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 Libav.
8 * Libav 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 * Libav 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 Libav; 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,
80 int bit_size, int sync_extension)
83 int specific_config_bitindex, ret;
85 ret = init_get_bits(&gb, buf, bit_size);
88 c->object_type = get_object_type(&gb);
89 c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
90 c->chan_config = get_bits(&gb, 4);
91 if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
92 c->channels = ff_mpeg4audio_channels[c->chan_config];
95 if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
96 // check for W6132 Annex YYYY draft MP3onMP4
97 !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
98 if (c->object_type == AOT_PS)
100 c->ext_object_type = AOT_SBR;
102 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
103 c->object_type = get_object_type(&gb);
104 if (c->object_type == AOT_ER_BSAC)
105 c->ext_chan_config = get_bits(&gb, 4);
107 c->ext_object_type = AOT_NULL;
108 c->ext_sample_rate = 0;
110 specific_config_bitindex = get_bits_count(&gb);
112 if (c->object_type == AOT_ALS) {
114 if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
115 skip_bits_long(&gb, 24);
117 specific_config_bitindex = get_bits_count(&gb);
119 if (parse_config_ALS(&gb, c))
123 if (c->ext_object_type != AOT_SBR && sync_extension) {
124 while (get_bits_left(&gb) > 15) {
125 if (show_bits(&gb, 11) == 0x2b7) { // sync extension
127 c->ext_object_type = get_object_type(&gb);
128 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
129 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
130 if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
131 c->ps = get_bits1(&gb);
134 get_bits1(&gb); // skip 1 bit
141 //Limit implicit PS to the HE-AACv2 Profile
142 if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
145 return specific_config_bitindex;
148 static av_always_inline unsigned int copy_bits(PutBitContext *pb,
152 unsigned int el = get_bits(gb, bits);
153 put_bits(pb, bits, el);
157 int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
159 int five_bit_ch, four_bit_ch, comment_size, bits;
160 int offset = put_bits_count(pb);
162 copy_bits(pb, gb, 10); //Tag, Object Type, Frequency
163 five_bit_ch = copy_bits(pb, gb, 4); //Front
164 five_bit_ch += copy_bits(pb, gb, 4); //Side
165 five_bit_ch += copy_bits(pb, gb, 4); //Back
166 four_bit_ch = copy_bits(pb, gb, 2); //LFE
167 four_bit_ch += copy_bits(pb, gb, 3); //Data
168 five_bit_ch += copy_bits(pb, gb, 4); //Coupling
169 if (copy_bits(pb, gb, 1)) //Mono Mixdown
170 copy_bits(pb, gb, 4);
171 if (copy_bits(pb, gb, 1)) //Stereo Mixdown
172 copy_bits(pb, gb, 4);
173 if (copy_bits(pb, gb, 1)) //Matrix Mixdown
174 copy_bits(pb, gb, 3);
175 for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
176 copy_bits(pb, gb, 16);
178 copy_bits(pb, gb, bits);
179 avpriv_align_put_bits(pb);
181 comment_size = copy_bits(pb, gb, 8);
182 for (; comment_size > 0; comment_size--)
183 copy_bits(pb, gb, 8);
185 return put_bits_count(pb) - offset;