[mythtv] AVSync in master, Normal decoding, vga monitor and built-in audio analog stereo

Mark Kendall mark.kendall at gmail.com
Mon Dec 9 22:12:00 UTC 2019

On Mon, 9 Dec 2019 at 21:21, Gregorio Gervasio Jr.
<gregorio.gervasio at gmail.com> wrote:
> >>>>> John Pilkington writes:
> > Hi Mark, Peter, Tim et al...
> > I'm now running b5edda1b06e, today's master, under el7 with hardware
> > as in the subject.
> > A recording that allows good sensory evaluation of a/v sync shows
> > noticeable drift that is not evident from the -v playback log.
> [...]
>         At least for me, it seems like the sync problems (where audio
> runs ahead of video) are only happening with 1080i (MPEG-2) content and
> only when I use the double-rate software deinterlacers.  If I disable
> double-rate deinterlacing or if I enable "Prefer OpenGL deinterlacers",
> I don't see the problem.  I'll need to dig deeper into it to be sure,
> though ...


You may be on to something - I hadn't thought to look at the FFmpeg
deinterlacers. They manipulate timestamps when run at double rate and
as the filtering happens before the a/v sync - it could lead to drift
if there is any small loss in precision.

John - does that tie up with what you are seeing?

Thanks and regards

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