[theora] Ogg/theora a/v sync issue with liboggplay

xiphmont at xiph.org xiphmont at xiph.org
Fri Apr 2 02:39:16 PDT 2010

> Is the stream bad, or is liboggplay doing incorrect a/v sync?

It appears that audio is substantially leading video in the stream.
Although both are timestamped, this isn't strictly correct behavior; a
stream is supposed to be multiplexed in time order.  I'm guessing that
liboggplay is simply assuming correct time multiplexing and assuming
that each stream's start offset is to be corrected to a time of zero.

So... there's a bug in both.

Many live television streams start out as MPEG2, and MPEG2 can have a
substantial A/V offset; whatever is doing the encoding is not
accounting for it, and so the stream multiplex is way out of sync.

BUT A decoder that is working properly should still account for that
because it has the timestamps.  It will have to buffer way more data
then normal to cope, but it should still be capable of sync.


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