[mythtv] [PATCH] high speed smooth motion video

Tom Hughes tom at compton.nu
Sat Feb 5 19:12:04 UTC 2005

In message <4204D161.2010100 at wildgooses.com>
          Ed Wildgoose <lists at wildgooses.com> wrote:

> What I would personally really like is a very high speed fast forward a
> bit like the Sky+ boxes so that you can still quickly skip through
> adverts, but get a chance to "skim" them (like a x30 or a x45 speedup).
> Also in the UK I sometimes find it hard to tell when the adverts are
> skipped when I am jumping around in 30sec and 2 min jumps.  We often
> have trailers for similar shows near the end of the adverts, or the show
> might otherwise be hard to tell from just a few frames if it's an advert
> or not.

Current CVS code seems support speeds from x10 up to x180 for
rewind and fast forward.

Something strange seems to have happened in the last week though. This
morning I upgraded from the ATrpms 20050129 build to the 20050203 build
and found that rewind/ff behaving oddly - when returning to play again
the audio was normal speed but the video was slow motion.

I then built my own version from CVS and found that the slow motion
effect had gone but the rewind/ff seems a lot more jumpy. In fact it
looked at first like it kept jumping back a bit and then forward again
while fast forwarding.

I've looked at it some more and I noticed that if a scene is fairly
static then the fast forward is fairly smooth. I think what has
happened is that the frame displayed is now updated more often which
means that in a fast changing scene you don't get to see each frame
long enough for it to really register, but equally you don't see enough
frame to follow the action properly. The resulting effect is quite


Tom Hughes (tom at compton.nu)

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