3 * Copyright (c) 2003 Fabrice Bellard
5 * This file is part of Libav.
7 * Libav 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 * Libav 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 Libav; 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/crc.h"
25 #include "libavutil/dict.h"
26 #include "libavutil/mathematics.h"
29 #include "avio_internal.h"
32 #include "replaygain.h"
34 #include "libavcodec/mpegaudiodecheader.h"
36 #define XING_FLAG_FRAMES 0x01
37 #define XING_FLAG_SIZE 0x02
38 #define XING_FLAG_TOC 0x04
40 #define XING_TOC_COUNT 100
42 typedef struct MP3DecContext {
44 unsigned frames; /* Total number of frames in file */
45 unsigned size; /* Total number of bytes in the stream */
51 static int mp3_read_probe(AVProbeData *p)
53 int max_frames, first_frames = 0;
54 int fsize, frames, sample_rate;
56 uint8_t *buf, *buf0, *buf2, *end;
60 end = p->buf + p->buf_size - sizeof(uint32_t);
61 while(buf0 < end && !*buf0)
67 for(; buf < end; buf= buf2+1) {
70 for(frames = 0; buf2 < end; frames++) {
71 header = AV_RB32(buf2);
72 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
77 max_frames = FFMAX(max_frames, frames);
81 // keep this in sync with ac3 probe, both need to avoid
82 // issues with MPEG-files!
83 if (first_frames >= 10)
84 return AVPROBE_SCORE_EXTENSION + 5;
85 if (first_frames >= 4)
86 return AVPROBE_SCORE_EXTENSION + 1;
90 unsigned int code = -1;
92 #define VIDEO_ID 0x000001e0
93 #define AUDIO_ID 0x000001c0
94 /* do a search for mpegps headers to be able to properly bias
95 * towards mpegps if we detect this stream as both. */
96 for (i = 0; i<p->buf_size; i++) {
97 code = (code << 8) + p->buf[i];
98 if ((code & 0xffffff00) == 0x100) {
99 if ((code & 0x1f0) == VIDEO_ID) pes++;
100 else if((code & 0x1e0) == AUDIO_ID) pes++;
105 max_frames = (max_frames + pes - 1) / pes;
107 if (max_frames > 500) return AVPROBE_SCORE_EXTENSION;
108 else if (max_frames >= 4) return AVPROBE_SCORE_EXTENSION / 2;
109 else if (max_frames >= 1) return 1;
111 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
114 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
117 MP3DecContext *mp3 = s->priv_data;
120 !(filesize = avio_size(s->pb))) {
121 av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
125 for (i = 0; i < XING_TOC_COUNT; i++) {
126 uint8_t b = avio_r8(s->pb);
128 av_add_index_entry(s->streams[0],
129 av_rescale(b, filesize, 256),
130 av_rescale(i, duration, XING_TOC_COUNT),
131 0, 0, AVINDEX_KEYFRAME);
136 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
137 MPADecodeHeader *c, uint32_t spf)
139 #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
140 #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m)))
148 int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
150 MP3DecContext *mp3 = s->priv_data;
151 const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
153 /* Check for Xing / Info tag */
154 avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
155 v = avio_rb32(s->pb);
156 mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
157 if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
160 v = avio_rb32(s->pb);
161 if (v & XING_FLAG_FRAMES)
162 mp3->frames = avio_rb32(s->pb);
163 if (v & XING_FLAG_SIZE)
164 mp3->size = avio_rb32(s->pb);
165 if (v & XING_FLAG_TOC && mp3->frames)
166 read_xing_toc(s, mp3->size, av_rescale_q(mp3->frames,
167 (AVRational){spf, c->sample_rate},
173 /* Encoder short version string */
174 memset(version, 0, sizeof(version));
175 avio_read(s->pb, version, 9);
177 /* Info Tag revision + VBR method */
180 /* Lowpass filter value */
183 /* ReplayGain peak */
184 v = avio_rb32(s->pb);
185 peak = av_rescale(v, 100000, 1 << 23);
187 /* Radio ReplayGain */
188 v = avio_rb16(s->pb);
190 if (MIDDLE_BITS(v, 13, 15) == 1) {
191 r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
197 /* Audiophile ReplayGain */
198 v = avio_rb16(s->pb);
200 if (MIDDLE_BITS(v, 13, 15) == 2) {
201 a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
207 /* Encoding flags + ATH Type */
210 /* if ABR {specified bitrate} else {minimal bitrate} */
222 /* Preset and surround info */
232 crc = ffio_get_checksum(s->pb);
233 v = avio_rb16(s->pb);
236 ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
237 av_dict_set(&st->metadata, "encoder", version, 0);
241 static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
244 MP3DecContext *mp3 = s->priv_data;
246 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
247 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
248 v = avio_rb32(s->pb);
249 if (v == MKBETAG('V', 'B', 'R', 'I')) {
250 /* Check tag version */
251 if (avio_rb16(s->pb) == 1) {
252 /* skip delay and quality */
254 mp3->size = avio_rb32(s->pb);
255 mp3->frames = avio_rb32(s->pb);
261 * Try to find Xing/Info/VBRI tags and compute duration from info therein
263 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
268 MP3DecContext *mp3 = s->priv_data;
270 ffio_init_checksum(s->pb, ff_crcA001_update, 0);
272 v = avio_rb32(s->pb);
273 if(ff_mpa_check_header(v) < 0)
276 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
277 vbrtag_size = c.frame_size;
281 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
286 mp3_parse_info_tag(s, st, &c, spf);
287 mp3_parse_vbri_tag(s, st, base);
289 if (!mp3->frames && !mp3->size)
292 /* Skip the vbr tag frame */
293 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
296 st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate},
298 if (mp3->size && mp3->frames && !mp3->is_cbr)
299 st->codec->bit_rate = av_rescale(mp3->size, 8 * c.sample_rate, mp3->frames * (int64_t)spf);
304 static int mp3_read_header(AVFormatContext *s)
310 st = avformat_new_stream(s, NULL);
312 return AVERROR(ENOMEM);
314 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
315 st->codec->codec_id = AV_CODEC_ID_MP3;
316 st->need_parsing = AVSTREAM_PARSE_FULL;
319 // lcm of all mp3 sample rates
320 avpriv_set_pts_info(st, 64, 1, 14112000);
322 off = avio_tell(s->pb);
324 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
327 if (mp3_parse_vbr_tags(s, st, off) < 0)
328 avio_seek(s->pb, off, SEEK_SET);
330 ret = ff_replaygain_export(st, s->metadata);
334 /* the parameters will be extracted from the compressed bitstream */
338 #define MP3_PACKET_SIZE 1024
340 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
344 ret = av_get_packet(s->pb, pkt, MP3_PACKET_SIZE);
348 pkt->stream_index = 0;
350 if (ret > ID3v1_TAG_SIZE &&
351 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
352 ret -= ID3v1_TAG_SIZE;
354 /* note: we need to modify the packet size here to handle the last
360 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
363 MP3DecContext *mp3 = s->priv_data;
365 AVStream *st = s->streams[0];
366 int64_t ret = av_index_search_timestamp(st, timestamp, flags);
370 return AVERROR(ENOSYS);
375 ie = &st->index_entries[ret];
376 ret = avio_seek(s->pb, ie->pos, SEEK_SET);
380 while (!s->pb->eof_reached) {
381 header = (header << 8) + avio_r8(s->pb);
382 if (ff_mpa_check_header(header) >= 0) {
383 ff_update_cur_dts(s, st, ie->timestamp);
384 ret = avio_seek(s->pb, -4, SEEK_CUR);
385 return (ret >= 0) ? 0 : ret;
392 AVInputFormat ff_mp3_demuxer = {
394 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
395 .read_probe = mp3_read_probe,
396 .read_header = mp3_read_header,
397 .read_packet = mp3_read_packet,
398 .read_seek = mp3_seek,
399 .priv_data_size = sizeof(MP3DecContext),
400 .flags = AVFMT_GENERIC_INDEX,
401 .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */