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improve ac3_probe by counting consecutive frames 

Originally committed as revision 8441 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-03-18 19:32:22 +00:00
parent 9a44385e1a
commit f8b9830b6c
1 changed files with 24 additions and 8 deletions
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32
libavformat/raw.c
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@ -20,6 +20,7 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "ac3.h"
#ifdef CONFIG_MUXERS
/* simple formats */
@ -408,18 +409,33 @@ static int h261_probe(AVProbeData *p)
static int ac3_probe(AVProbeData *p)
{
int score=0;
int max_frames, first_frames, frames;
uint8_t *buf, *buf2, *end;
AC3HeaderInfo hdr;
if(p->buf_size < 6)
if(p->buf_size < 7)
return 0;
if((p->buf[0] == 0x0B) && (p->buf[1] == 0x77) && // sync word
((p->buf[4] >> 6) != 3) && // fscod
((p->buf[5] >> 3) <= 16)) { // bsid
score = AVPROBE_SCORE_MAX / 2 + 10;
}
max_frames = 0;
buf = p->buf;
end = buf + FFMIN(4096, p->buf_size - 7);
return score;
for(; buf < end; buf++) {
buf2 = buf;
for(frames = 0; buf2 < end; frames++) {
if(ff_ac3_parse_header(buf2, &hdr) < 0)
break;
buf2 += hdr.frame_size;
}
max_frames = FFMAX(max_frames, frames);
if(buf == p->buf)
first_frames = frames;
}
if (first_frames>=3) return AVPROBE_SCORE_MAX * 3 / 4;
else if(max_frames>=3) return AVPROBE_SCORE_MAX / 2;
else if(max_frames>=1) return 1;
else return 0;
}
AVInputFormat shorten_demuxer = {