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libavformat/matroskadec: fix unsigned overflow to improve seeking 

When seeking a file where codec delay is greater than 0, the timecode
can become negative after offsetting by the codec delay. Failing to cast
to a signed int64 will cause the check against skip_to_timecode to evaluate
true for these negative values. This breaks the "skip_to" seek mechanism.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Chris Cunningham 2016-07-21 12:01:45 -07:00 committed by Michael Niedermayer
parent 0a088dea3d
commit d59820f6fe
1 changed files with 4 additions and 1 deletions
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5
libavformat/matroskadec.c
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@ -3150,7 +3150,10 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
if (matroska->skip_to_keyframe &&
track->type != MATROSKA_TRACK_TYPE_SUBTITLE) {
if (timecode < matroska->skip_to_timecode)
// Compare signed timecodes. Timecode may be negative due to codec delay
// offset. We don't support timestamps greater than int64_t anyway - see
// AVPacket's pts.
if ((int64_t)timecode < (int64_t)(matroska->skip_to_timecode))
return res;
if (is_keyframe)
matroska->skip_to_keyframe = 0;