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