Signedness bug in Matroska PTS calculation

With some mkv files I had many discontinuity events. I found out that if
changing the timecode_diff in demux_matroska.c from int to int16_t fixes
this problem. Using int will never produce negative values if int is not
16-bit...

1 files changed, 2 insertions, 2 deletions

diff --git a/src/demuxers/demux_matroska.c b/src/demuxers/demux_matroska.c
index 086e0cc98..37f4bd95b 100644
--- a/src/demuxers/demux_matroska.c
+++ b/src/demuxers/demux_matroska.c
@@ -1867,7 +1867,7 @@ static int parse_block (demux_matroska_t *this, size_t block_size,
   uint8_t          *data;
   uint8_t           flags;
   int               gap, lacing, num_len;
-  int               timecode_diff;
+  int16_t           timecode_diff;
   int64_t           pts, xduration;
   int               decoder_flags = 0;
 
@@ -1877,7 +1877,7 @@ static int parse_block (demux_matroska_t *this, size_t block_size,
   data += num_len;
 
   /* timecode_diff is signed */
-  timecode_diff = parse_int16(data);
+  timecode_diff = (int16_t)parse_int16(data);
   data += 2;
 
   flags = *data;