[mythtv] race condition on playback

[Steven]

Hi,

Playing back recording with CVS from about 4 days ago.
Every couple (=2) of minutes mythplayback (mpeg2 recording) goes to max
processor load for a few seconds. Nothing shows up in either mythbackend
or frontend log. The result look like fast forwarding for a few seconds
and audio stops. Pressing pause/play fixes things. After 10 seconds
playback goes back to normal and mythfrontend goes back to about 30%
processorload.

>From frontend log :
----------
Using realtime priority.
Video timing method: USleep with busy wait
----------

Any tips on how to debug this? Would this show up if I do a backtrace?
verbose playback? 
Already played with different deinterlacing filters, extra audio
buffering and video as timebase but that doesn't seem to make a
difference. Extra audio buffering seem to make the effect less noticable
(shorter skip) but it is still there.

The same recordings play fine on another box with an older myth install.

Steven