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;
61 int fsize, frames, sample_rate;
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++) {
80 header = AV_RB32(buf2);
81 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
86 max_frames = FFMAX(max_frames, frames);
90 // keep this in sync with ac3 probe, both need to avoid
91 // issues with MPEG-files!
92 if (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
93 else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
94 else if(max_frames>=4 && max_frames >= p->buf_size/10000) return AVPROBE_SCORE_EXTENSION / 2;
95 else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
96 return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2;
97 else if(max_frames>=1 && max_frames >= p->buf_size/10000) return 1;
99 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
102 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
105 MP3DecContext *mp3 = s->priv_data;
106 int fill_index = mp3->usetoc && duration > 0;
109 !(filesize = avio_size(s->pb))) {
110 av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
114 for (i = 0; i < XING_TOC_COUNT; i++) {
115 uint8_t b = avio_r8(s->pb);
117 av_add_index_entry(s->streams[0],
118 av_rescale(b, filesize, 256),
119 av_rescale(i, duration, XING_TOC_COUNT),
120 0, 0, AVINDEX_KEYFRAME);
126 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
127 MPADecodeHeader *c, uint32_t spf)
129 #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
130 #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m)))
138 int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
140 MP3DecContext *mp3 = s->priv_data;
141 static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
142 uint64_t fsize = avio_size(s->pb);
144 /* Check for Xing / Info tag */
145 avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
146 v = avio_rb32(s->pb);
147 mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
148 if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
151 v = avio_rb32(s->pb);
152 if (v & XING_FLAG_FRAMES)
153 mp3->frames = avio_rb32(s->pb);
154 if (v & XING_FLAG_SIZE)
155 mp3->header_filesize = avio_rb32(s->pb);
156 if (fsize && mp3->header_filesize) {
158 min = FFMIN(fsize, mp3->header_filesize);
159 delta = FFMAX(fsize, mp3->header_filesize) - min;
160 if (fsize > mp3->header_filesize && delta > min >> 4) {
162 } else if (delta > min >> 4) {
163 av_log(s, AV_LOG_WARNING,
164 "filesize and duration do not match (growing file?)\n");
167 if (v & XING_FLAG_TOC)
168 read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
169 (AVRational){spf, c->sample_rate},
172 if (v & XING_FLAC_QSCALE)
175 /* Encoder short version string */
176 memset(version, 0, sizeof(version));
177 avio_read(s->pb, version, 9);
179 /* Info Tag revision + VBR method */
182 /* Lowpass filter value */
185 /* ReplayGain peak */
186 v = avio_rb32(s->pb);
187 peak = av_rescale(v, 100000, 1 << 23);
189 /* Radio ReplayGain */
190 v = avio_rb16(s->pb);
192 if (MIDDLE_BITS(v, 13, 15) == 1) {
193 r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
199 /* Audiophile ReplayGain */
200 v = avio_rb16(s->pb);
202 if (MIDDLE_BITS(v, 13, 15) == 2) {
203 a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
209 /* Encoding flags + ATH Type */
212 /* if ABR {specified bitrate} else {minimal bitrate} */
217 if(AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E')
218 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f')
219 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'c')
222 mp3->start_pad = v>>12;
223 mp3-> end_pad = v&4095;
224 st->skip_samples = mp3->start_pad + 528 + 1;
226 st->first_discard_sample = -mp3->end_pad + 528 + 1 + mp3->frames * (int64_t)spf;
227 st->last_discard_sample = mp3->frames * (int64_t)spf;
230 st->start_time = av_rescale_q(st->skip_samples,
231 (AVRational){1, c->sample_rate},
233 av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
242 /* Preset and surround info */
252 crc = ffio_get_checksum(s->pb);
253 v = avio_rb16(s->pb);
256 ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
257 av_dict_set(&st->metadata, "encoder", version, 0);
261 static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
264 MP3DecContext *mp3 = s->priv_data;
266 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
267 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
268 v = avio_rb32(s->pb);
269 if (v == MKBETAG('V', 'B', 'R', 'I')) {
270 /* Check tag version */
271 if (avio_rb16(s->pb) == 1) {
272 /* skip delay and quality */
274 mp3->header_filesize = avio_rb32(s->pb);
275 mp3->frames = avio_rb32(s->pb);
281 * Try to find Xing/Info/VBRI tags and compute duration from info therein
283 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
288 MP3DecContext *mp3 = s->priv_data;
290 ffio_init_checksum(s->pb, ff_crcA001_update, 0);
292 v = avio_rb32(s->pb);
293 if(ff_mpa_check_header(v) < 0)
296 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
297 vbrtag_size = c.frame_size;
301 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
304 mp3->header_filesize = 0;
306 mp3_parse_info_tag(s, st, &c, spf);
307 mp3_parse_vbri_tag(s, st, base);
309 if (!mp3->frames && !mp3->header_filesize)
312 /* Skip the vbr tag frame */
313 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
316 st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate},
318 if (mp3->header_filesize && mp3->frames && !mp3->is_cbr)
319 st->codec->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf);
324 static int mp3_read_header(AVFormatContext *s)
326 MP3DecContext *mp3 = s->priv_data;
331 st = avformat_new_stream(s, NULL);
333 return AVERROR(ENOMEM);
335 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
336 st->codec->codec_id = AV_CODEC_ID_MP3;
337 st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
340 // lcm of all mp3 sample rates
341 avpriv_set_pts_info(st, 64, 1, 14112000);
344 off = avio_tell(s->pb);
346 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
350 mp3->filesize = avio_size(s->pb);
352 if (mp3_parse_vbr_tags(s, st, off) < 0)
353 avio_seek(s->pb, off, SEEK_SET);
355 ret = ff_replaygain_export(st, s->metadata);
359 /* the parameters will be extracted from the compressed bitstream */
363 #define MP3_PACKET_SIZE 1024
365 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
367 MP3DecContext *mp3 = s->priv_data;
371 size= MP3_PACKET_SIZE;
372 pos = avio_tell(s->pb);
373 if(mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
374 size= FFMIN(size, mp3->filesize - pos);
376 ret= av_get_packet(s->pb, pkt, size);
383 pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
384 pkt->stream_index = 0;
386 if (ret >= ID3v1_TAG_SIZE &&
387 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
388 ret -= ID3v1_TAG_SIZE;
390 /* note: we need to modify the packet size here to handle the last
396 static int check(AVFormatContext *s, int64_t pos)
398 int64_t ret = avio_seek(s->pb, pos, SEEK_SET);
403 header = avio_rb32(s->pb);
404 if (ff_mpa_check_header(header) < 0)
406 if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
408 return sd.frame_size;
411 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
414 MP3DecContext *mp3 = s->priv_data;
415 AVIndexEntry *ie, ie1;
416 AVStream *st = s->streams[0];
417 int64_t ret = av_index_search_timestamp(st, timestamp, flags);
419 int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
425 && mp3->header_filesize > s->data_offset
427 int64_t filesize = avio_size(s->pb);
429 if (filesize <= s->data_offset)
430 filesize = mp3->header_filesize;
431 filesize -= s->data_offset;
432 duration = av_rescale(st->duration, filesize, mp3->header_filesize - s->data_offset);
434 timestamp = av_clip64(timestamp, 0, duration);
435 ie->timestamp = timestamp;
436 ie->pos = av_rescale(timestamp, filesize, duration) + s->data_offset;
437 } else if (mp3->xing_toc) {
441 ie = &st->index_entries[ret];
443 st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
448 avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
449 ret = avio_seek(s->pb, ie->pos, SEEK_SET);
456 for(i=0; i<4096; i++) {
457 int64_t pos = ie->pos + (dir > 0 ? i - 1024 : -i);
458 int64_t candidate = -1;
460 for(j=0; j<MIN_VALID; j++) {
464 if ((ie->pos - pos)*dir <= 0 && abs(MIN_VALID/2-j) < score) {
466 score = abs(MIN_VALID/2-j);
470 if (best_score > score && j == MIN_VALID) {
471 best_pos = candidate;
478 ret = avio_seek(s->pb, best_pos, SEEK_SET);
481 ff_update_cur_dts(s, st, ie->timestamp);
482 st->skip_samples = ie->timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
486 static const AVOption options[] = {
487 { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},
491 static const AVClass demuxer_class = {
493 .item_name = av_default_item_name,
495 .version = LIBAVUTIL_VERSION_INT,
496 .category = AV_CLASS_CATEGORY_DEMUXER,
499 AVInputFormat ff_mp3_demuxer = {
501 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
502 .read_probe = mp3_read_probe,
503 .read_header = mp3_read_header,
504 .read_packet = mp3_read_packet,
505 .read_seek = mp3_seek,
506 .priv_data_size = sizeof(MP3DecContext),
507 .flags = AVFMT_GENERIC_INDEX,
508 .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
509 .priv_class = &demuxer_class,