[mythtv-users] Audio buffer underruns

[Victor Brunini]

Hi all,

I have a combined backend/frontend system that I've been using without any
issues for ~1 year now. Starting in the middle of this week I am suddenly
getting constant audio buffer underruns when trying to play any video in
mythtv. Thus far I have tried/tested:

1) Set /proc/asound/card0/pcm1p/sub0/prealloc to it's maximum value of
32768.
2) Tried both AC3 passthrough and standard PCM output in mythtv without
success. With PCM the audio is constantly stuttering. With AC3 passthrough
I get a brief (~1s) period of sound and after that see the receiver
constantly switching in and out of Dolby Digital mode due to the buffer
underruns.
3) Confirmed that mplayer and VLC both play the same video files with
either PCM or AC3 passthrough without any issues.
4) Confirmed that if I set the mythtv audio output device to NULL video
playback is very smooth and CPU usage is minimal (I'm using VDPAU for video
decoding).
5) Tried updating to the latest v0.27.3-152-g926bb8d fixes version
available on the mythbuntu repositories (prior to the issues I had disabled
automatic updates).

A section of the log file generated running with -v audio is available at
http://pastebin.com/J5wZgTYN

I'd appreciate any suggestions.

Thanks,
Victor
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