[mythtv-users] Re: very serious A/V sync issues

[Matt S.]

I'm having a similar issue.  What happens is that I'll make a cutlist
based on the commercial detection.  Then, I'll transcode (although I'm
not sure it would matter if I didn't).  When I play the recording,
everything is great until I hit the cutlist.  The video directly after
the cut plays slow for about 2-3 seconds yet the audio doesn't.  Then
for 5-10 mins, the audio is about .5 to 1.5 seconds ahead of the
video, but somehow the video catches up.   This can be annoying to say
the least... could be related, I'm not sure.

Matt


On Mon, 7 Mar 2005 13:53:27 -0300, Robson Braga Araujo
<robson at akwan.com.br> wrote:
> On Mon, Mar 07, 2005 at 08:49:05AM -0500, Matt Vollmar wrote:
> > Sounds to me like the opengl_vsync issue.  You need to recompile Myth
> > without opengl_vsync set.  I don't think anyone has found a different
> > work-around.  I did this and everything was peachy.  It's worth a try,
> > anyway.  Search for it on the list if you aren't sure what this means.
> 
> Hi,
> 
> Regarding this issue, I posted the following mail in mythtv-dev:
> http://www.gossamer-threads.com/lists/mythtv/dev/116337
> 
> I got no answers. Since this seems to be a more active community, I'm
> hopping someone can comment on it. If you don't feel like opening a
> web browser, the message follows.
> 
> ------
> 
> Re: Playback problems with mythtv 0.17  [In reply to]
> On Fri, Mar 04, 2005 at 08:50:57PM -0300, Robson Braga Araujo wrote:
> > Hello,
> >
> > I'm having playback problems since I upgraded from 0.16 to 0.17. The
> > video plays too fast, gets ahead of the audio and generates tons of
> > prebuffering pause messages. I tried the latest cvs version, but no
> > luck. This happens if I'm watching live TV or any prerecorded show (no
> > prebuffering pauses here, obviously).
> >
> > I have a PVR-250. I tested with the drivers 0.1.9 and 0.3.2f. I'm also
> > using a SB Live! and a nvidia GeForce2 MX/MX 400 with the latest
> > drivers.
> >
> > I ran 0.16 (which plays fine) and 0.17 with -v all and generated too log
> > files for comparison. They are here:
> >
> > http://valfenda.cjb.net/~robson/log.0.16
> > http://valfenda.cjb.net/~robson/log.0.17
> >
> > Do you need any more information?
> > Thanks for any help.
> 
> After a good saturday trying different CVS versions to see when the bug
> appeared, I discovered that it is in the method
> OpenGLVideoSync::WaitForFrame in libs/libmythtv/vsync.cpp.
> 
> If I use another sync method like RTCVideoSync or BusyWaitVideoSync
> everything works fine.
> 
> The change that introduced the bug appeared between 2004-09-25 and
> 2004-09-26. The OpenGLVideoSync::WaitForFrame used to have a loop that
> did not exit until m_delay was less than or equal 0. It was substituted
> by two ifs that I'm guessing should do the same thing but they don't.
> 
> I tried reverting the OpenGLVideoSync::WaitForFrame method to the old
> version in the current CVS and now everything is working. The attached
> patch changes the first if for a while and gets rid of the second if
> because it would never be entered this way.
> 
> Is it the right way to do it?
> 
> --
> []s,
> Robson Braga Araujo
> Ciencia da Computacao - UFMG      http://www.dcc.ufmg.br/
> Akwan Information Technologies    http://www.akwan.com.br/
> 
>   Hobbes : Well, you still have afternoons and weekends
>   Calvin : That's when I watch TV.
> 
> 
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> 
> 
>