[mythtv-users] Video studder XvMC w/OSD

[EJS]

On Sun, Mar 30, 2008 at 01:28:08PM -0500, Mitch Gore wrote: 
> Hi, 
> 
> On my frontend I have a bad issue with XvMC and HD video. When watching HD 
> and the OSD comes up I get very bad studdering. 

I am seeing the same symptoms, though for me, I am guessing that the cause is related 
to an AGP problem (not a cpu clock speed issue).  I have followed all of steps on the XvMC wiki page 
and spent the past few days playing around with different combinations of settings to see if I 
could fix the problem but I haven't had any luck. 
The reason I am suspecting AGP is that if I check the agp status, I see its disabled:
cat /proc/driver/nvidia/agp/status
Status:          Disabled
AGP initialization failed, please check the ouput
of the 'dmesg' command and/or your system log file
for additional information on this problem.
Of course dmesg, shows that AGPGART backend is loaded sucessfully, but this got me to thinking 
that perhaps this inconsistency is part of the problem. In following the XvMC wiki my xorg.conf is 
telling X to use the NVAGP kernel driver; whereas, Fedora is loading AGPGART. However, whenever I 
tried to resolve this conflict, either by consistently using AGPART (by changing xorg.conf to 
NVAGP "2") or  NVAGP (by leaving NVAGP "1" and adding the kernel parameter agp=off), the problem 
just gets worse in that now when I try to watch LiveTV dont see any picture at all!! Just a black 
sceen.
 
I dont see anything in particular standing out in the log files that would indicate what the 
problem is, but I can definitely tell myth is trying to use XvMC:
2008-05-19 16:58:27.175 VideoOutputXv: ProcessFrameXvMC: Tried to reuse frame but failed
2008-05-19 16:58:27.175 VideoOutputXv: ProcessFrameXvMC: Called without frame
2008-05-19 16:58:27.175 VideoOutputXv: ShowXvMC(): No frame to show
<snip...>
2008-05-19 16:58:27.199 XvMC: picture structure FRAME
The only difference between the two configurations is that in the "Disabled AGP" version, I see 
lots of:
2008-05-19 16:53:47.736 NVP: Waiting for prebuffer.. 0 dLDLAAAA
2008-05-19 16:53:47.798 NVP: prebuffering pause
And then a few lines like:
'video_output' mean = '62553.21', std. dev. = '15127.56', fps = '15.99'
Whereas in the "Enabled AGP" version, all I see is lots of:
2008-05-19 16:58:27.309 NVP: Waiting for prebuffer.. 2 LAAAAAAA
2008-05-19 16:58:27.443 NVP: Waiting for prebuffer.. 3 LAAAAAAA
2008-05-19 16:58:27.576 NVP: Waiting for prebuffer.. 4 LAAAAAAA
2008-05-19 16:58:27.709 NVP: Waiting for prebuffer.. 5 LAAAAAAA
2008-05-19 16:58:27.842 NVP: Waiting for prebuffer.. 6 LAAAAAAA
2008-05-19 16:58:27.975 NVP: Waiting for prebuffer.. 7 LAAAAAAA
2008-05-19 16:58:28.109 NVP: Waiting for prebuffer.. 8 LAAAAAAA
2008-05-19 16:58:28.242 NVP: Waiting for prebuffer.. 9 LAAAAAAA
2008-05-19 16:58:28.375 NVP: Prebuffer wait timed out 10 times.
Then I eventually have to kill mythfrontend. 
In either case I see a CPU load of about 60%, which spikes to about 92% when the OSD is up. I also 
noticed that the CPU load (60%/92%) is about the same when I dont use XvMC. In fact, without XvMC, 
I think the stuttering actually improves - although it is still pretty bad.
At this point, I've pretty much exhausted any ideas for next steps, so if there are any ideas, I'd 
greatly appreciate the help. 
Here are some of the relevant configs:
Intel(R) Pentium(R) 4 CPU 2.40GHz (cpu MHz: 2405.525)
Asus FX5200 AGP 8x 128Mg (350.0 MHz maximum pixel clock)
NVIDIA dlloader X Driver  169.12  (Livna Repo)
Fedora 8 ( 2.6.24.4-64.fc8)
MythTV Version   : 17023
MythTV Branch    : branches/release-0-21-fixes
Library API      : 0.21.20080304-1
Options compiled in:
 linux debug using_oss using_alsa using_arts using_backend using_dbox2 using_dvb using_frontend 
using_hdhomerun using_iptv using_ivtv using_joystick_menu using_lirc using_v4l using_x11 
using_xrandr using_xv using_xvmc using_xvmcw using_xvmc_vld using_bindings_perl 
using_bindings_python using_opengl using_ffmpeg_threads using_live
All driving an old 36" Zenith tv.
Thanks again,
J