FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavformat/mp3dec.c
Date: 2026-04-19 20:43:40
Exec Total Coverage
Lines: 272 310 87.7%
Functions: 10 10 100.0%
Branches: 174 240 72.5%
Line Branch Exec Source
1 /*
2 * MP3 demuxer
3 * Copyright (c) 2003 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 #include "libavutil/opt.h"
23 #include "libavutil/intreadwrite.h"
24 #include "libavutil/dict.h"
25 #include "libavutil/mathematics.h"
26 #include "avformat.h"
27 #include "internal.h"
28 #include "avio_internal.h"
29 #include "demux.h"
30 #include "id3v2.h"
31 #include "id3v1.h"
32 #include "replaygain.h"
33
34 #include "libavcodec/codec_id.h"
35 #include "libavcodec/mpegaudio.h"
36 #include "libavcodec/mpegaudiodecheader.h"
37
38 #define XING_FLAG_FRAMES 0x01
39 #define XING_FLAG_SIZE 0x02
40 #define XING_FLAG_TOC 0x04
41 #define XING_FLAC_QSCALE 0x08
42
43 #define XING_TOC_COUNT 100
44
45
46 typedef struct {
47 AVClass *class;
48 int64_t filesize;
49 int xing_toc;
50 int start_pad;
51 int end_pad;
52 int usetoc;
53 unsigned frames; /* Total number of frames in file */
54 unsigned header_filesize; /* Total number of bytes in the stream */
55 unsigned frame_duration; /* Frame duration in st->time_base */
56 int is_cbr;
57 } MP3DecContext;
58
59 enum CheckRet {
60 CHECK_WRONG_HEADER = -1,
61 CHECK_SEEK_FAILED = -2,
62 };
63
64 static int check(AVIOContext *pb, int64_t pos, uint32_t *header);
65
66 /* mp3 read */
67
68 7467 static int mp3_read_probe(const AVProbeData *p)
69 {
70 7467 int max_frames, first_frames = 0;
71 7467 int whole_used = 0;
72 int frames, ret;
73 int framesizes, max_framesizes;
74 uint32_t header;
75 const uint8_t *buf, *buf0, *buf2, *buf3, *end;
76
77 7467 buf0 = p->buf;
78 7467 end = p->buf + p->buf_size - sizeof(uint32_t);
79
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 118606 while (buf0 < end && !*buf0)
80 111139 buf0++;
81
82 7467 max_frames = 0;
83 7467 max_framesizes = 0;
84 7467 buf = buf0;
85
86
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 389645037 for (; buf < end; buf = buf2+1) {
87 389637570 buf2 = buf;
88
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 389707328 for (framesizes = frames = 0; buf2 < end; frames++) {
89 MPADecodeHeader h;
90 389707327 int header_emu = 0;
91 int available;
92
93 389707327 header = AV_RB32(buf2);
94 389707327 ret = avpriv_mpegaudio_decode_header(&h, header);
95
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 389707327 if (ret != 0)
96 389637569 break;
97
98 71924 available = FFMIN(h.frame_size, end - buf2);
99
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 28279475 for (buf3 = buf2 + 4; buf3 < buf2 + available; buf3++) {
100 28207551 uint32_t next_sync = AV_RB32(buf3);
101 28207551 header_emu += (next_sync & MP3_MASK) == (header & MP3_MASK);
102 }
103
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 71924 if (header_emu > 2)
104 1160 break;
105 70764 framesizes += h.frame_size;
106
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 70764 if (available < h.frame_size) {
107 1006 frames++;
108 1006 break;
109 }
110 69758 buf2 += h.frame_size;
111 }
112 389637570 max_frames = FFMAX(max_frames, frames);
113 389637570 max_framesizes = FFMAX(max_framesizes, framesizes);
114
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 389637570 if (buf == buf0) {
115 7467 first_frames= frames;
116
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 7467 if (buf2 == end + sizeof(uint32_t))
117 ✗ whole_used = 1;
118 }
119 }
120 // keep this in sync with ac3 probe, both need to avoid
121 // issues with MPEG-files!
122
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 7467 if (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;
123
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 7438 else if (max_frames>200 && p->buf_size < 2*max_framesizes)return AVPROBE_SCORE_EXTENSION;
124
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 7437 else if (max_frames>=4 && p->buf_size < 2*max_framesizes) return AVPROBE_SCORE_EXTENSION / 2;
125
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 7427 else if (ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
126
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 22 return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2;
127
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 7405 else if (first_frames > 1 && whole_used) return 5;
128
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 7405 else if (max_frames>=1 && p->buf_size < 10*max_framesizes) return 1;
129 6165 else return 0;
130 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
131 }
132
133 17 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
134 {
135 int i;
136 17 MP3DecContext *mp3 = s->priv_data;
137 17 int fast_seek = s->flags & AVFMT_FLAG_FAST_SEEK;
138
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 17 int fill_index = (mp3->usetoc || fast_seek) && duration > 0;
139
140
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 17 if (!filesize &&
141 ✗ (filesize = avio_size(s->pb)) <= 0) {
142 ✗ av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
143 ✗ fill_index = 0;
144 ✗ filesize = 0;
145 }
146
147
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 1717 for (i = 0; i < XING_TOC_COUNT; i++) {
148 1700 uint8_t b = avio_r8(s->pb);
149
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 1700 if (fill_index)
150 100 av_add_index_entry(s->streams[0],
151 av_rescale(b, filesize, 256),
152 av_rescale(i, duration, XING_TOC_COUNT),
153 0, 0, AVINDEX_KEYFRAME);
154 }
155
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 17 if (fill_index)
156 1 mp3->xing_toc = 1;
157 17 }
158
159 28 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
160 MPADecodeHeader *c, uint32_t spf)
161 {
162 #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
163 #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m) + 1))
164
165 28 FFStream *const sti = ffstream(st);
166 uint16_t crc;
167 uint32_t v;
168
169 char version[10];
170
171 28 uint32_t peak = 0;
172 28 int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
173
174 28 MP3DecContext *mp3 = s->priv_data;
175 static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
176 28 uint64_t fsize = avio_size(s->pb);
177 28 int64_t pos = avio_tell(s->pb);
178
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 28 fsize = fsize >= pos ? fsize - pos : 0;
179
180 /* Check for Xing / Info tag */
181 28 avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
182 28 v = avio_rb32(s->pb);
183 28 mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
184
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 28 if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
185 10 return;
186
187 18 v = avio_rb32(s->pb);
188
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 18 if (v & XING_FLAG_FRAMES)
189 18 mp3->frames = avio_rb32(s->pb);
190
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 18 if (v & XING_FLAG_SIZE)
191 17 mp3->header_filesize = avio_rb32(s->pb);
192
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 18 if (fsize && mp3->header_filesize) {
193 uint64_t min, delta;
194 17 min = FFMIN(fsize, mp3->header_filesize);
195 17 delta = FFMAX(fsize, mp3->header_filesize) - min;
196
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 17 if (fsize > mp3->header_filesize && delta > min >> 4) {
197 ✗ mp3->frames = 0;
198 ✗ av_log(s, AV_LOG_WARNING,
199 "invalid concatenated file detected - using bitrate for duration\n");
200
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 17 } else if (delta > min >> 4) {
201 ✗ av_log(s, AV_LOG_WARNING,
202 "filesize and duration do not match (growing file?)\n");
203 }
204 }
205
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 18 if (v & XING_FLAG_TOC)
206 17 read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
207 17 (AVRational){spf, c->sample_rate},
208 st->time_base));
209 /* VBR quality */
210
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 18 if (v & XING_FLAC_QSCALE)
211 15 avio_rb32(s->pb);
212
213 /* Encoder short version string */
214 18 memset(version, 0, sizeof(version));
215 18 avio_read(s->pb, version, 9);
216
217 /* Info Tag revision + VBR method */
218 18 avio_r8(s->pb);
219
220 /* Lowpass filter value */
221 18 avio_r8(s->pb);
222
223 /* ReplayGain peak */
224 18 v = avio_rb32(s->pb);
225 18 peak = av_rescale(v, 100000, 1 << 23);
226
227 /* Radio ReplayGain */
228 18 v = avio_rb16(s->pb);
229
230
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 18 if (MIDDLE_BITS(v, 13, 15) == 1) {
231 ✗ r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
232
233 ✗ if (v & (1 << 9))
234 ✗ r_gain *= -1;
235 }
236
237 /* Audiophile ReplayGain */
238 18 v = avio_rb16(s->pb);
239
240
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 18 if (MIDDLE_BITS(v, 13, 15) == 2) {
241 ✗ a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
242
243 ✗ if (v & (1 << 9))
244 ✗ a_gain *= -1;
245 }
246
247 /* Encoding flags + ATH Type */
248 18 avio_r8(s->pb);
249
250 /* if ABR {specified bitrate} else {minimal bitrate} */
251 18 avio_r8(s->pb);
252
253 /* Encoder delays */
254 18 v = avio_rb24(s->pb);
255
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 18 if (AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E')
256
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 8 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f')
257
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 1 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'c')
258 ) {
259
260 17 mp3->start_pad = v>>12;
261 17 mp3-> end_pad = v&4095;
262 17 sti->start_skip_samples = mp3->start_pad + 528 + 1;
263
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 17 if (mp3->frames) {
264 17 sti->first_discard_sample = -mp3->end_pad + 528 + 1 + mp3->frames * (int64_t)spf;
265 17 sti->last_discard_sample = mp3->frames * (int64_t)spf;
266 }
267
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 17 if (!st->start_time)
268 17 st->start_time = av_rescale_q(sti->start_skip_samples,
269 17 (AVRational){1, c->sample_rate},
270 st->time_base);
271 17 av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
272 }
273
274 /* Misc */
275 18 avio_r8(s->pb);
276
277 /* MP3 gain */
278 18 avio_r8(s->pb);
279
280 /* Preset and surround info */
281 18 avio_rb16(s->pb);
282
283 /* Music length */
284 18 avio_rb32(s->pb);
285
286 /* Music CRC */
287 18 avio_rb16(s->pb);
288
289 /* Info Tag CRC */
290 18 crc = ffio_get_checksum(s->pb);
291 18 v = avio_rb16(s->pb);
292
293
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 18 if (v == crc) {
294 12 ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
295 12 av_dict_set(&st->metadata, "encoder", version, 0);
296 }
297 }
298
299 28 static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
300 {
301 uint32_t v;
302 28 MP3DecContext *mp3 = s->priv_data;
303
304 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
305 28 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
306 28 v = avio_rb32(s->pb);
307
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 28 if (v == MKBETAG('V', 'B', 'R', 'I')) {
308 /* Check tag version */
309 ✗ if (avio_rb16(s->pb) == 1) {
310 /* skip delay and quality */
311 ✗ avio_skip(s->pb, 4);
312 ✗ mp3->header_filesize = avio_rb32(s->pb);
313 ✗ mp3->frames = avio_rb32(s->pb);
314 }
315 }
316 28 }
317
318 /**
319 * Try to find Xing/Info/VBRI tags and compute duration from info therein
320 */
321 33 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
322 {
323 uint32_t v, spf;
324 MPADecodeHeader c;
325 33 int vbrtag_size = 0;
326 33 MP3DecContext *mp3 = s->priv_data;
327 int ret;
328
329 33 ffio_init_checksum(s->pb, ff_crcA001_update, 0);
330
331 33 v = avio_rb32(s->pb);
332
333 33 ret = avpriv_mpegaudio_decode_header(&c, v);
334
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 33 if (ret < 0)
335 2 return ret;
336
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 31 else if (ret == 0)
337 31 vbrtag_size = c.frame_size;
338
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 31 if (c.layer != 3)
339 3 return -1;
340
341
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 28 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
342
343 28 mp3->frames = 0;
344 28 mp3->header_filesize = 0;
345 28 mp3->frame_duration = av_rescale_q(spf, (AVRational){1, c.sample_rate}, st->time_base);
346
347 28 mp3_parse_info_tag(s, st, &c, spf);
348 28 mp3_parse_vbri_tag(s, st, base);
349
350
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 28 if (!mp3->frames && !mp3->header_filesize)
351 10 return -1;
352
353 /* Skip the vbr tag frame */
354 18 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
355
356
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 18 if (mp3->frames) {
357 int64_t full_duration_samples;
358
359 18 full_duration_samples = mp3->frames * (int64_t)spf;
360 18 st->duration = av_rescale_q(full_duration_samples - mp3->start_pad - mp3->end_pad,
361 18 (AVRational){1, c.sample_rate},
362 st->time_base);
363
364
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 18 if (mp3->header_filesize && !mp3->is_cbr)
365 1 st->codecpar->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate,
366 full_duration_samples);
367 }
368
369 18 return 0;
370 }
371
372 33 static int mp3_read_header(AVFormatContext *s)
373 {
374 33 FFFormatContext *const si = ffformatcontext(s);
375 33 MP3DecContext *mp3 = s->priv_data;
376 AVStream *st;
377 FFStream *sti;
378 int64_t off;
379 int ret;
380 int i;
381
382 33 s->metadata = si->id3v2_meta;
383 33 si->id3v2_meta = NULL;
384
385 33 st = avformat_new_stream(s, NULL);
386
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 33 if (!st)
387 ✗ return AVERROR(ENOMEM);
388 33 sti = ffstream(st);
389
390 33 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
391 33 st->codecpar->codec_id = AV_CODEC_ID_MP3;
392 33 sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
393 33 st->start_time = 0;
394
395 // lcm of all mp3 sample rates
396 33 avpriv_set_pts_info(st, 64, 1, 14112000);
397
398 33 ffiocontext(s->pb)->maxsize = -1;
399 33 off = avio_tell(s->pb);
400
401
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 33 if (!av_dict_count(s->metadata))
402 14 ff_id3v1_read(s);
403
404
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 33 if (s->pb->seekable & AVIO_SEEKABLE_NORMAL)
405 33 mp3->filesize = avio_size(s->pb);
406
407
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 33 if (mp3_parse_vbr_tags(s, st, off) < 0)
408 15 avio_seek(s->pb, off, SEEK_SET);
409
410 33 ret = ff_replaygain_export(st, s->metadata);
411
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 33 if (ret < 0)
412 ✗ return ret;
413
414 33 ret = ffio_ensure_seekback(s->pb, 64 * 1024 + MPA_MAX_CODED_FRAME_SIZE + 4);
415
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 33 if (ret < 0)
416 ✗ return ret;
417
418 33 off = avio_tell(s->pb);
419
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 659 for (i = 0; i < 64 * 1024; i++) {
420 uint32_t header, header2;
421 int frame_size;
422 659 frame_size = check(s->pb, off + i, &header);
423
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 659 if (frame_size > 0) {
424 32 ret = check(s->pb, off + i + frame_size, &header2);
425
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 32 if (ret >= 0 && (header & MP3_MASK) == (header2 & MP3_MASK))
426 32 break;
427
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 627 } else if (frame_size == CHECK_SEEK_FAILED) {
428 1 av_log(s, AV_LOG_ERROR, "Failed to find two consecutive MPEG audio frames.\n");
429 1 return AVERROR_INVALIDDATA;
430 }
431 }
432
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 32 if (i == 64 * 1024) {
433 ✗ off = avio_seek(s->pb, off, SEEK_SET);
434 } else {
435
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 32 av_log(s, i > 0 ? AV_LOG_INFO : AV_LOG_VERBOSE, "Skipping %d bytes of junk at %"PRId64".\n", i, off);
436 32 off = avio_seek(s->pb, off + i, SEEK_SET);
437 }
438
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 32 if (off < 0)
439 ✗ return off;
440
441 // the seek index is relative to the end of the xing vbr headers
442
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 132 for (int i = 0; i < sti->nb_index_entries; i++)
443 100 sti->index_entries[i].pos += off;
444
445 /* the parameters will be extracted from the compressed bitstream */
446 32 return 0;
447 }
448
449 #define MP3_PACKET_SIZE 1024
450
451 3141 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
452 {
453 3141 MP3DecContext *mp3 = s->priv_data;
454 int ret, size;
455 int64_t pos;
456
457 3141 size = MP3_PACKET_SIZE;
458 3141 pos = avio_tell(s->pb);
459
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 3141 if (mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
460 3105 size= FFMIN(size, mp3->filesize - pos);
461
462 3141 ret = av_get_packet(s->pb, pkt, size);
463
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 3141 if (ret <= 0) {
464
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 36 if(ret<0)
465 36 return ret;
466 ✗ return AVERROR_EOF;
467 }
468
469 3105 pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
470 3105 pkt->stream_index = 0;
471
472 3105 return ret;
473 }
474
475 #define SEEK_WINDOW 4096
476
477 17727 static int check(AVIOContext *pb, int64_t pos, uint32_t *ret_header)
478 {
479 17727 int64_t ret = avio_seek(pb, pos, SEEK_SET);
480 uint8_t header_buf[4];
481 unsigned header;
482 MPADecodeHeader sd;
483
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 17727 if (ret < 0)
484 ✗ return CHECK_SEEK_FAILED;
485
486 17727 ret = avio_read(pb, &header_buf[0], 4);
487 /* We should always find four bytes for a valid mpa header. */
488
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 17727 if (ret < 4)
489 1 return CHECK_SEEK_FAILED;
490
491 17726 header = AV_RB32(&header_buf[0]);
492
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 17726 if (ff_mpa_check_header(header) < 0)
493 17490 return CHECK_WRONG_HEADER;
494
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 236 if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
495 ✗ return CHECK_WRONG_HEADER;
496
497
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 236 if (ret_header)
498 64 *ret_header = header;
499 236 return sd.frame_size;
500 }
501
502 26 static int64_t mp3_sync(AVFormatContext *s, int64_t target_pos, int flags)
503 {
504
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 26 int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
505 int64_t best_pos;
506 int best_score, i, j;
507 int64_t ret;
508
509 26 avio_seek(s->pb, FFMAX(target_pos - SEEK_WINDOW, 0), SEEK_SET);
510 26 ret = avio_seek(s->pb, target_pos, SEEK_SET);
511
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 26 if (ret < 0)
512 ✗ return ret;
513
514 #define MIN_VALID 3
515 26 best_pos = target_pos;
516 26 best_score = 999;
517
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 16916 for (i = 0; i < SEEK_WINDOW; i++) {
518
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 16916 int64_t pos = target_pos + (dir > 0 ? i - SEEK_WINDOW/4 : -i);
519 16916 int64_t candidate = -1;
520 16916 int score = 999;
521
522
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 16916 if (pos < 0)
523 ✗ continue;
524
525
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 17088 for (j = 0; j < MIN_VALID; j++) {
526 17036 ret = check(s->pb, pos, NULL);
527
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 17036 if (ret < 0) {
528
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 16864 if (ret == CHECK_WRONG_HEADER) {
529 16864 break;
530 ✗ } else if (ret == CHECK_SEEK_FAILED) {
531 ✗ av_log(s, AV_LOG_ERROR, "Could not seek to %"PRId64".\n", pos);
532 ✗ return AVERROR(EINVAL);
533 }
534 }
535
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 172 if ((target_pos - pos)*dir <= 0 && FFABS(MIN_VALID/2-j) < score) {
536 68 candidate = pos;
537
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 68 score = FFABS(MIN_VALID/2-j);
538 }
539 172 pos += ret;
540 }
541
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 16916 if (best_score > score && j == MIN_VALID) {
542 48 best_pos = candidate;
543 48 best_score = score;
544
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 48 if(score == 0)
545 26 break;
546 }
547 }
548
549 26 return avio_seek(s->pb, best_pos, SEEK_SET);
550 }
551
552 128 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
553 int flags)
554 {
555 128 FFFormatContext *const si = ffformatcontext(s);
556 128 MP3DecContext *mp3 = s->priv_data;
557 AVIndexEntry *ie, ie1;
558 128 AVStream *st = s->streams[0];
559 128 FFStream *const sti = ffstream(st);
560 int64_t best_pos;
561 128 int fast_seek = s->flags & AVFMT_FLAG_FAST_SEEK;
562 128 int64_t filesize = mp3->header_filesize;
563
564
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 128 if (filesize <= 0) {
565 48 int64_t size = avio_size(s->pb);
566
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 48 if (size > 0 && size > si->data_offset)
567 48 filesize = size - si->data_offset;
568 }
569
570
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 128 if (mp3->xing_toc && (mp3->usetoc || (fast_seek && !mp3->is_cbr))) {
571 ✗ int64_t ret = av_index_search_timestamp(st, timestamp, flags);
572
573 // NOTE: The MP3 TOC is not a precise lookup table. Accuracy is worse
574 // for bigger files.
575 ✗ av_log(s, AV_LOG_WARNING, "Using MP3 TOC to seek; may be imprecise.\n");
576
577 ✗ if (ret < 0)
578 ✗ return ret;
579
580 ✗ ie = &sti->index_entries[ret];
581
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 128 } else if (fast_seek && st->duration > 0 && filesize > 0) {
582
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 26 if (!mp3->is_cbr)
583 ✗ av_log(s, AV_LOG_WARNING, "Using scaling to seek VBR MP3; may be imprecise.\n");
584
585 26 ie = &ie1;
586 26 timestamp = av_clip64(timestamp, 0, st->duration);
587 26 ie->timestamp = timestamp;
588 26 ie->pos = av_rescale(timestamp, filesize, st->duration) + si->data_offset;
589 } else {
590 102 return -1; // generic index code
591 }
592
593 26 best_pos = mp3_sync(s, ie->pos, flags);
594
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 26 if (best_pos < 0)
595 ✗ return best_pos;
596
597
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 26 if (mp3->is_cbr && ie == &ie1 && mp3->frames && mp3->header_filesize > 0) {
598 26 ie1.timestamp = mp3->frame_duration * av_rescale(best_pos - si->data_offset, mp3->frames, mp3->header_filesize);
599 }
600
601 26 avpriv_update_cur_dts(s, st, ie->timestamp);
602 26 return 0;
603 }
604
605 static const AVOption options[] = {
606 { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM},
607 { NULL },
608 };
609
610 static const AVClass demuxer_class = {
611 .class_name = "mp3",
612 .item_name = av_default_item_name,
613 .option = options,
614 .version = LIBAVUTIL_VERSION_INT,
615 .category = AV_CLASS_CATEGORY_DEMUXER,
616 };
617
618 const FFInputFormat ff_mp3_demuxer = {
619 .p.name = "mp3",
620 .p.long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
621 .p.flags = AVFMT_GENERIC_INDEX,
622 .p.extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
623 .p.priv_class = &demuxer_class,
624 .p.mime_type = "audio/mpeg",
625 .flags_internal = FF_INFMT_FLAG_ID3V2_AUTO,
626 .read_probe = mp3_read_probe,
627 .read_header = mp3_read_header,
628 .read_packet = mp3_read_packet,
629 .read_seek = mp3_seek,
630 .priv_data_size = sizeof(MP3DecContext),
631 };
632