[mythtv-users] HD performance problems

[Allan Wilson]

On 11/20/06, Tom Lichti <tom at redpepperracing.com> wrote:
>
> Steven Adeff wrote:
> > On 11/20/06, David Watkins <watkinshome at gmail.com> wrote:
> >> On 20/11/06, Shawn Rutledge <shawn.t.rutledge at gmail.com> wrote:
> >>> I have an Athlon 64 2400+, have been using it with a Hauppauge WinTV
> >>> card for a while, and just got a pchdtv HD-5500 card to see if I can
> >>> get some HD video.  Unfortunately due to the projector I'm using
> >>> currently the video has to be at 640x480 so I'm not getting the full
> >>> benefit of it until I get a better projector... I have kernel 2.6.18
> >>> and attempting to use the DVB drivers that come with it.  Installed an
> >>> antenna this afternoon, scanned the channels, receiving the signals
> >>> fine... but my system can't keep up.  There are a lot of dropped
> >>> frames (like I can see 4 or 5 frames in sequence every second or so,
> >>> then a pause, then more frames) and jerky audio.  I would think this
> >>> system should be fast enough.  I have an nvidia Geforce 5200 card with
> >>> nvidia drivers and enabled XvMC as described here
> >>>
> >>> http://www.mythtv.org/wiki/index.php/XvMC
> >>>
> >>> I switched to JFS on the partition that stores video files to get the
> >>> best possible filesystem performance.  hdparm -tT tells me I get 50
> >>> MB/sec transfer rates.  Tried various de-interlacing methods, and even
> >>> turning de-interlacing off altogether doesn't help.  Using Option
> >>> "NVAGP" "1".  'Use video as timebase' was off already.  Tried using
> >>> 'Seperate video modes for GUI and TV playback', no difference.
> >>>
> >>> I'm a little skeptical that /etc/X11/XvMCConfig is being read, since
> >>> there wasn't one installed already (it's a gentoo system BTW).
> >>>
> >>> What else could I be missing?
> >> Presumably you've already that checked XvMC is apparently working?
> >>
> >> 'XvMC found' type messages in the frontend log ( start the frontend
> >> from a terminal with)
> >>
> >> $> mythfrontend -v playback
> >>
> >> and the pop-up 'On screen display' (OSD) is in black and white.
> >>
> >> I had issues with my EPIA M1000 on standard definition.  XvMC was
> >> running but not giving me any CPU advantage (CPU load at 65% with or
> >> without XvMC).  Running the frontend as root reduced the load back to
> >> where I'd expect it (15%) and enabling realtime priority did the same
> >> when running as mythtv.
> >>
> >> I'm afraid I can't explain this,  but it worked for me.
> >
> > First, I would try disabling ALL options that pertain to how video is
> > displayed. Disable all deinterlacing, disable OpenGL vsync, etc. Then
> > go into nvidia-settings and disable all the xvideo options in there.
> >
> > Now try playing the HD file, and as David says, make sure XvMC is
> > being used. If you verify that it is, and your able to play back the
> > recording without hickups, I would then begin playing with Bob
> > deinterlacing and OpenGL sync in the MythTV TV Playback options.
> >
> > Keep the nvidia-settings sync options all turned off, they should not
> > be on as Myth has its own OpenGL sync option.
> >
> > also, search the list, lots of good information on this area.
> >
>
> Along with all that, I would check that your modeline is setup with the
> correct frequency for your area. NTSC requires a multiple of 30, when my
> system was using an unknown frequency (close to PAL I think) I got tons
> of prebuffer pauses, hiccups, etc, playing HD on a dual core P4 2.8GHz,
> which should have been more than capable of playing HD. When using XvMC,
> the mythfrontend log will show the average FPS of the display. If it's
> not running near your TV standard, you WILL get prebuffer pauses and
> audio/video sync problems. Mine was running at around 24 FPS average,
> and the playback was terrible. Once I got my modeline correct and it was
> running at 30 FPS (or very close to it, either 29.9 or 30.1) playback is
> perfect, even without XvMC. I actually have less CPU usage without XvMC
> than with it, and that is with BOB de-interlace on.
>
> For reference, my nVidia mode is the built-in '1024x768_60' with NO
> defined modelines in XF86Config-4 (or xorg.conf). PAL would probably
> want '1024x76_50'.
>
> HTH
>
> Tom
>
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This is a very interesting point and describes why my PIV 3.0 GHz system is
having such a hard time displaying HD. What do you mean by TV standard and
how do you tell the fps? I would love to check this out on my system and see
if it is the same thing.

Allan
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