[mythtv-users] High-Definition Playback performance data

Pete pete at putzin.net
Wed Apr 6 03:58:54 UTC 2005

Brad Templeton wrote:

>On Sun, Apr 03, 2005 at 08:51:50PM -0500, Pete wrote:
>>I'd like to know what I can do get that kind of performance. I've got an 
>>Athlon XP 3000 (512 MB RAM) and an FX 5200 (AGP) running myth .17 and 
>>FC3 (everything is from atrpms) where HD is close, but not quite. After 
>>a lot of hacking to get the channels to work, it finally comes up, but 
>>I'm getting lousy performance, with a lot of audio buffer underrun's 
>>(using spdif through an on board nvidia audio chip) and video stutter's. 
>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.
>mythtv-users mailing list
>mythtv-users at mythtv.org
Well, two things helped out quite a lot.
1. turning of libmpeg for playing back HDTV.
2. Geting AGP running. I hadn't checked, but it turns out the NvAGP 1 
was interfering with the kernel AGPGART (dumb mistake). I'm actually 
running with the atrpms kernel, but I figure with some of the changes 
coming in 2.6.12 (improvements to my SATA controller and whatnot) I'll 
just build my own and remove agpgart and let nvidia do it. I have seen 
pro's and cons on this, but the majority of the info is that the latest 
drivers tend to benefit from using nvidia's agp handler.

Right now, I can play back the pbs HD feed (which is 1080i) with no 
deint at between 90 and 100%. Other shows in 720p are right around 90%, 
and can go less, but there are a lot of jumps, and it's still not quite 
exactly good enough. Can't really do anything interesting though as it 
causes stutters in almost all the tests. SD playback is roughly 35% 
(still no deint), and it's all through the 5200 which is the final 
config as that will plug into my TV directly via a component adapter. 
But still, not at the magic < 80% that I'm shooting for. I fixed up the 
rtc bit a while ago for mplayer when this was my main desktop, and it's 
a combo FE/BE so network isn't a problem.

Future tests.
1. Get the nvidia driver from atrpms and try to pair all this up so I 
can try XvMC and see if that works out. Xv is nice, but it's not enough 
just yet.
2. Try out the nvidia agpgart.

All the other settings are done (realtime, deint off, opengl should be 
right, rtc set to 1024, etc), so are there any other suggestions? I'm close.

More information about the mythtv-users mailing list