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
41 #define XING_TOC_COUNT 100
50 unsigned frames; /* Total number of frames in file */
51 unsigned header_filesize; /* Total number of bytes in the stream */
57 static int mp3_read_probe(AVProbeData *p)
59 int max_frames, first_frames = 0;
60 int fsize, frames, sample_rate;
62 const uint8_t *buf, *buf0, *buf2, *end;
66 end = p->buf + p->buf_size - sizeof(uint32_t);
67 while(buf0 < end && !*buf0)
73 for(; buf < end; buf= buf2+1) {
75 if(ff_mpa_check_header(AV_RB32(buf2)))
78 for(frames = 0; buf2 < end; frames++) {
79 header = AV_RB32(buf2);
80 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
85 max_frames = FFMAX(max_frames, frames);
89 // keep this in sync with ac3 probe, both need to avoid
90 // issues with MPEG-files!
91 if (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
92 else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
93 else if(max_frames>=4 && max_frames >= p->buf_size/10000) return AVPROBE_SCORE_EXTENSION / 2;
94 else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
95 return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2;
96 else if(max_frames>=1 && max_frames >= p->buf_size/10000) return 1;
98 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
101 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
104 MP3DecContext *mp3 = s->priv_data;
105 int fill_index = mp3->usetoc && duration > 0;
108 !(filesize = avio_size(s->pb))) {
109 av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
113 for (i = 0; i < XING_TOC_COUNT; i++) {
114 uint8_t b = avio_r8(s->pb);
116 av_add_index_entry(s->streams[0],
117 av_rescale(b, filesize, 256),
118 av_rescale(i, duration, XING_TOC_COUNT),
119 0, 0, AVINDEX_KEYFRAME);
125 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
126 MPADecodeHeader *c, uint32_t spf)
128 #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
129 #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m)))
137 int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
139 MP3DecContext *mp3 = s->priv_data;
140 static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
142 /* Check for Xing / Info tag */
143 avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
144 v = avio_rb32(s->pb);
145 mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
146 if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
149 v = avio_rb32(s->pb);
150 if (v & XING_FLAG_FRAMES)
151 mp3->frames = avio_rb32(s->pb);
152 if (v & XING_FLAG_SIZE)
153 mp3->header_filesize = avio_rb32(s->pb);
154 if (v & XING_FLAG_TOC)
155 read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
156 (AVRational){spf, c->sample_rate},
162 /* Encoder short version string */
163 memset(version, 0, sizeof(version));
164 avio_read(s->pb, version, 9);
166 /* Info Tag revision + VBR method */
169 /* Lowpass filter value */
172 /* ReplayGain peak */
173 v = avio_rb32(s->pb);
174 peak = av_rescale(v, 100000, 1 << 23);
176 /* Radio ReplayGain */
177 v = avio_rb16(s->pb);
179 if (MIDDLE_BITS(v, 13, 15) == 1) {
180 r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
186 /* Audiophile ReplayGain */
187 v = avio_rb16(s->pb);
189 if (MIDDLE_BITS(v, 13, 15) == 2) {
190 a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
196 /* Encoding flags + ATH Type */
199 /* if ABR {specified bitrate} else {minimal bitrate} */
204 if(AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E')
205 || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f')) {
207 mp3->start_pad = v>>12;
208 mp3-> end_pad = v&4095;
209 st->skip_samples = mp3->start_pad + 528 + 1;
211 st->start_time = av_rescale_q(st->skip_samples,
212 (AVRational){1, c->sample_rate},
214 av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
223 /* Preset and surround info */
233 crc = ffio_get_checksum(s->pb);
234 v = avio_rb16(s->pb);
237 ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
238 av_dict_set(&st->metadata, "encoder", version, 0);
242 static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
245 MP3DecContext *mp3 = s->priv_data;
247 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
248 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
249 v = avio_rb32(s->pb);
250 if (v == MKBETAG('V', 'B', 'R', 'I')) {
251 /* Check tag version */
252 if (avio_rb16(s->pb) == 1) {
253 /* skip delay and quality */
255 mp3->header_filesize = avio_rb32(s->pb);
256 mp3->frames = avio_rb32(s->pb);
262 * Try to find Xing/Info/VBRI tags and compute duration from info therein
264 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
269 MP3DecContext *mp3 = s->priv_data;
271 ffio_init_checksum(s->pb, ff_crcA001_update, 0);
273 v = avio_rb32(s->pb);
274 if(ff_mpa_check_header(v) < 0)
277 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
278 vbrtag_size = c.frame_size;
282 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
285 mp3->header_filesize = 0;
287 mp3_parse_info_tag(s, st, &c, spf);
288 mp3_parse_vbri_tag(s, st, base);
290 if (!mp3->frames && !mp3->header_filesize)
293 /* Skip the vbr tag frame */
294 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
297 st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate},
299 if (mp3->header_filesize && mp3->frames && !mp3->is_cbr)
300 st->codec->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf);
305 static int mp3_read_header(AVFormatContext *s)
307 MP3DecContext *mp3 = s->priv_data;
312 st = avformat_new_stream(s, NULL);
314 return AVERROR(ENOMEM);
316 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
317 st->codec->codec_id = AV_CODEC_ID_MP3;
318 st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
321 // lcm of all mp3 sample rates
322 avpriv_set_pts_info(st, 64, 1, 14112000);
325 off = avio_tell(s->pb);
327 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
331 mp3->filesize = avio_size(s->pb);
333 if (mp3_parse_vbr_tags(s, st, off) < 0)
334 avio_seek(s->pb, off, SEEK_SET);
336 ret = ff_replaygain_export(st, s->metadata);
340 /* the parameters will be extracted from the compressed bitstream */
344 #define MP3_PACKET_SIZE 1024
346 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
348 MP3DecContext *mp3 = s->priv_data;
352 size= MP3_PACKET_SIZE;
353 pos = avio_tell(s->pb);
354 if(mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
355 size= FFMIN(size, mp3->filesize - pos);
357 ret= av_get_packet(s->pb, pkt, size);
364 pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
365 pkt->stream_index = 0;
367 if (ret >= ID3v1_TAG_SIZE &&
368 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
369 ret -= ID3v1_TAG_SIZE;
371 /* note: we need to modify the packet size here to handle the last
377 static int check(AVFormatContext *s, int64_t pos)
379 int64_t ret = avio_seek(s->pb, pos, SEEK_SET);
384 header = avio_rb32(s->pb);
385 if (ff_mpa_check_header(header) < 0)
387 if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
389 return sd.frame_size;
392 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
395 MP3DecContext *mp3 = s->priv_data;
396 AVIndexEntry *ie, ie1;
397 AVStream *st = s->streams[0];
398 int64_t ret = av_index_search_timestamp(st, timestamp, flags);
400 int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
402 if (mp3->is_cbr && st->duration > 0 && mp3->header_filesize > s->data_offset) {
403 int64_t filesize = avio_size(s->pb);
405 if (filesize <= s->data_offset)
406 filesize = mp3->header_filesize;
407 filesize -= s->data_offset;
408 duration = av_rescale(st->duration, filesize, mp3->header_filesize - s->data_offset);
410 timestamp = av_clip64(timestamp, 0, duration);
411 ie->timestamp = timestamp;
412 ie->pos = av_rescale(timestamp, filesize, duration) + s->data_offset;
413 } else if (mp3->xing_toc) {
417 ie = &st->index_entries[ret];
419 st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
425 avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
426 ret = avio_seek(s->pb, ie->pos, SEEK_SET);
431 for(i=0; i<4096; i++) {
432 int64_t pos = ie->pos + i*dir;
433 for(j=0; j<MIN_VALID; j++) {
445 ret = avio_seek(s->pb, ie->pos + i*dir, SEEK_SET);
448 ff_update_cur_dts(s, st, ie->timestamp);
449 st->skip_samples = ie->timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
453 static const AVOption options[] = {
454 { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},
458 static const AVClass demuxer_class = {
460 .item_name = av_default_item_name,
462 .version = LIBAVUTIL_VERSION_INT,
463 .category = AV_CLASS_CATEGORY_DEMUXER,
466 AVInputFormat ff_mp3_demuxer = {
468 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
469 .read_probe = mp3_read_probe,
470 .read_header = mp3_read_header,
471 .read_packet = mp3_read_packet,
472 .read_seek = mp3_seek,
473 .priv_data_size = sizeof(MP3DecContext),
474 .flags = AVFMT_GENERIC_INDEX,
475 .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
476 .priv_class = &demuxer_class,