Hi Daniel, well when the CPU is at 60% the playback is fine.
There is something that triggers the playback to hit 95% and then its awfull... I might add up until a week ago 1080i playback was fine and I never had any stuttering problems (other than seeking of course) On the Nvidia thing what exactly do we need to say to them... I dont mind emailing their support and asking them to increase the XvMC buffer size... i would have thought this would be pretty easy todo??? Cheers Dave > On Sat, 2005-05-14 at 22:07 +0800, David Shirley wrote: >> hey daniel, >> >> i did some more diagnosis... this is with today's CVS... >> >> I found that when watching 1080i TV the CPU will sit at 30% for credits >> (ie mostly black screen), and 50-60% for normal TV. > > This is pretty high, I'm thinking maybe the Athlon XP @ 2Ghz isn't > up to decoding 1080i with 8 buffers, even with XvMC. The only thing > I can suggest is try enabling real-time threads by setting the suid > bit on the MythFrontend executable. > > The problem his that while it is "only" eating up 60% of your CPU > MythTV needs the CPU in a bursty fashion in order to get frames > queued up and displayed in time. > > Having eight XvMC buffers really means you only have two free buffers > in the worst case scenario. Two for OSD, three for I/P-frame past/future > frames, one for display, and _two_ for filling. If there is a lot > of motion or some other process is sucking up the CPU when one of > those two frames becomes available, then you get problems... And > this "worst case scenario" happens all the time with XvMC. You > have basically 1/30th of a second (@720p), to fill two buffers, > and you must do it at a rate of 1 buffer every 1/60th of a second. > Which means you are really using the fancy soft real-time features > of the 2.6 kernel just to keep up. This means you can't have any > non-preemptable drivers, your APIC interrupt situation has to > be happy, your hard-drive DMA access must be working properly, > and your driver must unmask interrupts (hdparm -u). It's just to > much to expect to go right. > > I'm hoping that if enough people complain to nVidia about their > XvMC implementation only having eight buffers they will fix this > in a future driver... The VIA Unichrome drivers support twice as > many buffers! > > -- Daniel > > > > > !DSPAM:4286730b208535847718184! > > _______________________________________________ mythtv-dev mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
