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/avstring.h"
23 #include "libavutil/intreadwrite.h"
24 #include "libavutil/dict.h"
25 #include "libavutil/mathematics.h"
30 #include "libavcodec/mpegaudiodecheader.h"
32 #define XING_FLAG_FRAMES 0x01
33 #define XING_FLAG_SIZE 0x02
34 #define XING_FLAG_TOC 0x04
36 #define XING_TOC_COUNT 100
47 static int mp3_read_probe(AVProbeData *p)
49 int max_frames, first_frames = 0;
50 int fsize, frames, sample_rate;
52 const uint8_t *buf, *buf0, *buf2, *end;
56 end = p->buf + p->buf_size - sizeof(uint32_t);
57 while(buf0 < end && !*buf0)
63 for(; buf < end; buf= buf2+1) {
66 for(frames = 0; buf2 < end; frames++) {
67 header = AV_RB32(buf2);
68 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
73 max_frames = FFMAX(max_frames, frames);
77 // keep this in sync with ac3 probe, both need to avoid
78 // issues with MPEG-files!
79 if (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
80 else if(max_frames>200)return AVPROBE_SCORE_MAX/2;
81 else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
82 else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
83 return AVPROBE_SCORE_MAX/8;
84 else if(max_frames>=1) return 1;
86 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
89 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
92 MP3Context *mp3 = s->priv_data;
95 !(filesize = avio_size(s->pb))) {
96 av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
100 for (i = 0; i < XING_TOC_COUNT; i++) {
101 uint8_t b = avio_r8(s->pb);
103 av_add_index_entry(s->streams[0],
104 av_rescale(b, filesize, 256),
105 av_rescale(i, duration, XING_TOC_COUNT),
106 0, 0, AVINDEX_KEYFRAME);
112 * Try to find Xing/Info/VBRI tags and compute duration from info therein
114 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
116 MP3Context *mp3 = s->priv_data;
118 unsigned frames = 0; /* Total number of frames in file */
119 unsigned size = 0; /* Total number of bytes in the stream */
120 const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
124 v = avio_rb32(s->pb);
125 if(ff_mpa_check_header(v) < 0)
128 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
129 vbrtag_size = c.frame_size;
133 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
135 /* Check for Xing / Info tag */
136 avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]);
137 v = avio_rb32(s->pb);
138 if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
139 v = avio_rb32(s->pb);
140 if(v & XING_FLAG_FRAMES)
141 frames = avio_rb32(s->pb);
142 if(v & XING_FLAG_SIZE)
143 size = avio_rb32(s->pb);
144 if (v & XING_FLAG_TOC && frames)
145 read_xing_toc(s, size, av_rescale_q(frames, (AVRational){spf, c.sample_rate},
150 v = avio_rb32(s->pb);
151 if(v == MKBETAG('L', 'A', 'M', 'E') || v == MKBETAG('L', 'a', 'v', 'f')) {
152 avio_skip(s->pb, 21-4);
154 mp3->start_pad = v>>12;
155 mp3-> end_pad = v&4095;
156 st->skip_samples = mp3->start_pad + 528 + 1;
157 av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
161 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
162 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
163 v = avio_rb32(s->pb);
164 if(v == MKBETAG('V', 'B', 'R', 'I')) {
165 /* Check tag version */
166 if(avio_rb16(s->pb) == 1) {
167 /* skip delay and quality */
169 size = avio_rb32(s->pb);
170 frames = avio_rb32(s->pb);
177 /* Skip the vbr tag frame */
178 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
181 st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
184 st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
189 static int mp3_read_header(AVFormatContext *s)
191 MP3Context *mp3 = s->priv_data;
195 st = avformat_new_stream(s, NULL);
197 return AVERROR(ENOMEM);
199 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
200 st->codec->codec_id = AV_CODEC_ID_MP3;
201 st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
204 // lcm of all mp3 sample rates
205 avpriv_set_pts_info(st, 64, 1, 14112000);
208 off = avio_tell(s->pb);
210 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
214 mp3->filesize = avio_size(s->pb);
216 if (mp3_parse_vbr_tags(s, st, off) < 0)
217 avio_seek(s->pb, off, SEEK_SET);
219 /* the parameters will be extracted from the compressed bitstream */
223 #define MP3_PACKET_SIZE 1024
225 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
227 MP3Context *mp3 = s->priv_data;
231 size= MP3_PACKET_SIZE;
232 pos = avio_tell(s->pb);
233 if(mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
234 size= FFMIN(size, mp3->filesize - pos);
236 ret= av_get_packet(s->pb, pkt, size);
243 pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
244 pkt->stream_index = 0;
246 if (ret >= ID3v1_TAG_SIZE &&
247 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
248 ret -= ID3v1_TAG_SIZE;
250 /* note: we need to modify the packet size here to handle the last
256 static int check(AVFormatContext *s, int64_t pos)
258 int64_t ret = avio_seek(s->pb, pos, SEEK_SET);
263 header = avio_rb32(s->pb);
264 if (ff_mpa_check_header(header) < 0)
266 if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
268 return sd.frame_size;
271 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
274 MP3Context *mp3 = s->priv_data;
276 AVStream *st = s->streams[0];
277 int64_t ret = av_index_search_timestamp(st, timestamp, flags);
280 if (!mp3->xing_toc) {
281 st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
289 ie = &st->index_entries[ret];
290 ret = avio_seek(s->pb, ie->pos, SEEK_SET);
295 for(i=0; i<4096; i++) {
296 int64_t pos = ie->pos + i;
297 for(j=0; j<MIN_VALID; j++) {
309 ret = avio_seek(s->pb, ie->pos + i, SEEK_SET);
312 ff_update_cur_dts(s, st, ie->timestamp);
313 st->skip_samples = ie->timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
317 AVInputFormat ff_mp3_demuxer = {
319 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
320 .priv_data_size = sizeof(MP3Context),
321 .read_probe = mp3_read_probe,
322 .read_header = mp3_read_header,
323 .read_packet = mp3_read_packet,
324 .read_seek = mp3_seek,
325 .flags = AVFMT_GENERIC_INDEX,
326 .extensions = "mp2,mp3,m2a", /* XXX: use probe */