[mythtv-users] 0.19, XvMC, and Prebuffer pause

Joe Silver devils.taco at gmail.com
Sun Mar 19 01:22:44 UTC 2006


>
> On 2/25/06, Joe Silver <devils.taco at gmail.com> wrote:
> >
> > So it looks like there has been a trouble ticket opened on this issue:
> > http://svn.mythtv.org/trac/ticket/1361
> > http://www.gossamer-threads.com/lists/mythtv/commits/185733
> >
> > However, it doesn't really look like it's being investigated further.  I
> > could be mistaken, but it sounds like this is being passed off as a
> > performance issue instead of an internal issue.  Hopefully one of the
> > developers has the same issue and can provide the appropriate performance
> > settings to the rest of us to correct this issue.  It sounds like the rest
> > of us are stumped!  Perhaps it's something to do with differences between
> > default settings between 0.18 and 0.19.  Why these defaults would be
> > changed to break something as important as HD playback is a real mystery...
> >
> > -Joe
> >
>
>
> I'm screwing around some more with this issue... no useable workaround
> yet, but I have discovered that xine will playback the captured livetv
> streams perfectly with xvmc and deinterlacing disabled... the hd captures
> look fabulous.  i'm now ready to claim XVMC playback is broken in mythtv's
> internal player.  probably not a huge surprise, but I am surprised that it
> works in one and not the other.  the only viable workaround i can come up
> with is to buy a faster processor so i don't need XVMC.  I'm a little
> nervous that it wont actually fix the problem (is it really XVMC or the
> internal player???), but to buy one and try it is the only way to test this
> out.  Anyone out there with a fast cpu and nvidia card (FX5200) playing HD
> captures to test this theory out for me?  Does enabling XVMC cause audio
> stuttering (prebuffering pause and buffer underruns)??
>
> Cheers,
> JS
>


PARTIALLY SOLVED!  For me at least.  I was inspired by the recent posts
about
Option      "XvmcUsesTextures"  "True/False"

and was curious what would happen if i changed this.

For all my previous testing, this option was missing from my xorg.conf.  I
enabled it (ie True) and it made the OSD turn greyscale, but it has solved
the problems of buffer underruns while watching recorded and live tv (SD and
HDTV) captured from my HD3000 operating in QAM 256 mode.

This isn't consistently true, however.  If I am watching livetv and I use
the browse mode to change channels the newly selected channel usually comes
up fine, but if I manually type in the channel number almost always nothing
good happens.  Sometimes I get terrible jitter (audio and video), other
times I get a black screen that hangs until i exit live tv with TONS of
prebuffering pause messages.  but it looks like i am going to be able to
playback recorded HDTV most of the time, which is all that really matters to
me.

JS
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