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 */
parse_config_ALS(GetBitContext * gb,MPEG4AudioConfig * c,void * logctx)33 static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c, void *logctx)
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(logctx, 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 const uint8_t ff_mpeg4audio_channels[14] = {
61 0,
62 1, // mono (1/0)
63 2, // stereo (2/0)
64 3, // 3/0
65 4, // 3/1
66 5, // 3/2
67 6, // 3/2.1
68 8, // 5/2.1
69 0,
70 0,
71 0,
72 7, // 3/3.1
73 8, // 3/2/2.1
74 24 // 3/3/3 - 5/2/3 - 3/0/0.2
75 };
76
get_object_type(GetBitContext * gb)77 static inline int get_object_type(GetBitContext *gb)
78 {
79 int object_type = get_bits(gb, 5);
80 if (object_type == AOT_ESCAPE)
81 object_type = 32 + get_bits(gb, 6);
82 return object_type;
83 }
84
get_sample_rate(GetBitContext * gb,int * index)85 static inline int get_sample_rate(GetBitContext *gb, int *index)
86 {
87 *index = get_bits(gb, 4);
88 return *index == 0x0f ? get_bits(gb, 24) :
89 ff_mpeg4audio_sample_rates[*index];
90 }
91
ff_mpeg4audio_get_config_gb(MPEG4AudioConfig * c,GetBitContext * gb,int sync_extension,void * logctx)92 int ff_mpeg4audio_get_config_gb(MPEG4AudioConfig *c, GetBitContext *gb,
93 int sync_extension, void *logctx)
94 {
95 int specific_config_bitindex, ret;
96 int start_bit_index = get_bits_count(gb);
97 c->object_type = get_object_type(gb);
98 c->sample_rate = get_sample_rate(gb, &c->sampling_index);
99 c->chan_config = get_bits(gb, 4);
100 if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
101 c->channels = ff_mpeg4audio_channels[c->chan_config];
102 else {
103 av_log(logctx, AV_LOG_ERROR, "Invalid chan_config %d\n", c->chan_config);
104 return AVERROR_INVALIDDATA;
105 }
106 c->sbr = -1;
107 c->ps = -1;
108 if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
109 // check for W6132 Annex YYYY draft MP3onMP4
110 !(show_bits(gb, 3) & 0x03 && !(show_bits(gb, 9) & 0x3F)))) {
111 if (c->object_type == AOT_PS)
112 c->ps = 1;
113 c->ext_object_type = AOT_SBR;
114 c->sbr = 1;
115 c->ext_sample_rate = get_sample_rate(gb, &c->ext_sampling_index);
116 c->object_type = get_object_type(gb);
117 if (c->object_type == AOT_ER_BSAC)
118 c->ext_chan_config = get_bits(gb, 4);
119 } else {
120 c->ext_object_type = AOT_NULL;
121 c->ext_sample_rate = 0;
122 }
123 specific_config_bitindex = get_bits_count(gb);
124
125 if (c->object_type == AOT_ALS) {
126 skip_bits(gb, 5);
127 if (show_bits(gb, 24) != MKBETAG('\0','A','L','S'))
128 skip_bits(gb, 24);
129
130 specific_config_bitindex = get_bits_count(gb);
131
132 ret = parse_config_ALS(gb, c, logctx);
133 if (ret < 0)
134 return ret;
135 }
136
137 if (c->ext_object_type != AOT_SBR && sync_extension) {
138 while (get_bits_left(gb) > 15) {
139 if (show_bits(gb, 11) == 0x2b7) { // sync extension
140 get_bits(gb, 11);
141 c->ext_object_type = get_object_type(gb);
142 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(gb)) == 1) {
143 c->ext_sample_rate = get_sample_rate(gb, &c->ext_sampling_index);
144 if (c->ext_sample_rate == c->sample_rate)
145 c->sbr = -1;
146 }
147 if (get_bits_left(gb) > 11 && get_bits(gb, 11) == 0x548)
148 c->ps = get_bits1(gb);
149 break;
150 } else
151 get_bits1(gb); // skip 1 bit
152 }
153 }
154
155 //PS requires SBR
156 if (!c->sbr)
157 c->ps = 0;
158 //Limit implicit PS to the HE-AACv2 Profile
159 if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
160 c->ps = 0;
161
162 return specific_config_bitindex - start_bit_index;
163 }
164
avpriv_mpeg4audio_get_config2(MPEG4AudioConfig * c,const uint8_t * buf,int size,int sync_extension,void * logctx)165 int avpriv_mpeg4audio_get_config2(MPEG4AudioConfig *c, const uint8_t *buf,
166 int size, int sync_extension, void *logctx)
167 {
168 GetBitContext gb;
169 int ret;
170
171 if (size <= 0)
172 return AVERROR_INVALIDDATA;
173
174 ret = init_get_bits8(&gb, buf, size);
175 if (ret < 0)
176 return ret;
177
178 return ff_mpeg4audio_get_config_gb(c, &gb, sync_extension, logctx);
179 }
180