[mythtv-users] Strange Playback behaviour

[Andy Smith]

On Tue, 9 Oct 2018 at 16:23, Andy Smith <hastymind at googlemail.com> wrote:
>
> On Tue, 9 Oct 2018 at 15:34, Peter Bennett <pb.mythtv at gmail.com> wrote:
> >
> > On 10/09/2018 08:39 AM, Andy Smith wrote:
> > > Oct  8 21:34:05 mustard mythfrontend.real: mythfrontend[18401]: E
> > > CoreContext vsync.cpp:358 (TryInit) VSYNC: RTCVideoSync: Could not
> > > open /dev/rtc: #012#011#011#011eno: Permission denied (13)
> > I don't think that is the cause of your problem. Look for messages in
> > the log that say frames are dropped to catch up or frame interval is
> > doubled to slow down.
>
> You are correct, not in the section of log I posted, but later on
> whilst watching another recording, there is plenty of this type of
> message (but none of the dropped frame messages) :-
>
> Oct  8 23:06:02 mustard mythfrontend.real: mythfrontend[18401]: I
> CoreContext mythplayer.cpp:2044 (AVSync) Player(3): Video is 3.42812
> frames ahead of audio,#012#011#011#011doubling video frame interval to
> slow down.
>
> Is it still worth trying the '-O AVSyncAveraging=60' option?
> Thanks

Testing one thing at a time :-

1) Try to manually increase audio buffer with: echo 128 | sudo tee
/proc/asound/card1/pcm7p/sub0/prealloc

made no difference to playback, but did eliminate messages in log.

2) Sorting out permissions (permanently) on /dev/rtc*

made no difference to playback, still getting permission denied errors
in log and still getting Video timing method: USleep with busy wait

3) Starting mythfrontend with AVSyncAveraging=60

That has sorted the playback with no detriment to lip sync that I have
noticed so far.

This has enabled me to try some of the other Video Playback Profiles
which were previously unuseable.  What is the strategy for choosing a
profile here?  None of them are really 'perfect', I've seen people
describing effects as 'tearing' and I guess that is what I am seeing -
it was the reason why I had originally planned to replace the GT218
[GeForce 210] but mostly now I have a platform that meets WAF
requirements, if not my own, so I might defer that, there has been a
lot of disruption over the last few weeks and I need to restore
confidence!

Thanks again for all the help BTW.
--
Andy