[mythtv] 'WriteAudio: buffer underrun' during playback caused by the scheduler

Mark Buechler mark.buechler at gmail.com
Sun Sep 10 14:03:43 UTC 2006


What's happening is mysql is taking more CPU/IO during the scheduling
process which takes CPU/IO away from playback/recording. I've had trouble
with this from time to time due to another issue but a temporary solution
would be to put your database on another (maybe faster) system. Another
might be to change the sql in the scheduling thread to use a loop and the
LIMIT clause to attemt to tone it down a bit.

- Mark.

On 9/9/06, Brian C. Huffman <bhuffman at graze.net> wrote:
>
> I'm getting similar problems during playback.  I don't think it's caused
> by the scheduler though...I'm seeing it on playing videos that have been
> ripped from DVD.  I'm about to open a ticket.
>
> -b
>
> On Sat, 2006-09-09 at 17:21 +0200, Jan Kleinig wrote:
> > Hi,
> >
> > I'm still having those problems :(
> >
> > I am using Knoppmyth R5C7 with mythtv svn 11084 and the ac3-patch 0.20
> > written by Mark Spieth.
> >
> > I'm using the EIT Scanner because tvtoday doesn't support that many
> > channels and I hate hunting for a new script when they change the
> > layout of there homepage...
> >
> > The problem is, that every time when the scheduler 'reschedules', I
> > get audio problems in the recording or LiveTV I watch.
> >
> > The backend log says:
> >
> > 2006-09-09 17:11:26.371 EITScanner: Added 10 EIT Events
> > 2006-09-09 17:11:26.375 Reschedule requested for id -1.
> > 2006-09-09 17:11:28.878 Scheduled 36 items in 2.5 = 1.19 match + 1.31
> > place
> >
> > At the same time, the playback stumbles and the audio is gone in most
> > of the cases. Sometimes, the audio comes back to live again after
> > about 3 seconds... The frontend tells me this:
> >
> > 2006-09-09 17:10:48.608 TV: Attempting to change from None to
> > WatchingPreRecorded
> > 2006-09-09 17:10:48.627 libavformat type mpegts
> > 0: start_time: 2615.887 duration: 539.622
> > 1: start_time: 2615.963 duration: 539.611
> > 2: start_time: 2615.896 duration: 539.616
> > stream: start_time: 29065.414 duration: 5996.522 bitrate=2668 kb/s
> > 2006-09-09 17:10:48.635 AFD: Opened codec 0x8bc9330, id(MPEG2VIDEO)
> > type(Video)
> > 2006-09-09 17:10:48.635 AFD: Setting maxchannels to 6, -1
> > 2006-09-09 17:10:48.635 AVFD: codec MP3 has 2 channels
> > 2006-09-09 17:10:48.635 AFD: Opened codec 0x8b52c10, id(MP3)
> > type(Audio)
> > 2006-09-09 17:10:48.826 Opening audio device 'default'. ch 2 sr 48000
> > 2006-09-09 17:10:48.826 Opening ALSA audio device 'default'.
> > 2006-09-09 17:10:49.005 VideoOutputXv: XvMCTex: Init failed
> > 2006-09-09 17:10:49.005 VideoOutputXv: XVideo Adaptor Name: 'ATI
> > Radeon Video Overlay'
> > 2006-09-09 17:10:49.398 TV: Changing from None to WatchingPreRecorded
> > 2006-09-09 17:10:49.399 Using realtime priority.
> > 2006-09-09 17:10:49.430 Video timing method: USleep with busy wait
> > 2006-09-09 17:11:26.752 WriteAudio: buffer underrun
> > 2006-09-09 17:11:27.247 WriteAudio: buffer underrun
> > 2006-09-09 17:11:27.521 WriteAudio: buffer underrun
> > 2006-09-09 17:11:27.776 WriteAudio: buffer underrun
> > 2006-09-09 17:11:28.339 WriteAudio: buffer underrun
> >
> > You see, at 17:11:26.375 the rescheduling is getting startet and at
> > that time, the error occures...
> >
> > Does anybody have an idea what to do?
> >
> > Thanks!
> > _______________________________________________
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> > mythtv-dev at mythtv.org
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>
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