[mythtv-users] Re: High-Definition Playback performance data

[SpikeyGG]

>We should try to build a list of all the things that can go wrong in
>making HD work smoothly.  There are many.
>
>They include:
>
>
>    a) Right drivers for card with your kernel
>    b) Proper AGP bus speed and AGP interface driver in use
>    c) Proper user of openGL sync for retrace
>    d) Proper settings for deinterlace and, if used, xvmc
>    e) Proper sound settings and handling of 5.1 sound and multiple streams
>    f) Real time scheduling of playback thread
>    g) Making sure disk or network speed is adequate
>    h) Nothing else sucking up CPU on the machine
>
>And of course having the right cards and memory itself.
>

I found a couple of things this weekend while screwing around with my 
machine.

1.  Getting the RTC working correctly.  I couldn't find it documented 
anywhere but when I ran "mythfrontend -v all" and went through all the 
output I noticed that it was falling back on a different method for syncing 
because something was not right with the RTC (also, I noticed that mplayer 
was saying stuff about can't use the RTC).  Anyway, I did some googling and 
found that if you enable the HPET in your kernel it'll conflict with the 
RTC.  I recompiled without it and behold both programs use the RTC now! 
I've noticed an improvement in audio-video sync.

2.  Forcing the nvidia drivers to use the NvAGP "1" value.  I read that it 
improves performance so I stuck it in the XF86Config file but then I started 
getting those messages in syslog about "AGPGART is loaded can't use NvAGP". 
This is also due to compiling in the AGP support in the kernel.  I 
recompiled without it and behold glxgears gives me about 1000 more fps!

Anyway, I just thought I'd share since I was able to gain some quality and 
speed in those two areas.  As far as performance I get theses numbers:

Standard Definition Digital - Anywhere from 15% - 45% cpu
High Definition Digital - Anywhere from 65% - 100% cpu (always smooth)

I'm not using XvMC since there has been so much talk of hard lock ups and 
stuff I have been too scared to give it a try.

-Greg
--- Running Conditions ---
939pin Athlon64 3200+
OS - Standard Issue Debian (32-bit)
MythTV - CVS Version (4/3/2005)
Capture Card - pcHDTV HD-3000
Drivers - Using DVB (kernel 2.6.12)