[mythtv-users] XvMC WriteAudio: buffer underrun -- partial solution

Dylan Semler dylan.semler at gmail.com
Sat Sep 30 17:19:03 UTC 2006

Many have been complaining about the appearance of a new XvMC error
after upgrading to 0.20:

2006-09-30 16:06:19.902 WriteAudio: buffer underrun
2006-09-30 16:06:19.995 NVP: prebuffering pause
2006-09-30 16:06:20.346 WriteAudio: buffer underrun
2006-09-30 16:06:20.614 WriteAudio: buffer underrun
2006-09-30 16:06:21.002 WriteAudio: buffer underrun

While I'm not sure if I had these problems in 0.19, I've been able to
get almost perfect XvMC playback by changing the NVAGP setting to "2"
in my xorg.conf:

Section "Device"
        Identifier  "Videocard0"
        Driver      "nvidia"
        Option      "NVAGP" "2"
        Option      "XvmcUsesTextures" "1"

I'm not sure if XvmcUsersTextures makes a difference, but changing the
NVAGP from 1 to 2 significantly increased performance.  I still get
short runs of prebuffering pauses lasting a few seconds every 15-20
seconds, but pretty much all of the audio errors are gone and now I'd
say playback is at least barely watchable (whereas with mplayer,
playback with xvmc is perfect).

The XvMC wiki page suggests using NVAGP 1, so if a few more people see
improvements, maybe we should change this.

If any of you have good memories, I still am having significant
picture deterioration in liveTV due to some sort of conflict with my
graphics card (GeForce 6200) and my HD-3000.  This does seem to be
improved somewhat by the new nvagp setting, although that may be just
in my head.


Type faster.  Use Dvorak:

More information about the mythtv-users mailing list