[vlc-devel] Possible bug in ps demuxer

RATH, CHRISTOPHER A (CHRISTOPHER A) car at research.att.com
Wed Sep 9 15:17:13 CEST 2009

I have been trying to figure out why some mpeg-2 content we are pulling from
a video tuner card is not playing on the latest VLC.  The tuner card is
putting closed-captioning information in the mpeg-2 as a private stream.
The Pack Header packets that precede the closed-captioning private stream
packets have an SCR of 400400.  I am not sure why this is happening or if it
is expected.

In the Demux function, the default case in the switch on the stream ID is
checking to see if the stream ID >= 0xc0, which would indicate it is an
audio or video stream, and if so, it populates the track and processes the

The problem, I believe, is that VOB extension packets have a stream ID of
0xbdNN, where NN is the substream number.  0xbdNN >= 0xc0, so the packet is
being treated as audio/video.  It doesn't know how to deal with the
substream number for the private stream we are seeing, so it ignores
everything else, but it does use the SCR value, which is bogus in this case.

I do not know if the intention was to include the VOB extension packets in
this case or not.  Any thoughts?  If not, the code should be just checking
the stream ID, not the stream ID/substream ID combination.

Chris Rath

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