #define MPA_DECODE_HEADER \
      int frame_size; \
      int error_protection; \
      int layer; \
      int sample_rate; \
      int sample_rate_index; /* between 0 and 8 */ \
      int bit_rate; \
      int nb_channels; \
      int mode; \
      int mode_ext; \
      int lsf;
  
  typedef struct MPADecodeHeader {
    MPA_DECODE_HEADER
  } MPADecodeHeader;
  
  typedef struct MPADecodeContext {
      MPA_DECODE_HEADER
      uint8_t last_buf[2*BACKSTEP_SIZE + EXTRABYTES];
      int last_buf_size;
      /* next header (used in free format parsing) */
      uint32_t free_format_next_header;
      GetBitContext gb;
      GetBitContext in_gb;
      DECLARE_ALIGNED(16, MPA_INT, synth_buf)[MPA_MAX_CHANNELS][512 * 2];
      int synth_buf_offset[MPA_MAX_CHANNELS];
      DECLARE_ALIGNED(16, INTFLOAT, sb_samples)[MPA_MAX_CHANNELS][36][SBLIMIT];
      INTFLOAT mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */
      GranuleDef granules[2][2]; /* Used in Layer 3 */
  #ifdef DEBUG
      int frame_count;
  #endif
      int adu_mode; ///< 0 for standard mp3, 1 for adu formatted mp3
      int dither_state;
      int error_recognition;
      AVCodecContext* avctx;
  #if CONFIG_FLOAT
      DCTContext dct;
  #endif
      void (*apply_window_mp3)(MPA_INT *synth_buf, MPA_INT *window,
                               int *dither_state, OUT_INT *samples, int incr);
  } MPADecodeContext;
  
  /* layer 3 huffman tables */
  typedef struct HuffTable {
      int xsize;
      const uint8_t *bits;
      const uint16_t *codes;
  } HuffTable;
  
  int ff_mpa_l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
  int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate);
  extern MPA_INT ff_mpa_synth_window[];
  void ff_mpa_synth_init(MPA_INT *window);
  void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,
                           MPA_INT *window, int *dither_state,
                           OUT_INT *samples, int incr,
                           INTFLOAT sb_samples[SBLIMIT]);
  
  void ff_mpa_synth_init_float(MPA_INT *window);
  void ff_mpa_synth_filter_float(MPADecodeContext *s,
                           MPA_INT *synth_buf_ptr, int *synth_buf_offset,
                           MPA_INT *window, int *dither_state,
                           OUT_INT *samples, int incr,
                           INTFLOAT sb_samples[SBLIMIT]);
  
  void ff_mpegaudiodec_init_mmx(MPADecodeContext *s);
  void ff_mpegaudiodec_init_altivec(MPADecodeContext *s);
  
  /* fast header check for resync */
  static inline int ff_mpa_check_header(uint32_t header){
      /* header */
      if ((header & 0xffe00000) != 0xffe00000)
          return -1;
      /* layer check */
      if ((header & (3<<17)) == 0)
          return -1;
      /* bit rate */
      if ((header & (0xf<<12)) == 0xf<<12)
          return -1;
      /* frequency */
      if ((header & (3<<10)) == 3<<10)
          return -1;
      return 0;
  }
  
  #endif /* AVCODEC_MPEGAUDIO_H */
  