[mythtv-users] glitchy audio with vdpau

[Alex Williamson]

I'm using an ASUS M3N78-VM with onboard audio, onboard Nvidia 8200 gfx
(512MB memory) and 4850e 2.5GHz dual core CPU.  I upgraded to Ubuntu
Jaunty and I'm using the Ubuntu ppa builds of mythtv trunk (currently
20250).

Initially I was really excited to try out vdpau and impressed that my
system can churn out HD via my hdromrun with hardly any CPU load.
Then I started to notice the audio glitches and the prebuffering
pauses in my mythfrontend log file.  My ultimate goal is to make use
of an hdpvr connected to my stb, but the output becomes unwatchable
with the audio glitching and the effect it seems to have on the
picture.  If I turn off audio, the video seems to be pretty good
(maybe not perfect, but a lot better).  I have yet to find a
combination of frontend settings that can play the H.264 output
cleanly (vdpau or not).  For hdhomerun content, I can use the
"standard" decoder with vdpau for both options and get smooth output,
but this hardly seems to be offloading anything to the gfx.  FWIW, I'm
using the 180.37 Nvidia release.  I've also tried an old emu10k
(SBLive) audio card, but it didn't make a difference.  With vdpau, the
CPU usage is low when I get the audio glitches, and the system is a
combined frontend/backend, so the data is local.  I didn't see
anything else in the wiki page on audio problems that seemed relevant
to this problem.  I'm using the analog stereo out from the system, so
no AC3 passthrough.

Any thoughts on what to try next?  I see reports of the 8200 IGP
working fine with vdpau, so I'm hoping it's not a problem there.  I've
tried overclocking the CPU to 3GHz and the gfx to 600MHz as a test,
but it didn't seem to improve anything.  Would using AC3 pass-through
with an HDMI output buy me anything?  Thanks for any pointers or
details of this class of system working with vdpau (or even software
decoding for H.264),

Alex