[mythtv] Ticket #7964: Predictively skip frames to smooth out timestretch

[David Engel]

On Mon, May 10, 2010 at 08:00:15AM +1000, Mark Spieth wrote:
> >Are there any known reasons why your patch won't work with 0.23-fixes,
> >other than having to manually apply some parts?  v5 worked fine on
> >1080i, and on 720p at normal speed.  It didn't work very well on 720p,
> >however, when timestretch was used.  After a skip, the video would
> >stop updating and it could never resync until timestretch was turned
> >off.
> >
> not that I know of.
> what is your refresh rate and source frame rate and vsync mode?
> vdpau or not? 6 ch or 2 ch or digitalout?

This was with an atsc mpeg2 1280x720x60 (really 59.94 fps) recording 
played on a 1920x1080x60 display using vdpau and rtc timing.  The 
audio was 2-channel AC3 played over HDMI. 

> I suspect frameinterval < refreshinterval for your case and I wasnt
> able to test that scenario. john tested and apparently was ok.
> have you tested on trunk? if so can you provide a small segment of
> such a recording?
> or if it works ok on trunk then you will have to run with
> playback,audio,timestamp with a couple of extra logs enabled in
> AVSync (#if) and vsync.cpp (#define GLVSYNCDEBUG) and do a short run
> and send me the logs.

OK.  It'll be at least tomorrow before I can do any more testing.


On Sun, May 09, 2010 at 04:08:25PM -0600, John P Poet wrote:
> I finally upgrading to version 5 of Mark's patch and also notice that
> skipping around in a video causes issues.  General playback (with
> timestretch) is fine, but it can take several seconds for playback to
> become smooth again after a skip -- If there is a ticker-tape on the
> screen, it will be a bit jerky for a few seconds before smoothing out
> again.

That sounds like the same problem.

David
-- 
David Engel
david at istwok.net