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>
6 * This file is part of FFmpeg.
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.
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.
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
25 #include "mpeg4audio.h"
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
33 static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
35 if (get_bits_left(gb) < 112)
38 if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
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);
45 // skip number of samples
46 skip_bits_long(gb, 32);
48 // read number of channels
50 c->channels = get_bits(gb, 16) + 1;
55 const int avpriv_mpeg4audio_sample_rates[16] = {
56 96000, 88200, 64000, 48000, 44100, 32000,
57 24000, 22050, 16000, 12000, 11025, 8000, 7350
60 const uint8_t ff_mpeg4audio_channels[8] = {
61 0, 1, 2, 3, 4, 5, 6, 8
64 static inline int get_object_type(GetBitContext *gb)
66 int object_type = get_bits(gb, 5);
67 if (object_type == AOT_ESCAPE)
68 object_type = 32 + get_bits(gb, 6);
72 static inline int get_sample_rate(GetBitContext *gb, int *index)
74 *index = get_bits(gb, 4);
75 return *index == 0x0f ? get_bits(gb, 24) :
76 avpriv_mpeg4audio_sample_rates[*index];
79 int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
82 int specific_config_bitindex;
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];
92 if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
93 // check for W6132 Annex YYYY draft MP3onMP4
94 !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
95 if (c->object_type == AOT_PS)
97 c->ext_object_type = AOT_SBR;
99 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
100 c->object_type = get_object_type(&gb);
101 if (c->object_type == AOT_ER_BSAC)
102 c->ext_chan_config = get_bits(&gb, 4);
104 c->ext_object_type = AOT_NULL;
105 c->ext_sample_rate = 0;
107 specific_config_bitindex = get_bits_count(&gb);
109 if (c->object_type == AOT_ALS) {
111 if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
112 skip_bits_long(&gb, 24);
114 specific_config_bitindex = get_bits_count(&gb);
116 if (parse_config_ALS(&gb, c))
120 if (c->ext_object_type != AOT_SBR) {
121 while (get_bits_left(&gb) > 15) {
122 if (show_bits(&gb, 11) == 0x2b7) { // sync extension
124 c->ext_object_type = get_object_type(&gb);
125 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
126 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
127 if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
128 c->ps = get_bits1(&gb);
131 get_bits1(&gb); // skip 1 bit
138 //Limit implicit PS to the HE-AACv2 Profile
139 if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
142 return specific_config_bitindex;
145 static av_always_inline unsigned int copy_bits(PutBitContext *pb,
149 unsigned int el = get_bits(gb, bits);
150 put_bits(pb, bits, el);
154 int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
156 int five_bit_ch, four_bit_ch, comment_size, bits;
157 int offset = put_bits_count(pb);
159 copy_bits(pb, gb, 10); //Tag, Object Type, Frequency
160 five_bit_ch = copy_bits(pb, gb, 4); //Front
161 five_bit_ch += copy_bits(pb, gb, 4); //Side
162 five_bit_ch += copy_bits(pb, gb, 4); //Back
163 four_bit_ch = copy_bits(pb, gb, 2); //LFE
164 four_bit_ch += copy_bits(pb, gb, 3); //Data
165 five_bit_ch += copy_bits(pb, gb, 4); //Coupling
166 if (copy_bits(pb, gb, 1)) //Mono Mixdown
167 copy_bits(pb, gb, 4);
168 if (copy_bits(pb, gb, 1)) //Stereo Mixdown
169 copy_bits(pb, gb, 4);
170 if (copy_bits(pb, gb, 1)) //Matrix Mixdown
171 copy_bits(pb, gb, 3);
172 for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
173 copy_bits(pb, gb, 16);
175 copy_bits(pb, gb, bits);
176 avpriv_align_put_bits(pb);
178 comment_size = copy_bits(pb, gb, 8);
179 for (; comment_size > 0; comment_size--)
180 copy_bits(pb, gb, 8);
182 return put_bits_count(pb) - offset;