libavcodec/mpegaudio.h

   1 /*
   2  * copyright (c) 2001 Fabrice Bellard
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file mpegaudio.h
  23  * mpeg audio declarations for both encoder and decoder.
  24  */
  25
  26 #ifndef FFMPEG_MPEGAUDIO_H
  27 #define FFMPEG_MPEGAUDIO_H
  28
  29 #include "avcodec.h"
  30 #include "bitstream.h"
  31 #include "dsputil.h"
  32
  33 /* max frame size, in samples */
  34 #define MPA_FRAME_SIZE 1152
  35
  36 /* max compressed frame size */
  37 #define MPA_MAX_CODED_FRAME_SIZE 1792
  38
  39 #define MPA_MAX_CHANNELS 2
  40
  41 #define SBLIMIT 32 /* number of subbands */
  42
  43 #define MPA_STEREO  0
  44 #define MPA_JSTEREO 1
  45 #define MPA_DUAL    2
  46 #define MPA_MONO    3
  47
  48 /* header + layer + bitrate + freq + lsf/mpeg25 */
  49 #define SAME_HEADER_MASK \
  50    (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))
  51
  52 #define MP3_MASK 0xFFFE0CCF
  53
  54 /* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg
  55    audio decoder */
  56
  57 #ifdef USE_HIGHPRECISION
  58 #define FRAC_BITS   23   /* fractional bits for sb_samples and dct */
  59 #define WFRAC_BITS  16   /* fractional bits for window */
  60 #else
  61 #define FRAC_BITS   15   /* fractional bits for sb_samples and dct */
  62 #define WFRAC_BITS  14   /* fractional bits for window */
  63 #endif
  64
  65 #define FRAC_ONE    (1 << FRAC_BITS)
  66
  67 #define FIX(a)   ((int)((a) * FRAC_ONE))
  68
  69 #if defined(USE_HIGHPRECISION) && defined(CONFIG_AUDIO_NONSHORT)
  70 typedef int32_t OUT_INT;
  71 #define OUT_MAX INT32_MAX
  72 #define OUT_MIN INT32_MIN
  73 #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 31)
  74 #else
  75 typedef int16_t OUT_INT;
  76 #define OUT_MAX INT16_MAX
  77 #define OUT_MIN INT16_MIN
  78 #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)
  79 #endif
  80
  81 #if FRAC_BITS <= 15
  82 typedef int16_t MPA_INT;
  83 #else
  84 typedef int32_t MPA_INT;
  85 #endif
  86
  87 #define BACKSTEP_SIZE 512
  88 #define EXTRABYTES 24
  89
  90 struct GranuleDef;
  91
  92 typedef struct MPADecodeContext {
  93     DECLARE_ALIGNED_8(uint8_t, last_buf[2*BACKSTEP_SIZE + EXTRABYTES]);
  94     int last_buf_size;
  95     int frame_size;
  96     /* next header (used in free format parsing) */
  97     uint32_t free_format_next_header;
  98     int error_protection;
  99     int layer;
 100     int sample_rate;
 101     int sample_rate_index; /* between 0 and 8 */
 102     int bit_rate;
 103     GetBitContext gb;
 104     GetBitContext in_gb;
 105     int nb_channels;
 106     int mode;
 107     int mode_ext;
 108     int lsf;
 109     DECLARE_ALIGNED_16(MPA_INT, synth_buf[MPA_MAX_CHANNELS][512 * 2]);
 110     int synth_buf_offset[MPA_MAX_CHANNELS];
 111     DECLARE_ALIGNED_16(int32_t, sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT]);
 112     int32_t mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */
 113 #ifdef DEBUG
 114     int frame_count;
 115 #endif
 116     void (*compute_antialias)(struct MPADecodeContext *s, struct GranuleDef *g);
 117     int adu_mode; ///< 0 for standard mp3, 1 for adu formatted mp3
 118     int dither_state;
 119     int error_resilience;
 120     AVCodecContext* avctx;
 121 } MPADecodeContext;
 122
 123 /* layer 3 huffman tables */
 124 typedef struct HuffTable {
 125     int xsize;
 126     const uint8_t *bits;
 127     const uint16_t *codes;
 128 } HuffTable;
 129
 130 int ff_mpa_l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
 131 int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate);
 132 void ff_mpa_synth_init(MPA_INT *window);
 133 void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,
 134                          MPA_INT *window, int *dither_state,
 135                          OUT_INT *samples, int incr,
 136                          int32_t sb_samples[SBLIMIT]);
 137
 138 /* fast header check for resync */
 139 static inline int ff_mpa_check_header(uint32_t header){
 140     /* header */
 141     if ((header & 0xffe00000) != 0xffe00000)
 142         return -1;
 143     /* layer check */
 144     if ((header & (3<<17)) == 0)
 145         return -1;
 146     /* bit rate */
 147     if ((header & (0xf<<12)) == 0xf<<12)
 148         return -1;
 149     /* frequency */
 150     if ((header & (3<<10)) == 3<<10)
 151         return -1;
 152     return 0;
 153 }
 154
 155 #endif /* FFMPEG_MPEGAUDIO_H */