[mythtv-users] HD performance problems

[Tom Lichti]

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