[mythtv-users] Performance issue on 0.24-fixes - Playback stalls when a recording starts/ends

[Johnny Walker]

On Wed, Mar 16, 2011 at 11:56 AM, Martin Andersen <ma2010.list at gmail.com> wrote:
> Hi list
>
> I've just upgraded from 0.23 to 0.24-fixes, but I'm having problems with
> playback which I didn't have on 0.23. Playback often pauses for a second or
> two - apparently when a recording start or stop.
>
> I have a fairly capable Core i5 as a backend and a ION-based frontend on a
> gigabit network. The backend log doesn't give any errors and the frontend
> gives me:
> 2011-03-16 17:06:03.446 VDPAU: Added 2 output surfaces (total 4, max 4)
> 2011-03-16 17:30:01.611 ALSA, Error: WriteAudio: buffer underrun
> 2011-03-16 17:30:01.881 Player(1): Waited 100ms for video buffers
> AAAAAAAAAAAAAaALL
> 2011-03-16 17:30:01.887 Player(1): Waited 100ms for video buffers
> AAAAAAAAAAAAAaALL
> 2011-03-16 17:30:01.898 Player(1): Waited 100ms for video buffers
> AAAAAAAAAAAAAaALL
> 2011-03-16 17:30:01.903 Player(1): Waited 100ms for video buffers
> AAAAAAAAAAAAAaALL
> 2011-03-16 17:30:02.008 Player(1): Waited 100ms for video buffers
> AAAAAAAAAAAAAaALL
> 2011-03-16 17:30:02.024 Player(1): Waited 100ms for video buffers
> AAAAAAAAAAAAAaALL
> 2011-03-16 17:30:02.666
> RingBuf(myth://192.168.1.10:6543/1000_20110316173000.mpg) Warning: Not
> starting read ahead thread, already running
> 2011-03-16 17:30:02.694 Player(1): Forcing decode extra audio option on
> (Video method requires it).
> 2011-03-16 17:30:02.775 AFD Warning: ScanATSCCaptionStreams() called with no
> PMT
> 2011-03-16 17:30:02.775 AFD: Opened codec 0x7fee30e62c30, id(MPEG2VIDEO)
> type(Video)
> 2011-03-16 17:30:02.775 AFD: codec MP2 has 2 channels
> 2011-03-16 17:30:02.775 AFD: Opened codec 0x7fee3009def0, id(MP2)
> type(Audio)
> 2011-03-16 17:30:02.799 AFD: Resetting byte context eof (livetv 1 was eof 0)
> 2011-03-16 17:30:02.889 [mpegvideo_vdpau @ 0x7fee57f515a0]warning: first
> frame is no keyframe
> 2011-03-16 17:30:03.032 [mpegvideo_vdpau @ 0x7fee57f515a0]warning: first
> frame is no keyframe
>
> MythTV Version   : v0.24-211-g785ea1b
> MythTV Branch    : fixes/0.24
> Network Protocol : 63
> Library API      : 0.24.20101129-1
> QT Version       : 4.6.2
>
> I've tried to search the list, and it seems like quite a few users are
> affected by the issue:
> http://www.gossamer-threads.com/lists/mythtv/users/474214#474214
>
> Does a bug report exist or has anyone identified/fixed the issue?
>
> Does anyone know if the issue is the same in trunk?
>
> Thanks
>

I noticed this:

2011-03-16 17:30:02.666
RingBuf(myth://192.168.1.10:6543/1000_20110316173000.mpg) Warning: Not
starting read ahead thread, already running

You can also use NFS mounts of your Storage Groups directories so that
the physical paths are the same on the Frontend as the Backend and it
increases performance. At least it does for my ION frontend with
Triple Core backend. I believe the newer code will also autodetect if
this has been done and not use myth:// streaming from the backend if
it doesn't need it.

Also how much RAM is allocated to the ION chip? What sound device are
you using and is it configured correctly?

-Johnny