[mythtv-users] My Perennial Problems with XvMC

Brad Fuller bradallenfuller at yahoo.com
Tue Sep 19 21:44:58 UTC 2006

Dylan Semler wrote:
> New developments:
> So I went to watch LiveTV yesterday on a different, remote frontend
> (ati card--no xvmc).  I was watching an SD channel and was getting the
> picture deterioration problem on that as well!  However, it wasn't
> like on the BE/FE machine as it only lasted a few seconds and occurred
> about once ever 30 seconds.  I chalked it up to the fact that the BE
> was running a comflag job and the processor couldn't keep up.  So I
> turned of the comflaging and went back to watching TV.  10 minutes
> later, the deteriorations happen again.  Same thing as before.. only
> ever 30 seconds or so and only lasting about second each.  And then it
> hits me.  This pattern corresponds exactly with when the screensaver
> is drawn on the BE monitors.  I had it set to the space scenes and
> every 30 seconds or so it draws a new image from space onto the
> screen.  Thinking back on it, as I was watching a football game last
> sunday on a remote frontend and browsing the web on the BE at the same
> time, every time I scrolled a web page or opened a new tab, I would
> get short distortions while the screen was changing.  The
> deteriorations seem to be recorded into the mpeg files, as watching
> the recordings again show the deteriorations happening at the same
> times.
> So it would seem the problem is when the pcHDTV is recording and the
> graphics card is drawing something on the screen, and the distortions
> exist in the recorded mpeg file.  Since this occurred with the GeForce
> 4200 and the 6200, it may be a problem with my HD-3000.  Or maybe a
> bus bandwidth problem?  I don't know.  I didn't see the deterioration
> when I was playing with myth last April, but I have moved the computer
> quite a bit since then.  Is it possible something broke on my tuner
> card?
> I guess it's not really an XvMC problem at all--which explains why
> mplayer was not having the same issues.
> By the way Norm, thanks anyways for taking the time to help me
> troubleshoot the XvMC step-by-step.  Thankfully we won't be having to
> scrutinize our way through all those options now.
> Cheers,
So, the thing to do is to turn off the  screen saver (for good) and see
if that _really_ changes the problem.
Because, I think it strange that problems are written into the file
because of a screen saver. There's not a lot of processing when
recording HD, right? Just copying the frames - no mpeg encoding going on.

(BTW, what does 4200/6200 issues have to do with the HD3000?)

brad fuller

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