[mythtv-users] Problem with jerky playback/slow framerate

Erland Isaksson erland_i at hotmail.com
Tue Aug 22 05:39:23 UTC 2006


I sometimes get jerky playback on my new MythTV HTPC.

I am using the Nvidia driver(8762) and Ubuntu Dapper 6.06 (32 bit).
The CPU is a AMD 64 3500+ the graphic card a Nvidia 7300GT and !GB 
memory, the MythTV version is the SVN version from a week back.
The TV is a standard CRT connected to the TV-out on the Nvidia card 
using S-video.

One thing I noted was that the CPU usage seemed a little strange:
XvMC + Bob = 80% CPU
XvMC = 60% CPU
Standard = 15% CPU
Standard + Bob = 15%  CPU (Xorg 90% of the 15%)

The XvMC both with and without Bob works best(least jerky) but I get the 
highest CPU usage.
With Standard software decoder the CPU usage are pretty low but the 
picture is also more jerky than with XvMC.

I am not sure jerky is the right word, what happens is that the 
framerate seems to go down to about half the normal framerate sometimes 
for a minute and two. The CPU usage when the framerate goes down is the 
same, so the CPU does not seemt to be running at 100% when the framrate 
slows down.

One thing that seems a bit strange is that I thought the XvMC 
configuration should result in less CPU usage ?
I get the gray very flickering OSD when using XvMC so I think its really 
using XvMC.

I am just playing standard recordings from standard DVB-C (non HD).

I'll post some Xorg and mythtv log/configuration files here:

Any help or ideas for solutions or things to check are greatly appreciated


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