[mythtv] Frames Played issues

[Mark Spieth]

On 10/02/2020 11:30 am, Peter Bennett wrote:
> These are commits related to frames played and audio sync
>
> * 0e7e57f9c2 2019/03/06 Peter Bennett : Playback: Fix jerkiness with codec-deinterlaced content
> * 6a5fb07fa1 2019/03/04 Peter Bennett : AVSync2: Use frame timestamps to determine elapsed play time
> * 4089bf1ff0 2019/02/24 Peter Bennett : Playback: AvSync2 fix fast forward/rewind
> * 6b402ca5a3 2019/02/15 Peter Bennett : AVSync2: Improve resync speed and accuracy
> * 90b4ec347f 2019/02/15 Peter Bennett : AVSync2: Fix never-ending stutter on Live TV
>
> The change in 6a5fb07fa1 was to address the issue of frame count and 
> elapsed time getting out of sync and it worked surprisingly well, but 
> there are side-effects..
>
> In my opinion playback should use timestamps rather than frame count 
> to determine elapsed time, but that would be a major change.
>
> I believe that David Engel , Mark Spieth and John Pilkington had 
> problems with elapsed time going at the wrong rate before I made the fix.
>
> The problem was worst with the built in deinterlace of the shield and 
> in particular if you were running at increased speed (e.g. 1.5x).
>
>
I still get some issues when timestamps reset/wrap. This all assumes 
timestamps are monotonic increasing which is not necessarily true.

This happens every 26h for DVB so you choose your own luck. DVD's of 
course reset timestamps between successive split VOB files back to 0 
too. Perhaps this is why framecount was used in the first place by IJR. 
You can see some funkiness happen to the video when this happens. Concat 
2 ts files with ffmpeg for a taste.

Its much better than it was though.

Get a grinding sound when I skip at speed (not sure only because I never 
play anything at x1) which is a bit unpleasant. Changing playback speeds 
also skips a bit too so this is not smooth either. All shield 
experiences with current master.

Mark

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