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

[John P Poet]

On Sun, May 9, 2010 at 4:08 PM, John P Poet <jppoet at gmail.com> wrote:
> On Sun, May 9, 2010 at 11:11 AM, David Engel <david at istwok.net> wrote:
>> On Sat, May 08, 2010 at 10:30:15AM +1000, Mark Spieth wrote:
>>> ive uploaded patch 6 which is the same as 5 but moved up my patch
>>> stack so there should not be any apply issues.
>>
>> Mark,
>>
>> 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.
>
> David,
>
> 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.
>
> A couple times, skipping backwards seem to completely confuse it and
> playback completely wedged up.  Skipping forward got it playing again,
> though.
>
> This is with 1280x720p60 recorded from ATSC (mpeg2) and from my HD-PVR (H.264).
>
> In general it is a major step forward and is very usable, but
> commercial skips are a bit jarring.
>
> I have not tried combining Mark's patch with my predictive-skip patch
> to see if it smooths it out any more.

I have actually used v5 of Mark's patch to watch a few shows with
timestretch on, and it is really quite usable.  v5 is a definite
improvement over early versions.

If I abuse it by jumping forward and backward a lot, I can get it
confused where it struggles to get the audio and video back in sync,
but for normal usage it does pretty good.


John
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