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 /**
  28  * Parse MPEG-4 audio configuration for ALS object type.
  29  * @param[in] gb       bit reader context
  30  * @param[in] c        MPEG4AudioConfig structure to fill
  31  * @return on success 0 is returned, otherwise a value < 0
  32  */
  33 static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
  34 {
  35     if (get_bits_left(gb) < 112)
  36         return -1;
  37
  38     if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
  39         return -1;
  40
  41     // override AudioSpecificConfig channel configuration and sample rate
  42     // which are buggy in old ALS conformance files
  43     c->sample_rate = get_bits_long(gb, 32);
  44
  45     // skip number of samples
  46     skip_bits_long(gb, 32);
  47
  48     // read number of channels
  49     c->chan_config = 0;
  50     c->channels    = get_bits(gb, 16) + 1;
  51
  52     return 0;
  53 }
  54
  55 const int ff_mpeg4audio_sample_rates[16] = {
  56     96000, 88200, 64000, 48000, 44100, 32000,
  57     24000, 22050, 16000, 12000, 11025, 8000, 7350
  58 };
  59
  60 const uint8_t ff_mpeg4audio_channels[8] = {
  61     0, 1, 2, 3, 4, 5, 6, 8
  62 };
  63
  64 static inline int get_object_type(GetBitContext *gb)
  65 {
  66     int object_type = get_bits(gb, 5);
  67     if (object_type == AOT_ESCAPE)
  68         object_type = 32 + get_bits(gb, 6);
  69     return object_type;
  70 }
  71
  72 static inline int get_sample_rate(GetBitContext *gb, int *index)
  73 {
  74     *index = get_bits(gb, 4);
  75     return *index == 0x0f ? get_bits(gb, 24) :
  76         ff_mpeg4audio_sample_rates[*index];
  77 }
  78
  79 int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
  80 {
  81     GetBitContext gb;
  82     int specific_config_bitindex;
  83
  84     init_get_bits(&gb, buf, buf_size*8);
  85     c->object_type = get_object_type(&gb);
  86     c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
  87     c->chan_config = get_bits(&gb, 4);
  88     if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
  89         c->channels = ff_mpeg4audio_channels[c->chan_config];
  90     c->sbr = -1;
  91     if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
  92         // check for W6132 Annex YYYY draft MP3onMP4
  93         !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
  94         c->ext_object_type = c->object_type;
  95         c->sbr = 1;
  96         c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
  97         c->object_type = get_object_type(&gb);
  98         if (c->object_type == AOT_ER_BSAC)
  99             c->ext_chan_config = get_bits(&gb, 4);
 100     } else {
 101         c->ext_object_type = AOT_NULL;
 102         c->ext_sample_rate = 0;
 103     }
 104     specific_config_bitindex = get_bits_count(&gb);
 105
 106     if (c->object_type == AOT_ALS) {
 107         skip_bits(&gb, 5);
 108         if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
 109             skip_bits_long(&gb, 24);
 110
 111         specific_config_bitindex = get_bits_count(&gb);
 112
 113         if (parse_config_ALS(&gb, c))
 114             return -1;
 115     }
 116
 117     if (c->ext_object_type != AOT_SBR) {
 118         int bits_left = buf_size*8 - get_bits_count(&gb);
 119         for (; bits_left > 15; bits_left--) {
 120             if (show_bits(&gb, 11) == 0x2b7) { // sync extension
 121                 get_bits(&gb, 11);
 122                 c->ext_object_type = get_object_type(&gb);
 123                 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
 124                     c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
 125                 break;
 126             } else
 127                 get_bits1(&gb); // skip 1 bit
 128         }
 129     }
 130     return specific_config_bitindex;
 131 }
 132
 133 static av_always_inline unsigned int copy_bits(PutBitContext *pb,
 134                                                GetBitContext *gb,
 135                                                int bits)
 136 {
 137     unsigned int el = get_bits(gb, bits);
 138     put_bits(pb, bits, el);
 139     return el;
 140 }
 141
 142 int ff_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
 143 {
 144     int five_bit_ch, four_bit_ch, comment_size, bits;
 145     int offset = put_bits_count(pb);
 146
 147     copy_bits(pb, gb, 10);                  //Tag, Object Type, Frequency
 148     five_bit_ch  = copy_bits(pb, gb, 4);    //Front
 149     five_bit_ch += copy_bits(pb, gb, 4);    //Side
 150     five_bit_ch += copy_bits(pb, gb, 4);    //Back
 151     four_bit_ch  = copy_bits(pb, gb, 2);    //LFE
 152     four_bit_ch += copy_bits(pb, gb, 3);    //Data
 153     five_bit_ch += copy_bits(pb, gb, 4);    //Coupling
 154     if (copy_bits(pb, gb, 1))               //Mono Mixdown
 155         copy_bits(pb, gb, 4);
 156     if (copy_bits(pb, gb, 1))               //Stereo Mixdown
 157         copy_bits(pb, gb, 4);
 158     if (copy_bits(pb, gb, 1))               //Matrix Mixdown
 159         copy_bits(pb, gb, 3);
 160     for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
 161         copy_bits(pb, gb, 16);
 162     if (bits)
 163         copy_bits(pb, gb, bits);
 164     align_put_bits(pb);
 165     align_get_bits(gb);
 166     comment_size = copy_bits(pb, gb, 8);
 167     for (; comment_size > 0; comment_size--)
 168         copy_bits(pb, gb, 8);
 169
 170     return put_bits_count(pb) - offset;
 171 }