lavc: use avpriv_ prefix for ff_aac_parse_header().
[libav.git] / libavcodec / mpegaudiodecheader.c
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1/*
2 * MPEG Audio header decoder
406792e7 3 * Copyright (c) 2001, 2002 Fabrice Bellard
4bd8e17c 4 *
2912e87a 5 * This file is part of Libav.
4bd8e17c 6 *
2912e87a 7 * Libav is free software; you can redistribute it and/or
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8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
2912e87a 12 * Libav is distributed in the hope that it will be useful,
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13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
2912e87a 18 * License along with Libav; if not, write to the Free Software
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19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
ba87f080 23 * @file
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24 * MPEG Audio header decoder.
25 */
26
27//#define DEBUG
28#include "avcodec.h"
29#include "mpegaudio.h"
30#include "mpegaudiodata.h"
c6e1599b 31#include "mpegaudiodecheader.h"
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32
33
cf92cec7 34int ff_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
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35{
36 int sample_rate, frame_size, mpeg25, padding;
37 int sample_rate_index, bitrate_index;
38 if (header & (1<<20)) {
39 s->lsf = (header & (1<<19)) ? 0 : 1;
40 mpeg25 = 0;
41 } else {
42 s->lsf = 1;
43 mpeg25 = 1;
44 }
45
46 s->layer = 4 - ((header >> 17) & 3);
47 /* extract frequency */
48 sample_rate_index = (header >> 10) & 3;
49 sample_rate = ff_mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);
50 sample_rate_index += 3 * (s->lsf + mpeg25);
51 s->sample_rate_index = sample_rate_index;
52 s->error_protection = ((header >> 16) & 1) ^ 1;
53 s->sample_rate = sample_rate;
54
55 bitrate_index = (header >> 12) & 0xf;
56 padding = (header >> 9) & 1;
57 //extension = (header >> 8) & 1;
58 s->mode = (header >> 6) & 3;
59 s->mode_ext = (header >> 4) & 3;
60 //copyright = (header >> 3) & 1;
61 //original = (header >> 2) & 1;
62 //emphasis = header & 3;
63
64 if (s->mode == MPA_MONO)
65 s->nb_channels = 1;
66 else
67 s->nb_channels = 2;
68
69 if (bitrate_index != 0) {
70 frame_size = ff_mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];
71 s->bit_rate = frame_size * 1000;
72 switch(s->layer) {
73 case 1:
74 frame_size = (frame_size * 12000) / sample_rate;
75 frame_size = (frame_size + padding) * 4;
76 break;
77 case 2:
78 frame_size = (frame_size * 144000) / sample_rate;
79 frame_size += padding;
80 break;
81 default:
82 case 3:
83 frame_size = (frame_size * 144000) / (sample_rate << s->lsf);
84 frame_size += padding;
85 break;
86 }
87 s->frame_size = frame_size;
88 } else {
89 /* if no frame size computed, signal it */
90 return 1;
91 }
92
93#if defined(DEBUG)
dfd2a005 94 av_dlog(NULL, "layer%d, %d Hz, %d kbits/s, ",
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95 s->layer, s->sample_rate, s->bit_rate);
96 if (s->nb_channels == 2) {
97 if (s->layer == 3) {
98 if (s->mode_ext & MODE_EXT_MS_STEREO)
dfd2a005 99 av_dlog(NULL, "ms-");
4bd8e17c 100 if (s->mode_ext & MODE_EXT_I_STEREO)
dfd2a005 101 av_dlog(NULL, "i-");
4bd8e17c 102 }
dfd2a005 103 av_dlog(NULL, "stereo");
4bd8e17c 104 } else {
dfd2a005 105 av_dlog(NULL, "mono");
4bd8e17c 106 }
dfd2a005 107 av_dlog(NULL, "\n");
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108#endif
109 return 0;
110}
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111
112int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate)
113{
114 MPADecodeHeader s1, *s = &s1;
115
116 if (ff_mpa_check_header(head) != 0)
117 return -1;
118
119 if (ff_mpegaudio_decode_header(s, head) != 0) {
120 return -1;
121 }
122
123 switch(s->layer) {
124 case 1:
125 avctx->codec_id = CODEC_ID_MP1;
126 *frame_size = 384;
127 break;
128 case 2:
129 avctx->codec_id = CODEC_ID_MP2;
130 *frame_size = 1152;
131 break;
132 default:
133 case 3:
134 avctx->codec_id = CODEC_ID_MP3;
135 if (s->lsf)
136 *frame_size = 576;
137 else
138 *frame_size = 1152;
139 break;
140 }
141
142 *sample_rate = s->sample_rate;
143 *channels = s->nb_channels;
144 *bit_rate = s->bit_rate;
145 avctx->sub_id = s->layer;
146 return s->frame_size;
147}