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Make DTS probe more robust against false positives (as e.g. probetest shows).

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In particular check that the detected markers clearly indicate a specific DTS
format (a wild mixture of e.g. little- and big-endian markers is unlikely to be
a valid DTS file) and ensure the markers appear with sufficient frequency.

Originally committed as revision 19844 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger 2009-09-14 20:28:10 +00:00
parent 9f449d57c7
commit 05bdd33a12
1 changed files with 11 additions and 3 deletions
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14
libavformat/raw.c
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@ -510,6 +510,8 @@ static int dts_probe(AVProbeData *p)
{
const uint8_t *buf, *bufp;
uint32_t state = -1;
int markers[3] = {0};
int sum, max;
buf = p->buf;
@ -519,18 +521,24 @@ static int dts_probe(AVProbeData *p)
/* regular bitstream */
if (state == DCA_MARKER_RAW_BE || state == DCA_MARKER_RAW_LE)
return AVPROBE_SCORE_MAX/2+1;
markers[0]++;
/* 14 bits big-endian bitstream */
if (state == DCA_MARKER_14B_BE)
if ((bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
return AVPROBE_SCORE_MAX/2+1;
markers[1]++;
/* 14 bits little-endian bitstream */
if (state == DCA_MARKER_14B_LE)
if ((bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
return AVPROBE_SCORE_MAX/2+1;
markers[2]++;
}
sum = markers[0] + markers[1] + markers[2];
max = markers[1] > markers[0];
max = markers[2] > markers[max] ? 2 : max;
if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
markers[max] * 4 > sum * 3)
return AVPROBE_SCORE_MAX/2+1;
return 0;
}