Read extended channel configuration when extended AOT is BSAC.
[libav.git] / libavcodec / mpeg4audio.c
1 /*
2 * MPEG-4 Audio common code
3 * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "get_bits.h"
23 #include "mpeg4audio.h"
24
25 const int ff_mpeg4audio_sample_rates[16] = {
26 96000, 88200, 64000, 48000, 44100, 32000,
27 24000, 22050, 16000, 12000, 11025, 8000, 7350
28 };
29
30 const uint8_t ff_mpeg4audio_channels[8] = {
31 0, 1, 2, 3, 4, 5, 6, 8
32 };
33
34 static inline int get_object_type(GetBitContext *gb)
35 {
36 int object_type = get_bits(gb, 5);
37 if (object_type == 31)
38 object_type = 32 + get_bits(gb, 6);
39 return object_type;
40 }
41
42 static inline int get_sample_rate(GetBitContext *gb, int *index)
43 {
44 *index = get_bits(gb, 4);
45 return *index == 0x0f ? get_bits(gb, 24) :
46 ff_mpeg4audio_sample_rates[*index];
47 }
48
49 int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
50 {
51 GetBitContext gb;
52 int specific_config_bitindex;
53
54 init_get_bits(&gb, buf, buf_size*8);
55 c->object_type = get_object_type(&gb);
56 c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
57 c->chan_config = get_bits(&gb, 4);
58 c->sbr = -1;
59 if (c->object_type == 5) {
60 c->ext_object_type = c->object_type;
61 c->sbr = 1;
62 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
63 c->object_type = get_object_type(&gb);
64 if (c->object_type == AOT_ER_BSAC)
65 c->ext_chan_config = get_bits(&gb, 4);
66 } else {
67 c->ext_object_type = 0;
68 c->ext_sample_rate = 0;
69 }
70 specific_config_bitindex = get_bits_count(&gb);
71
72 if (c->ext_object_type != 5) {
73 int bits_left = buf_size*8 - specific_config_bitindex;
74 for (; bits_left > 15; bits_left--) {
75 if (show_bits(&gb, 11) == 0x2b7) { // sync extension
76 get_bits(&gb, 11);
77 c->ext_object_type = get_object_type(&gb);
78 if (c->ext_object_type == 5 && (c->sbr = get_bits1(&gb)) == 1)
79 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
80 break;
81 } else
82 get_bits1(&gb); // skip 1 bit
83 }
84 }
85 return specific_config_bitindex;
86 }