3 * Copyright (c) 2003 Fabrice Bellard
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavutil/opt.h"
23 #include "libavutil/avstring.h"
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/crc.h"
26 #include "libavutil/dict.h"
27 #include "libavutil/mathematics.h"
30 #include "avio_internal.h"
33 #include "replaygain.h"
35 #include "libavcodec/mpegaudiodecheader.h"
37 #define XING_FLAG_FRAMES 0x01
38 #define XING_FLAG_SIZE 0x02
39 #define XING_FLAG_TOC 0x04
40 #define XING_FLAC_QSCALE 0x08
42 #define XING_TOC_COUNT 100
51 unsigned frames; /* Total number of frames in file */
52 unsigned header_filesize; /* Total number of bytes in the stream */
58 static int mp3_read_probe(AVProbeData *p)
60 int max_frames, first_frames = 0;
63 const uint8_t *buf, *buf0, *buf2, *end;
67 end = p->buf + p->buf_size - sizeof(uint32_t);
68 while(buf0 < end && !*buf0)
74 for(; buf < end; buf= buf2+1) {
76 if(ff_mpa_check_header(AV_RB32(buf2)))
79 for(frames = 0; buf2 < end; frames++) {
81 header = AV_RB32(buf2);
82 fsize = avpriv_mpa_decode_header(&avctx, header, &dummy, &dummy, &dummy, &dummy);
87 max_frames = FFMAX(max_frames, frames);
91 // keep this in sync with ac3 probe, both need to avoid
92 // issues with MPEG-files!
93 if (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
94 else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
95 else if(max_frames>=4 && max_frames >= p->buf_size/10000) return AVPROBE_SCORE_EXTENSION / 2;
96 else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
97 return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2;
98 else if(max_frames>=1 && max_frames >= p->buf_size/10000) return 1;
100 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
103 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
106 MP3DecContext *mp3 = s->priv_data;
107 int fill_index = mp3->usetoc && duration > 0;
110 !(filesize = avio_size(s->pb))) {
111 av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
115 for (i = 0; i < XING_TOC_COUNT; i++) {
116 uint8_t b = avio_r8(s->pb);
118 av_add_index_entry(s->streams[0],
119 av_rescale(b, filesize, 256),
120 av_rescale(i, duration, XING_TOC_COUNT),
121 0, 0, AVINDEX_KEYFRAME);
127 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
128 MPADecodeHeader *c, uint32_t spf)
130 #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
131 #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m)))
139 int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
141 MP3DecContext *mp3 = s->priv_data;
142 static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
143 uint64_t fsize = avio_size(s->pb);
145 /* Check for Xing / Info tag */
146 avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
147 v = avio_rb32(s->pb);
148 mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
149 if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
152 v = avio_rb32(s->pb);
153 if (v & XING_FLAG_FRAMES)
154 mp3->frames = avio_rb32(s->pb);
155 if (v & XING_FLAG_SIZE)
156 mp3->header_filesize = avio_rb32(s->pb);
157 if (fsize && mp3->header_filesize) {
159 min = FFMIN(fsize, mp3->header_filesize);
160 delta = FFMAX(fsize, mp3->header_filesize) - min;
161 if (fsize > mp3->header_filesize && delta > min >> 4) {
163 } else if (delta > min >> 4) {
164 av_log(s, AV_LOG_WARNING,
165 "filesize and duration do not match (growing file?)\n");
168 if (v & XING_FLAG_TOC)
169 read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
170 (AVRational){spf, c->sample_rate},
173 if (v & XING_FLAC_QSCALE)
176 /* Encoder short version string */
177 memset(version, 0, sizeof(version));
178 avio_read(s->pb, version, 9);
180 /* Info Tag revision + VBR method */
183 /* Lowpass filter value */
186 /* ReplayGain peak */
187 v = avio_rb32(s->pb);
188 peak = av_rescale(v, 100000, 1 << 23);
190 /* Radio ReplayGain */
191 v = avio_rb16(s->pb);
193 if (MIDDLE_BITS(v, 13, 15) == 1) {
194 r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
200 /* Audiophile ReplayGain */
201 v = avio_rb16(s->pb);
203 if (MIDDLE_BITS(v, 13, 15) == 2) {
204 a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
210 /* Encoding flags + ATH Type */
213 /* if ABR {specified bitrate} else {minimal bitrate} */
218 if(AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E')
219 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f')
220 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'c')
223 mp3->start_pad = v>>12;
224 mp3-> end_pad = v&4095;
225 st->skip_samples = mp3->start_pad + 528 + 1;
227 st->first_discard_sample = -mp3->end_pad + 528 + 1 + mp3->frames * (int64_t)spf;
228 st->last_discard_sample = mp3->frames * (int64_t)spf;
231 st->start_time = av_rescale_q(st->skip_samples,
232 (AVRational){1, c->sample_rate},
234 av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
243 /* Preset and surround info */
253 crc = ffio_get_checksum(s->pb);
254 v = avio_rb16(s->pb);
257 ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
258 av_dict_set(&st->metadata, "encoder", version, 0);
262 static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
265 MP3DecContext *mp3 = s->priv_data;
267 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
268 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
269 v = avio_rb32(s->pb);
270 if (v == MKBETAG('V', 'B', 'R', 'I')) {
271 /* Check tag version */
272 if (avio_rb16(s->pb) == 1) {
273 /* skip delay and quality */
275 mp3->header_filesize = avio_rb32(s->pb);
276 mp3->frames = avio_rb32(s->pb);
282 * Try to find Xing/Info/VBRI tags and compute duration from info therein
284 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
289 MP3DecContext *mp3 = s->priv_data;
291 ffio_init_checksum(s->pb, ff_crcA001_update, 0);
293 v = avio_rb32(s->pb);
294 if(ff_mpa_check_header(v) < 0)
297 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
298 vbrtag_size = c.frame_size;
302 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
305 mp3->header_filesize = 0;
307 mp3_parse_info_tag(s, st, &c, spf);
308 mp3_parse_vbri_tag(s, st, base);
310 if (!mp3->frames && !mp3->header_filesize)
313 /* Skip the vbr tag frame */
314 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
317 st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate},
319 if (mp3->header_filesize && mp3->frames && !mp3->is_cbr)
320 st->codec->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf);
325 static int mp3_read_header(AVFormatContext *s)
327 MP3DecContext *mp3 = s->priv_data;
332 st = avformat_new_stream(s, NULL);
334 return AVERROR(ENOMEM);
336 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
337 st->codec->codec_id = AV_CODEC_ID_MP3;
338 st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
341 // lcm of all mp3 sample rates
342 avpriv_set_pts_info(st, 64, 1, 14112000);
345 off = avio_tell(s->pb);
347 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
351 mp3->filesize = avio_size(s->pb);
353 if (mp3_parse_vbr_tags(s, st, off) < 0)
354 avio_seek(s->pb, off, SEEK_SET);
356 ret = ff_replaygain_export(st, s->metadata);
360 /* the parameters will be extracted from the compressed bitstream */
364 #define MP3_PACKET_SIZE 1024
366 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
368 MP3DecContext *mp3 = s->priv_data;
372 size= MP3_PACKET_SIZE;
373 pos = avio_tell(s->pb);
374 if(mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
375 size= FFMIN(size, mp3->filesize - pos);
377 ret= av_get_packet(s->pb, pkt, size);
384 pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
385 pkt->stream_index = 0;
387 if (ret >= ID3v1_TAG_SIZE &&
388 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
389 ret -= ID3v1_TAG_SIZE;
391 /* note: we need to modify the packet size here to handle the last
397 static int check(AVFormatContext *s, int64_t pos)
399 int64_t ret = avio_seek(s->pb, pos, SEEK_SET);
404 header = avio_rb32(s->pb);
405 if (ff_mpa_check_header(header) < 0)
407 if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
409 return sd.frame_size;
412 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
415 MP3DecContext *mp3 = s->priv_data;
416 AVIndexEntry *ie, ie1;
417 AVStream *st = s->streams[0];
418 int64_t ret = av_index_search_timestamp(st, timestamp, flags);
420 int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
426 && mp3->header_filesize > s->internal->data_offset
428 int64_t filesize = avio_size(s->pb);
430 if (filesize <= s->internal->data_offset)
431 filesize = mp3->header_filesize;
432 filesize -= s->internal->data_offset;
433 duration = av_rescale(st->duration, filesize, mp3->header_filesize - s->internal->data_offset);
435 timestamp = av_clip64(timestamp, 0, duration);
436 ie->timestamp = timestamp;
437 ie->pos = av_rescale(timestamp, filesize, duration) + s->internal->data_offset;
438 } else if (mp3->xing_toc) {
442 ie = &st->index_entries[ret];
444 st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
449 avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
450 ret = avio_seek(s->pb, ie->pos, SEEK_SET);
457 for(i=0; i<4096; i++) {
458 int64_t pos = ie->pos + (dir > 0 ? i - 1024 : -i);
459 int64_t candidate = -1;
465 for(j=0; j<MIN_VALID; j++) {
469 if ((ie->pos - pos)*dir <= 0 && abs(MIN_VALID/2-j) < score) {
471 score = abs(MIN_VALID/2-j);
475 if (best_score > score && j == MIN_VALID) {
476 best_pos = candidate;
483 ret = avio_seek(s->pb, best_pos, SEEK_SET);
486 ff_update_cur_dts(s, st, ie->timestamp);
487 st->skip_samples = ie->timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
491 static const AVOption options[] = {
492 { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},
496 static const AVClass demuxer_class = {
498 .item_name = av_default_item_name,
500 .version = LIBAVUTIL_VERSION_INT,
501 .category = AV_CLASS_CATEGORY_DEMUXER,
504 AVInputFormat ff_mp3_demuxer = {
506 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
507 .read_probe = mp3_read_probe,
508 .read_header = mp3_read_header,
509 .read_packet = mp3_read_packet,
510 .read_seek = mp3_seek,
511 .priv_data_size = sizeof(MP3DecContext),
512 .flags = AVFMT_GENERIC_INDEX,
513 .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
514 .priv_class = &demuxer_class,