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path: root/libavcodec/mpeg4audio.c (plain)
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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 */
33static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
34{
35 if (get_bits_left(gb) < 112)
36 return AVERROR_INVALIDDATA;
37
38 if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
39 return AVERROR_INVALIDDATA;
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 if (c->sample_rate <= 0) {
46 av_log(NULL, AV_LOG_ERROR, "Invalid sample rate %d\n", c->sample_rate);
47 return AVERROR_INVALIDDATA;
48 }
49
50 // skip number of samples
51 skip_bits_long(gb, 32);
52
53 // read number of channels
54 c->chan_config = 0;
55 c->channels = get_bits(gb, 16) + 1;
56
57 return 0;
58}
59
60/* XXX: make sure to update the copies in the different encoders if you change
61 * this table */
62const int avpriv_mpeg4audio_sample_rates[16] = {
63 96000, 88200, 64000, 48000, 44100, 32000,
64 24000, 22050, 16000, 12000, 11025, 8000, 7350
65};
66
67const uint8_t ff_mpeg4audio_channels[8] = {
68 0, 1, 2, 3, 4, 5, 6, 8
69};
70
71static inline int get_object_type(GetBitContext *gb)
72{
73 int object_type = get_bits(gb, 5);
74 if (object_type == AOT_ESCAPE)
75 object_type = 32 + get_bits(gb, 6);
76 return object_type;
77}
78
79static inline int get_sample_rate(GetBitContext *gb, int *index)
80{
81 *index = get_bits(gb, 4);
82 return *index == 0x0f ? get_bits(gb, 24) :
83 avpriv_mpeg4audio_sample_rates[*index];
84}
85
86int ff_mpeg4audio_get_config_gb(MPEG4AudioConfig *c, GetBitContext *gb,
87 int sync_extension)
88{
89 int specific_config_bitindex, ret;
90 int start_bit_index = get_bits_count(gb);
91 c->object_type = get_object_type(gb);
92 c->sample_rate = get_sample_rate(gb, &c->sampling_index);
93 c->chan_config = get_bits(gb, 4);
94 if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
95 c->channels = ff_mpeg4audio_channels[c->chan_config];
96 c->sbr = -1;
97 c->ps = -1;
98 if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
99 // check for W6132 Annex YYYY draft MP3onMP4
100 !(show_bits(gb, 3) & 0x03 && !(show_bits(gb, 9) & 0x3F)))) {
101 if (c->object_type == AOT_PS)
102 c->ps = 1;
103 c->ext_object_type = AOT_SBR;
104 c->sbr = 1;
105 c->ext_sample_rate = get_sample_rate(gb, &c->ext_sampling_index);
106 c->object_type = get_object_type(gb);
107 if (c->object_type == AOT_ER_BSAC)
108 c->ext_chan_config = get_bits(gb, 4);
109 } else {
110 c->ext_object_type = AOT_NULL;
111 c->ext_sample_rate = 0;
112 }
113 specific_config_bitindex = get_bits_count(gb);
114
115 if (c->object_type == AOT_ALS) {
116 skip_bits(gb, 5);
117 if (show_bits_long(gb, 24) != MKBETAG('\0','A','L','S'))
118 skip_bits_long(gb, 24);
119
120 specific_config_bitindex = get_bits_count(gb);
121
122 ret = parse_config_ALS(gb, c);
123 if (ret < 0)
124 return ret;
125 }
126
127 if (c->ext_object_type != AOT_SBR && sync_extension) {
128 while (get_bits_left(gb) > 15) {
129 if (show_bits(gb, 11) == 0x2b7) { // sync extension
130 get_bits(gb, 11);
131 c->ext_object_type = get_object_type(gb);
132 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(gb)) == 1) {
133 c->ext_sample_rate = get_sample_rate(gb, &c->ext_sampling_index);
134 if (c->ext_sample_rate == c->sample_rate)
135 c->sbr = -1;
136 }
137 if (get_bits_left(gb) > 11 && get_bits(gb, 11) == 0x548)
138 c->ps = get_bits1(gb);
139 break;
140 } else
141 get_bits1(gb); // skip 1 bit
142 }
143 }
144
145 //PS requires SBR
146 if (!c->sbr)
147 c->ps = 0;
148 //Limit implicit PS to the HE-AACv2 Profile
149 if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
150 c->ps = 0;
151
152 return specific_config_bitindex - start_bit_index;
153}
154
155int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf,
156 int bit_size, int sync_extension)
157{
158 GetBitContext gb;
159 int ret;
160
161 if (bit_size <= 0)
162 return AVERROR_INVALIDDATA;
163
164 ret = init_get_bits(&gb, buf, bit_size);
165 if (ret < 0)
166 return ret;
167
168 return ff_mpeg4audio_get_config_gb(c, &gb, sync_extension);
169}
170
171static av_always_inline unsigned int copy_bits(PutBitContext *pb,
172 GetBitContext *gb,
173 int bits)
174{
175 unsigned int el = get_bits(gb, bits);
176 put_bits(pb, bits, el);
177 return el;
178}
179
180int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
181{
182 int five_bit_ch, four_bit_ch, comment_size, bits;
183 int offset = put_bits_count(pb);
184
185 copy_bits(pb, gb, 10); //Tag, Object Type, Frequency
186 five_bit_ch = copy_bits(pb, gb, 4); //Front
187 five_bit_ch += copy_bits(pb, gb, 4); //Side
188 five_bit_ch += copy_bits(pb, gb, 4); //Back
189 four_bit_ch = copy_bits(pb, gb, 2); //LFE
190 four_bit_ch += copy_bits(pb, gb, 3); //Data
191 five_bit_ch += copy_bits(pb, gb, 4); //Coupling
192 if (copy_bits(pb, gb, 1)) //Mono Mixdown
193 copy_bits(pb, gb, 4);
194 if (copy_bits(pb, gb, 1)) //Stereo Mixdown
195 copy_bits(pb, gb, 4);
196 if (copy_bits(pb, gb, 1)) //Matrix Mixdown
197 copy_bits(pb, gb, 3);
198 for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
199 copy_bits(pb, gb, 16);
200 if (bits)
201 copy_bits(pb, gb, bits);
202 avpriv_align_put_bits(pb);
203 align_get_bits(gb);
204 comment_size = copy_bits(pb, gb, 8);
205 for (; comment_size > 0; comment_size--)
206 copy_bits(pb, gb, 8);
207
208 return put_bits_count(pb) - offset;
209}
210
generated by cgit at 2024-05-17 01:48:47 (GMT)