[MPlayer-dev-eng] New filter vf_ivtc, smart dropping of every 5th

[Arpi]

Hi,

> >>why do you need 6 frames for detecting duplicated frame?
> >>keep only the previous one (IMGTYPE_IP) and comtare teh current one with
> >>the previous, if the same, drop it.
> > Agree!
> 
> I think using 6 frames is more reliable.
> You can know for sure that the frame which was inserted is among this 6
> (last) frames. Thus you choose to drop that frame that is the most

The main prob. is that mplayer/mencoder is not designed to be a nonlinear
video editor. To handle frame delays by filters, it needs either ugly hacks
or partial redesign of the whole code.

> similar one. (Actually it is not that simple: for speed reasons not every
> pixel is compared; so if the filter detects a second frame which seems
> to be also similar to another frame, a second pass with comparing more
> pixels is performed.)

imho comparing every pixel isn't a big issue, the encoder does it a lot more
(when searching for MVs) for every frame. You don't even have to
implement/optimize it, libavcodec provides such functions.

> Using only the (difference to the) last frame may lead to false
> decisions. To decide whether to drop the frame in progress or not you
> would need a threshold for the difference since the duplicated frame will
> not be 100% the same (compression artefacts, etc.). But frames in dark
> scenes with little motion will also fall under this threshold. With some
> heuristics (drop only one frames out of five) you can avoid some of
> this mistakes, but not all.

what about doung it in 2 passes?
first pass would save the motion vectors (or the weightened absolute
sum of them) and you use that info for teh second pass.
duplicated frames have mostly 0;0 MVs while previous and next frame will
have similar, non-zero MVs.


A'rpi / Astral & ESP-team

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