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what is a : WriteAudio: buffer underrun?

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mylists at wilsononline

Nov 25, 2009, 2:15 AM

Post #1 of 7 (694 views)
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what is a : WriteAudio: buffer underrun?

I'm getting alot of these during playback along with some pauses , can
someone explain to me what the cause of these are?
is it a Audio problem or Video problem?

2009-11-25 20:47:48.049 WriteAudio: buffer underrun
2009-11-25 20:49:24.993 WriteAudio: buffer underrun
2009-11-25 20:58:54.003 WriteAudio: buffer underrun
2009-11-25 20:58:54.984 WriteAudio: buffer underrun
2009-11-25 21:01:18.016 WriteAudio: buffer underrun

Paul
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warjamy at yahoo

Nov 25, 2009, 5:42 AM

Post #2 of 7 (665 views)
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Re: what is a : WriteAudio: buffer underrun? [In reply to]

not sure in the context of mythtv but a buffer underrun means that the audio app did not fill up the buffer fast enough before it was delivered to the audio driver. So you get some audio dropouts.

J.

--- On Wed, 11/25/09, Paul <mylists [at] wilsononline> wrote:

> From: Paul <mylists [at] wilsononline>
> Subject: [mythtv-users] what is a : WriteAudio: buffer underrun?
> To: "mythtv-users" <mythtv-users [at] mythtv>
> Date: Wednesday, November 25, 2009, 5:15 AM
> I'm getting alot of these during
> playback along with some pauses , can someone explain to me
> what the cause of these are?
> is it a Audio problem or Video problem?
>
> 2009-11-25 20:47:48.049 WriteAudio: buffer underrun
> 2009-11-25 20:49:24.993 WriteAudio: buffer underrun
> 2009-11-25 20:58:54.003 WriteAudio: buffer underrun
> 2009-11-25 20:58:54.984 WriteAudio: buffer underrun
> 2009-11-25 21:01:18.016 WriteAudio: buffer underrun
>
>
> Paul
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>

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eric at lisaneric

Nov 25, 2009, 6:51 AM

Post #3 of 7 (665 views)
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Re: what is a : WriteAudio: buffer underrun? [In reply to]

On Wed, Nov 25, 2009 at 5:15 AM, Paul <mylists [at] wilsononline> wrote:
> I'm getting alot of these during playback along with some pauses , can
> someone explain to me what the cause of these are?
> is it a Audio problem or Video problem?
>
> 2009-11-25 20:47:48.049 WriteAudio: buffer underrun

It's usually a resource problem. If there's some bottle neck that's
preventing the video from being decoded in real time, the sound card
can run out of data to play and you'll get one of these messages. It
could be that you don't have enough CPU to decode the video you're
trying to play, along with whatever else your system is trying to do
at the same time.

Eric
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mylists at wilsononline

Nov 27, 2009, 9:57 PM

Post #4 of 7 (616 views)
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Re: what is a : WriteAudio: buffer underrun? [In reply to]

mtdean at thirdcontact

Nov 27, 2009, 10:49 PM

Post #5 of 7 (616 views)
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Re: what is a : WriteAudio: buffer underrun? [In reply to]

On 11/28/2009 12:57 AM, Paul wrote:
> I have a AMD 3200 so I'm pretty sure this has enough grunt to playback
> SD video..
> it must be some other resource issue, but how do I exactly find out?

http://www.mythtv.org/wiki/Troubleshooting:Prebuffering_pause

especially

http://www.mythtv.org/wiki/Troubleshooting:Prebuffering_pause#Audio_Issues

(but others may still be important).

Mike
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mylists at wilsononline

Nov 28, 2009, 10:40 PM

Post #6 of 7 (577 views)
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Re: what is a : WriteAudio: buffer underrun? [In reply to]

On 25/11/2009 9:15 PM, Paul wrote:
> I'm getting alot of these during playback along with some pauses , can
> someone explain to me what the cause of these are?
> is it a Audio problem or Video problem?
>
> 2009-11-25 20:47:48.049 WriteAudio: buffer underrun
> 2009-11-25 20:49:24.993 WriteAudio: buffer underrun
> 2009-11-25 20:58:54.003 WriteAudio: buffer underrun
> 2009-11-25 20:58:54.984 WriteAudio: buffer underrun
> 2009-11-25 21:01:18.016 WriteAudio: buffer underrun
>
>
> Paul
>

I turned on frontend playback debug
note I'm using VDPAU normal profile
I now have a 8500 GT with 1GB ram surely this is fast enough for this video
and these are the messages that seem to relate to the underrun:

'video_output' mean = '39995.59', std. dev. = '161.42', fps = '25.00'
2009-11-29 17:29:24.986 WriteAudio: buffer underrun
2009-11-29 17:29:25.034 NVP(0): Video is 3.86602 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 4.6745 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 5.03088 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 5.04815 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 4.8111 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 4.38333 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 3.81247 frames behind audio (too slow), dropping
frame to catch up.
2009-11-29 17:29:25.034 NVP(0): Video is 3.1406 frames behind audio (too slow), dropping
frame to catch up.
'video_output' mean = '52594.58', std. dev. = '162213.41', fps = '19.01'
2

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belcampo at zonnet

Nov 29, 2009, 3:48 AM

Post #7 of 7 (573 views)
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Re: what is a : WriteAudio: buffer underrun? [In reply to]

Paul wrote:
> On 25/11/2009 9:15 PM, Paul wrote:
>> I'm getting alot of these during playback along with some pauses , can
>> someone explain to me what the cause of these are?
>> is it a Audio problem or Video problem?
>>
>> 2009-11-25 20:47:48.049 WriteAudio: buffer underrun
>> 2009-11-25 20:49:24.993 WriteAudio: buffer underrun
>> 2009-11-25 20:58:54.003 WriteAudio: buffer underrun
>> 2009-11-25 20:58:54.984 WriteAudio: buffer underrun
>> 2009-11-25 21:01:18.016 WriteAudio: buffer underrun
>>
>>
>> Paul
>>
>
> I turned on frontend playback debug
> note I'm using VDPAU normal profile
> I now have a 8500 GT with 1GB ram surely this is fast enough for this video
> and these are the messages that seem to relate to the underrun:
>
>
> 'video_output' mean = '39995.59', std. dev. = '161.42', fps = '25.00'
> 2009-11-29 17:29:24.986 WriteAudio: buffer underrun
> 2009-11-29 17:29:25.034 NVP(0): Video is 3.86602 frames behind audio
> (too slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 4.6745 frames behind audio (too
> slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 5.03088 frames behind audio
> (too slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 5.04815 frames behind audio
> (too slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 4.8111 frames behind audio (too
> slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 4.38333 frames behind audio
> (too slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 3.81247 frames behind audio
> (too slow), dropping frame to catch up.
> 2009-11-29 17:29:25.034 NVP(0): Video is 3.1406 frames behind audio (too
> slow), dropping frame to catch up.
> 'video_output' mean = '52594.58', std. dev. = '162213.41', fps = '19.01'
> 2
I know nothing about VDPAU, but it seems it doesn't work as it's
configured now, because you only get 19.01fps instead of 25fps
>
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

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