[mythtv-users] Mythtv 0.24 Acer Revo ALSA WriteAudio buffer underruns

[Dave Sp]

On Sun, Dec 26, 2010 at 12:23 PM, <pnetherwood at email.com> wrote:

> Hi
>
> Since upgrading to 0.24 my Acer R3600 Revo's have been stuttering on
> playback. It was all fine 0.23. It noticed in the logs it was mentioning
> failing to do a preview which always seemed to occur at the same time as the
> buffer underruns. Below is a snippet from my log:
>
> 2010-12-25 20:10:48.104 AO: Opening audio device 'hdmi:CARD=NVidia,DEV=0'
> ch 2(2) sr 48000 sf signed 16 bit reenc 0
> 2010-12-25 20:10:48.107 AudioPlayer: Enabling Audio
> 2010-12-25 20:10:49.555 VDPAU: Created 2 output surfaces.
> 2010-12-25 20:10:49.555 VDPAU: Version 1
> 2010-12-25 20:10:49.555 VDPAU: Information NVIDIA VDPAU Driver Shared
> Library  256.44  Thu Jul 29 01:59:12 PDT 2010
> 2010-12-25 20:10:49.555 VDPAU: Created VDPAU render device 1280x720
> 2010-12-25 20:10:49.737 Player(0): Forcing decode extra audio option on
> (Video method requires it).
> 2010-12-25 20:10:49.978 Player(0): Video timing method: USleep with busy
> wait
> 2010-12-25 20:10:49.979 TV: Changing from None to WatchingPreRecorded
> 2010-12-25 20:10:50.056 VDPAU: Added 2 output surfaces (total 4, max 4)
> 2010-12-25 20:10:50.183 ALSA, Error: WriteAudio: buffer underrun
> 2010-12-25 20:36:07.118 ALSA, Error: WriteAudio: buffer underrun
> 2010-12-25 20:36:07.914 ALSA, Error: WriteAudio: buffer underrun
> 2010-12-25 20:36:08.517 ALSA, Error: WriteAudio: buffer underrun
> 2010-12-25 20:36:09.644 PlaybackBox: Ignoring PREVIEW_SUCCESS, item no
> longer on screen.
> 2010-12-25 20:36:12.526 ALSA, Error: WriteAudio: buffer underrun
>
> Anyone know why its trying to do a preview in the middle of a playback? I
> did notice an old setting in my settings table relating to previews called
> "PlaybackPreview" which I set from 1 to 0 with no effect. Probably a relic
> from 0.21 when previews worked but with no effect.
>
> I also seem to get the problem when it appears to be waiting for video
> buffers:
>
> 2010-12-25 21:10:05.245 ALSA, Error: WriteAudio: buffer underrun
> 2010-12-25 21:10:05.427 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.438 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.444 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.454 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.558 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.564 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.580 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.684 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
> 2010-12-25 21:10:05.700 Player(0): Waited 100ms for video buffers
> AAAAAAdAAAADLLAAA
>
> Unfortunately -v audio didn't add any extra infor at teh time of the buffer
> underruns.
> I'm not sure if these are related or two separate problems. My ALSA device
> is: hdmi:CARD=NVidia,DEV=0. I have also tried using ALSA:default and
> changing the buffer size my .asoundrc file which didn't help much. I have
> also tried increasing by VDPAU buffer size to 32 in the filter settings with
> no effect. I'm using version fixes/0.24 [f3ddc58]. My alsa version is
> 1.0.22.1
>
> Any thoughts?
>
> Paul
>

I was able to get rid of the "WriteAudio: buffer underrun" problem by
enabling "Extra audio buffering" under "Utilities/Setup --> Setup --> TV
Settings --> Playback".  (It only happened while watching 720p HD, not
1080p, which was interesting.)

--Dave
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