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Extend DV autodetection to also reliably detect single-frame DVs with 

a higher score that MAX/4.
It checks that there are at least 10 DIF headers and at least one per
24000 bytes, and if so considers the file reliably detected as DV.
Passes probetest, too.

Originally committed as revision 20074 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger 2009-09-29 10:12:18 +00:00
parent 6378b06208
commit f6765f3f04
1 changed files with 6 additions and 1 deletions
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7
libavformat/dv.c
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@ -489,6 +489,7 @@ static int dv_probe(AVProbeData *p)
unsigned state, marker_pos = 0;
int i;
int matches = 0;
int secondary_matches = 0;
if (p->buf_size < 5)
return 0;
@ -497,6 +498,10 @@ static int dv_probe(AVProbeData *p)
for (i = 4; i < p->buf_size; i++) {
if ((state & 0xffffff7f) == 0x1f07003f)
matches++;
// any section header, also with seq/chan num != 0,
// should appear around every 12000 bytes, at least 10 per frame
if ((state & 0xff07ff7f) == 0x1f07003f)
secondary_matches++;
if (state == 0x003f0700 || state == 0xff3f0700)
marker_pos = i;
if (state == 0xff3f0701 && i - marker_pos == 80)
@ -505,7 +510,7 @@ static int dv_probe(AVProbeData *p)
}
if (matches && p->buf_size / matches < 1024*1024) {
if (matches > 4)
if (matches > 4 || (secondary_matches >= 10 && p->buf_size / secondary_matches < 24000))
return AVPROBE_SCORE_MAX*3/4; // not max to avoid dv in mov to match
return AVPROBE_SCORE_MAX/4;
}