[MPlayer-G2-dev] transcode filters

[D Richard Felker III]

On Thu, Apr 22, 2004 at 10:37:54AM +0400, Vladimir Mosgalin wrote:
> On Wed, 21 Apr 2004, D Richard Felker III wrote:
> 
> DRFI>This most likely indicates that the ivtc filter is buggy. It should
> DRFI>never output any interlaced material for purely telecined content.
> DRFI>If the original is a mix of telecined film and video, then all bets
> DRFI>are off...
> 
> Yes, it was about mix. In "good" case 32detect won't be needed. Just
> ivts,decimate.

Let me explain why this is bad design. At the inverse-telecine stage,
you already know which fields are duplicate, based on (here's the key)
more information! Once the frames get to the decimate filter, this
information is lost. So decimate has to make the decision again, based
on less information. And it can in principle make the wrong decision,
even though the right decision was already computer at the ivtc stage.
That's why I claim transcode's approach is bad.

> DRFI>This will result in ugly flicker in your movie where frames
> DRFI>incorrectly get deinterlaced rather than properly matched. You'd be
> DRFI>better off deinterlacing all the frames with a blend filter so it's
> DRFI>uniform at least...
> 
> Um.. But what about cases when there are 500-1000 interlaced frames
> after imperfect ivtc process in the whole movie on complex cases? They
> are noticable when they are interlaced, but they aren't if they will
> just flicker a little.

Why are there 500-1000 interlaced frames? If there's really a mix of
video and film/animation content in the original, then it makes sense.
But if the original is entirely telecined film/animation, there should
be at most 5-10 interlaced frames in the output, and preferably 0. If
there are that many, it means that the ivtc algorithm really sucks
(probably it's too dependent on tracking phase or not spatially
localized like it should be).

> Another oddity: on still frame, kerndeint was working _only_ if the
> output driver is xv, xvidix or sdl, but not with x11. Adding scale
> filter at the end of the chain disabled its effect with any driver.
> This was regardless thresh=0 (which I suppose is required to force
> deinterlacing still frame). What kind of bug is this?

Show me the command lines or something. Maybe kerndeint is buggy.
Necessary filters should be auto-loaded...

Rich