mirror of
https://git.videolan.org/git/ffmpeg.git
synced 2024-09-10 09:31:06 +02:00
287 lines
8.2 KiB
C
287 lines
8.2 KiB
C
/*
|
|
* MP3 demuxer
|
|
* Copyright (c) 2003 Fabrice Bellard
|
|
*
|
|
* This file is part of Libav.
|
|
*
|
|
* Libav is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* Libav is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with Libav; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "libavutil/avstring.h"
|
|
#include "libavutil/intreadwrite.h"
|
|
#include "libavutil/dict.h"
|
|
#include "libavutil/mathematics.h"
|
|
#include "avformat.h"
|
|
#include "internal.h"
|
|
#include "id3v2.h"
|
|
#include "id3v1.h"
|
|
#include "libavcodec/mpegaudiodecheader.h"
|
|
|
|
#define XING_FLAG_FRAMES 0x01
|
|
#define XING_FLAG_SIZE 0x02
|
|
#define XING_FLAG_TOC 0x04
|
|
|
|
#define XING_TOC_COUNT 100
|
|
|
|
typedef struct MP3DecContext {
|
|
int xing_toc;
|
|
} MP3DecContext;
|
|
|
|
/* mp3 read */
|
|
|
|
static int mp3_read_probe(AVProbeData *p)
|
|
{
|
|
int max_frames, first_frames = 0;
|
|
int fsize, frames, sample_rate;
|
|
uint32_t header;
|
|
uint8_t *buf, *buf0, *buf2, *end;
|
|
AVCodecContext avctx;
|
|
|
|
buf0 = p->buf;
|
|
end = p->buf + p->buf_size - sizeof(uint32_t);
|
|
while(buf0 < end && !*buf0)
|
|
buf0++;
|
|
|
|
max_frames = 0;
|
|
buf = buf0;
|
|
|
|
for(; buf < end; buf= buf2+1) {
|
|
buf2 = buf;
|
|
|
|
for(frames = 0; buf2 < end; frames++) {
|
|
header = AV_RB32(buf2);
|
|
fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
|
|
if(fsize < 0)
|
|
break;
|
|
buf2 += fsize;
|
|
}
|
|
max_frames = FFMAX(max_frames, frames);
|
|
if(buf == buf0)
|
|
first_frames= frames;
|
|
}
|
|
// keep this in sync with ac3 probe, both need to avoid
|
|
// issues with MPEG-files!
|
|
if (first_frames >= 4) return AVPROBE_SCORE_EXTENSION + 1;
|
|
|
|
if (max_frames) {
|
|
int pes = 0, i;
|
|
unsigned int code = -1;
|
|
|
|
#define VIDEO_ID 0x000001e0
|
|
#define AUDIO_ID 0x000001c0
|
|
/* do a search for mpegps headers to be able to properly bias
|
|
* towards mpegps if we detect this stream as both. */
|
|
for (i = 0; i<p->buf_size; i++) {
|
|
code = (code << 8) + p->buf[i];
|
|
if ((code & 0xffffff00) == 0x100) {
|
|
if ((code & 0x1f0) == VIDEO_ID) pes++;
|
|
else if((code & 0x1e0) == AUDIO_ID) pes++;
|
|
}
|
|
}
|
|
|
|
if (pes)
|
|
max_frames = (max_frames + pes - 1) / pes;
|
|
}
|
|
if (max_frames > 500) return AVPROBE_SCORE_EXTENSION;
|
|
else if (max_frames >= 4) return AVPROBE_SCORE_EXTENSION / 2;
|
|
else if (max_frames >= 1) return 1;
|
|
else return 0;
|
|
//mpegps_mp3_unrecognized_format.mpg has max_frames=3
|
|
}
|
|
|
|
static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
|
|
{
|
|
int i;
|
|
MP3DecContext *mp3 = s->priv_data;
|
|
|
|
if (!filesize &&
|
|
!(filesize = avio_size(s->pb))) {
|
|
av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
|
|
return;
|
|
}
|
|
|
|
for (i = 0; i < XING_TOC_COUNT; i++) {
|
|
uint8_t b = avio_r8(s->pb);
|
|
|
|
av_add_index_entry(s->streams[0],
|
|
av_rescale(b, filesize, 256),
|
|
av_rescale(i, duration, XING_TOC_COUNT),
|
|
0, 0, AVINDEX_KEYFRAME);
|
|
}
|
|
mp3->xing_toc = 1;
|
|
}
|
|
|
|
/**
|
|
* Try to find Xing/Info/VBRI tags and compute duration from info therein
|
|
*/
|
|
static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
|
|
{
|
|
uint32_t v, spf;
|
|
unsigned frames = 0; /* Total number of frames in file */
|
|
unsigned size = 0; /* Total number of bytes in the stream */
|
|
const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
|
|
MPADecodeHeader c;
|
|
int vbrtag_size = 0;
|
|
int is_cbr;
|
|
|
|
v = avio_rb32(s->pb);
|
|
if(ff_mpa_check_header(v) < 0)
|
|
return -1;
|
|
|
|
if (avpriv_mpegaudio_decode_header(&c, v) == 0)
|
|
vbrtag_size = c.frame_size;
|
|
if(c.layer != 3)
|
|
return -1;
|
|
|
|
spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
|
|
|
|
/* Check for Xing / Info tag */
|
|
avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]);
|
|
v = avio_rb32(s->pb);
|
|
is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
|
|
if (v == MKBETAG('X', 'i', 'n', 'g') || is_cbr) {
|
|
v = avio_rb32(s->pb);
|
|
if(v & XING_FLAG_FRAMES)
|
|
frames = avio_rb32(s->pb);
|
|
if(v & XING_FLAG_SIZE)
|
|
size = avio_rb32(s->pb);
|
|
if (v & XING_FLAG_TOC && frames)
|
|
read_xing_toc(s, size, av_rescale_q(frames, (AVRational){spf, c.sample_rate},
|
|
st->time_base));
|
|
}
|
|
|
|
/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
|
|
avio_seek(s->pb, base + 4 + 32, SEEK_SET);
|
|
v = avio_rb32(s->pb);
|
|
if(v == MKBETAG('V', 'B', 'R', 'I')) {
|
|
/* Check tag version */
|
|
if(avio_rb16(s->pb) == 1) {
|
|
/* skip delay and quality */
|
|
avio_skip(s->pb, 4);
|
|
size = avio_rb32(s->pb);
|
|
frames = avio_rb32(s->pb);
|
|
}
|
|
}
|
|
|
|
if(!frames && !size)
|
|
return -1;
|
|
|
|
/* Skip the vbr tag frame */
|
|
avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
|
|
|
|
if(frames)
|
|
st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
|
|
st->time_base);
|
|
if (size && frames && !is_cbr)
|
|
st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int mp3_read_header(AVFormatContext *s)
|
|
{
|
|
AVStream *st;
|
|
int64_t off;
|
|
|
|
st = avformat_new_stream(s, NULL);
|
|
if (!st)
|
|
return AVERROR(ENOMEM);
|
|
|
|
st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
|
|
st->codec->codec_id = AV_CODEC_ID_MP3;
|
|
st->need_parsing = AVSTREAM_PARSE_FULL;
|
|
st->start_time = 0;
|
|
|
|
// lcm of all mp3 sample rates
|
|
avpriv_set_pts_info(st, 64, 1, 14112000);
|
|
|
|
off = avio_tell(s->pb);
|
|
|
|
if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
|
|
ff_id3v1_read(s);
|
|
|
|
if (mp3_parse_vbr_tags(s, st, off) < 0)
|
|
avio_seek(s->pb, off, SEEK_SET);
|
|
|
|
/* the parameters will be extracted from the compressed bitstream */
|
|
return 0;
|
|
}
|
|
|
|
#define MP3_PACKET_SIZE 1024
|
|
|
|
static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
|
|
{
|
|
int ret;
|
|
|
|
ret = av_get_packet(s->pb, pkt, MP3_PACKET_SIZE);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
pkt->stream_index = 0;
|
|
|
|
if (ret > ID3v1_TAG_SIZE &&
|
|
memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
|
|
ret -= ID3v1_TAG_SIZE;
|
|
|
|
/* note: we need to modify the packet size here to handle the last
|
|
packet */
|
|
pkt->size = ret;
|
|
return ret;
|
|
}
|
|
|
|
static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
|
|
int flags)
|
|
{
|
|
MP3DecContext *mp3 = s->priv_data;
|
|
AVIndexEntry *ie;
|
|
AVStream *st = s->streams[0];
|
|
int64_t ret = av_index_search_timestamp(st, timestamp, flags);
|
|
uint32_t header = 0;
|
|
|
|
if (!mp3->xing_toc)
|
|
return AVERROR(ENOSYS);
|
|
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
ie = &st->index_entries[ret];
|
|
ret = avio_seek(s->pb, ie->pos, SEEK_SET);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
while (!s->pb->eof_reached) {
|
|
header = (header << 8) + avio_r8(s->pb);
|
|
if (ff_mpa_check_header(header) >= 0) {
|
|
ff_update_cur_dts(s, st, ie->timestamp);
|
|
ret = avio_seek(s->pb, -4, SEEK_CUR);
|
|
return (ret >= 0) ? 0 : ret;
|
|
}
|
|
}
|
|
|
|
return AVERROR_EOF;
|
|
}
|
|
|
|
AVInputFormat ff_mp3_demuxer = {
|
|
.name = "mp3",
|
|
.long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
|
|
.read_probe = mp3_read_probe,
|
|
.read_header = mp3_read_header,
|
|
.read_packet = mp3_read_packet,
|
|
.read_seek = mp3_seek,
|
|
.priv_data_size = sizeof(MP3DecContext),
|
|
.flags = AVFMT_GENERIC_INDEX,
|
|
.extensions = "mp2,mp3,m2a", /* XXX: use probe */
|
|
};
|