FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/mpegaudiodecheader.c
Date: 2026-09-20 08:09:24
Exec Total Coverage
Lines: 87 105 82.9%
Functions: 3 4 75.0%
Branches: 27 32 84.4%
Line Branch Exec Source
1 /*
2 * MPEG Audio header decoder
3 * Copyright (c) 2001, 2002 Fabrice Bellard
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
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 *
12 * FFmpeg is distributed in the hope that it will be useful,
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
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * MPEG Audio header decoder.
25 */
26
27 #include <string.h>
28
29 #include "libavutil/error.h"
30 #include "libavutil/macros.h"
31 #include "libavutil/mem.h"
32
33 #include "mpegaudio.h"
34 #include "mpegaudiodata.h"
35 #include "mpegaudiodecheader.h"
36
37
38 442894340 int ff_mpegaudio_decode_header(MPADecodeHeader2 *s, uint32_t header)
39 {
40 int sample_rate, frame_size, mpeg25, padding;
41 int sample_rate_index, bitrate_index;
42 int ret;
43
44 442894340 ret = ff_mpa_check_header(header);
45
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 442894340 if (ret < 0)
46 442675520 return ret;
47
48 218820 memset(s, 0, sizeof(*s));
49
50
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 218820 if (header & (1<<20)) {
51 192657 s->lsf = (header & (1<<19)) ? 0 : 1;
52 192657 mpeg25 = 0;
53 } else {
54 26163 s->lsf = 1;
55 26163 mpeg25 = 1;
56 }
57
58 218820 s->layer = 4 - ((header >> 17) & 3);
59 /* extract frequency */
60 218820 sample_rate_index = (header >> 10) & 3;
61
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 218820 if (sample_rate_index >= FF_ARRAY_ELEMS(ff_mpa_freq_tab))
62 ✗ sample_rate_index = 0;
63 218820 sample_rate = ff_mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);
64 218820 sample_rate_index += 3 * (s->lsf + mpeg25);
65 218820 s->sample_rate_index = sample_rate_index;
66 218820 s->error_protection = ((header >> 16) & 1) ^ 1;
67 218820 s->sample_rate = sample_rate;
68
69 218820 bitrate_index = (header >> 12) & 0xf;
70 218820 padding = (header >> 9) & 1;
71 218820 s->bitrate_index = bitrate_index;
72 218820 s->padding = padding;
73 218820 s->private_bit = (header >> 8) & 1;
74 218820 s->mode = (header >> 6) & 3;
75 218820 s->mode_ext = (header >> 4) & 3;
76 218820 s->copyright = (header >> 3) & 1;
77 218820 s->original = (header >> 2) & 1;
78 218820 s->emphasis = header & 3;
79
80
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 218820 if (s->mode == MPA_MONO)
81 91715 s->nb_channels = 1;
82 else
83 127105 s->nb_channels = 2;
84
85
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 218820 if (bitrate_index != 0) {
86 114045 frame_size = ff_mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];
87 114045 s->bit_rate = frame_size * 1000;
88
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 114045 switch(s->layer) {
89 47436 case 1:
90 47436 frame_size = (frame_size * 12000) / sample_rate;
91 47436 frame_size = (frame_size + padding) * 4;
92 47436 break;
93 30061 case 2:
94 30061 frame_size = (frame_size * 144000) / sample_rate;
95 30061 frame_size += padding;
96 30061 break;
97 36548 default:
98 case 3:
99 36548 frame_size = (frame_size * 144000) / (sample_rate << s->lsf);
100 36548 frame_size += padding;
101 36548 break;
102 }
103 114045 s->frame_size = frame_size;
104 } else {
105 /* if no frame size computed, signal it */
106 104775 return 1;
107 }
108
109 #if defined(DEBUG)
110 ff_dlog(NULL, "layer%d, %d Hz, %d kbits/s, ",
111 s->layer, s->sample_rate, s->bit_rate);
112 if (s->nb_channels == 2) {
113 if (s->layer == 3) {
114 if (s->mode_ext & MODE_EXT_MS_STEREO)
115 ff_dlog(NULL, "ms-");
116 if (s->mode_ext & MODE_EXT_I_STEREO)
117 ff_dlog(NULL, "i-");
118 }
119 ff_dlog(NULL, "stereo");
120 } else {
121 ff_dlog(NULL, "mono");
122 }
123 ff_dlog(NULL, "\n");
124 #endif
125 114045 return 0;
126 }
127
128 463936559 int avpriv_mpegaudio_decode_header2(MPADecodeHeader2 **phdr, uint32_t header)
129 {
130 463936559 MPADecodeHeader2 *hdr = *phdr;
131 int ret;
132
133
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 463936559 if (!hdr) {
134 21371957 ret = ff_mpa_check_header(header);
135
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 21371957 if (ret < 0)
136 21365741 return ret;
137 6216 hdr = av_mallocz(sizeof(*hdr));
138
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 6216 if (!hdr)
139 ✗ return AVERROR(ENOMEM);
140 }
141
142 442570818 ret = ff_mpegaudio_decode_header(hdr, header);
143
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 442570818 if (ret < 0)
144 442387713 return ret;
145
146 183105 *phdr = hdr;
147 183105 return ret;
148 }
149
150 #if FF_MPEGAUDIO_LEGACY_DECODE_HEADER
151 ✗ int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
152 {
153 ✗ MPADecodeHeader2 hdr = { 0 };
154 ✗ int ret = ff_mpegaudio_decode_header(&hdr, header);
155
156 ✗ if (ret < 0)
157 ✗ return ret;
158
159 /* callers in other libraries allocate the smaller structure, so only
160 its fields may be written */
161 ✗ s->frame_size = hdr.frame_size;
162 ✗ s->error_protection = hdr.error_protection;
163 ✗ s->layer = hdr.layer;
164 ✗ s->sample_rate = hdr.sample_rate;
165 ✗ s->sample_rate_index = hdr.sample_rate_index;
166 ✗ s->bit_rate = hdr.bit_rate;
167 ✗ s->nb_channels = hdr.nb_channels;
168 ✗ s->mode = hdr.mode;
169 ✗ s->mode_ext = hdr.mode_ext;
170 ✗ s->lsf = hdr.lsf;
171
172 ✗ return ret;
173 }
174 #endif
175
176 312380 int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate, enum AVCodecID *codec_id)
177 {
178 312380 MPADecodeHeader2 s1, *s = &s1;
179
180
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 312380 if (ff_mpegaudio_decode_header(s, head) != 0) {
181 287808 return -1;
182 }
183
184
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 24572 switch(s->layer) {
185 68 case 1:
186 68 *codec_id = AV_CODEC_ID_MP1;
187 68 *frame_size = 384;
188 68 break;
189 10898 case 2:
190 10898 *codec_id = AV_CODEC_ID_MP2;
191 10898 *frame_size = 1152;
192 10898 break;
193 13606 default:
194 case 3:
195
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 13606 if (*codec_id != AV_CODEC_ID_MP3ADU)
196 13606 *codec_id = AV_CODEC_ID_MP3;
197
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 13606 if (s->lsf)
198 278 *frame_size = 576;
199 else
200 13328 *frame_size = 1152;
201 13606 break;
202 }
203
204 24572 *sample_rate = s->sample_rate;
205 24572 *channels = s->nb_channels;
206 24572 *bit_rate = s->bit_rate;
207 24572 return s->frame_size;
208 }
209