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mp3dec: parse initial silence padding information from lame tag 

And pass the information on to the lavf core.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-07-04 22:01:46 +02:00
parent 018601dbf9
commit 19ff479f69
1 changed files with 28 additions and 0 deletions
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28
libavformat/mp3dec.c
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@ -31,6 +31,8 @@
typedef struct {
int64_t filesize;
int start_pad;
int end_pad;
} MP3Context;
/* mp3 read */
@ -82,6 +84,7 @@ static int mp3_read_probe(AVProbeData *p)
*/
static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
{
MP3Context *mp3 = s->priv_data;
uint32_t v, spf;
unsigned frames = 0; /* Total number of frames in file */
unsigned size = 0; /* Total number of bytes in the stream */
@ -107,6 +110,20 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
frames = avio_rb32(s->pb);
if(v & 0x2)
size = avio_rb32(s->pb);
if(v & 4)
avio_skip(s->pb, 100);
if(v & 8)
avio_skip(s->pb, 4);
v = avio_rb32(s->pb);
if(v == MKBETAG('L', 'A', 'M', 'E')) {
avio_skip(s->pb, 21-4);
v= avio_rb24(s->pb);
mp3->start_pad = v>>12;
mp3-> end_pad = v&4095;
st->skip_samples = mp3->start_pad + 528 + 1;
av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
}
}
/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
@ -206,6 +223,16 @@ static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
return ret;
}
static int read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
{
MP3Context *mp3 = s->priv_data;
AVStream *st = s->streams[stream_index];
st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
return -1;
}
AVInputFormat ff_mp3_demuxer = {
.name = "mp3",
.long_name = NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),
@ -213,6 +240,7 @@ AVInputFormat ff_mp3_demuxer = {
.read_probe = mp3_read_probe,
.read_header = mp3_read_header,
.read_packet = mp3_read_packet,
.read_seek = read_seek,
.flags = AVFMT_GENERIC_INDEX,
.extensions = "mp2,mp3,m2a", /* XXX: use probe */
};