[mythtv] MPEG2: Picture start, but no GOP

Jason Hoos jhoos at thwack.net
Fri Jul 9 13:16:51 EDT 2004

> In trying to diagnose the problem, it looks to me like there is NEVER a 
> GOP start indicator.  It looks like it does occationally see  a "Picture 
> Start" indicator.  The notes at the top of hdtvrecorder.cpp indicate 
> that Jason Hoos set it up such that a "Picture Start" indicator is "good 
> enough", but it does not seem to work for my UPN/WB stations.
> Jason, if you are still on this list, can you give me some  guidance on 
> what to look for?

I'm still around, although my time has been a bit limited. :(

What I remember of this off the top of my head (and it has probably since
been modified by Doug or Daniel), was that I made changes to the code that
looked for the GOP frame so that if it didn't find a GOP within a certain
amount of time, it would start using Picture Start indicators instead.  

Looking through past mail, I recall that method survived for a while, and
then mutated into a better method that looked for "Sequence Header Starts"
instead.  Look for messages in the archives with the subject "better GOP
detection for HDTV" to follow how things evolved.

Meanwhile, I'm in the process of finally rebuilding my Myth box and diving
back into some of this stuff soon...


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