libavcodec/mpeg4audio.c

   1 /*
   2  * MPEG-4 Audio common code
   3  * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
   4  * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "get_bits.h"
  24 #include "put_bits.h"
  25 #include "mpeg4audio.h"
  26
  27 const int ff_mpeg4audio_sample_rates[16] = {
  28     96000, 88200, 64000, 48000, 44100, 32000,
  29     24000, 22050, 16000, 12000, 11025, 8000, 7350
  30 };
  31
  32 const uint8_t ff_mpeg4audio_channels[8] = {
  33     0, 1, 2, 3, 4, 5, 6, 8
  34 };
  35
  36 static inline int get_object_type(GetBitContext *gb)
  37 {
  38     int object_type = get_bits(gb, 5);
  39     if (object_type == 31)
  40         object_type = 32 + get_bits(gb, 6);
  41     return object_type;
  42 }
  43
  44 static inline int get_sample_rate(GetBitContext *gb, int *index)
  45 {
  46     *index = get_bits(gb, 4);
  47     return *index == 0x0f ? get_bits(gb, 24) :
  48         ff_mpeg4audio_sample_rates[*index];
  49 }
  50
  51 int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
  52 {
  53     GetBitContext gb;
  54     int specific_config_bitindex;
  55
  56     init_get_bits(&gb, buf, buf_size*8);
  57     c->object_type = get_object_type(&gb);
  58     c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
  59     c->chan_config = get_bits(&gb, 4);
  60     c->sbr = -1;
  61     if (c->object_type == AOT_SBR) {
  62         c->ext_object_type = c->object_type;
  63         c->sbr = 1;
  64         c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
  65         c->object_type = get_object_type(&gb);
  66         if (c->object_type == AOT_ER_BSAC)
  67             c->ext_chan_config = get_bits(&gb, 4);
  68     } else {
  69         c->ext_object_type = 0;
  70         c->ext_sample_rate = 0;
  71     }
  72     specific_config_bitindex = get_bits_count(&gb);
  73
  74     if (c->ext_object_type != AOT_SBR) {
  75         int bits_left = buf_size*8 - specific_config_bitindex;
  76         for (; bits_left > 15; bits_left--) {
  77             if (show_bits(&gb, 11) == 0x2b7) { // sync extension
  78                 get_bits(&gb, 11);
  79                 c->ext_object_type = get_object_type(&gb);
  80                 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
  81                     c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
  82                 break;
  83             } else
  84                 get_bits1(&gb); // skip 1 bit
  85         }
  86     }
  87     return specific_config_bitindex;
  88 }
  89
  90 static av_always_inline unsigned int copy_bits(PutBitContext *pb,
  91                                                GetBitContext *gb,
  92                                                int bits)
  93 {
  94     unsigned int el = get_bits(gb, bits);
  95     put_bits(pb, bits, el);
  96     return el;
  97 }
  98
  99 int ff_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
 100 {
 101     int five_bit_ch, four_bit_ch, comment_size, bits;
 102     int offset = put_bits_count(pb);
 103
 104     copy_bits(pb, gb, 10);                  //Tag, Object Type, Frequency
 105     five_bit_ch  = copy_bits(pb, gb, 4);    //Front
 106     five_bit_ch += copy_bits(pb, gb, 4);    //Side
 107     five_bit_ch += copy_bits(pb, gb, 4);    //Back
 108     four_bit_ch  = copy_bits(pb, gb, 2);    //LFE
 109     four_bit_ch += copy_bits(pb, gb, 3);    //Data
 110     five_bit_ch += copy_bits(pb, gb, 4);    //Coupling
 111     if (copy_bits(pb, gb, 1))               //Mono Mixdown
 112         copy_bits(pb, gb, 4);
 113     if (copy_bits(pb, gb, 1))               //Stereo Mixdown
 114         copy_bits(pb, gb, 4);
 115     if (copy_bits(pb, gb, 1))               //Matrix Mixdown
 116         copy_bits(pb, gb, 3);
 117     for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
 118         copy_bits(pb, gb, 16);
 119     if (bits)
 120         copy_bits(pb, gb, bits);
 121     align_put_bits(pb);
 122     align_get_bits(gb);
 123     comment_size = copy_bits(pb, gb, 8);
 124     for (; comment_size > 0; comment_size--)
 125         copy_bits(pb, gb, 8);
 126
 127     return put_bits_count(pb) - offset;
 128 }