[MPlayer-users] Feature request: averaging captured AVIs

[Levente Novák]

>> Would it be possible to extend Mencoder's functionnality to allow 
>> averaging from several pre-recorded AVIs, like it is possible with some 
>> other software (IIRC)? It would allow getting rid of chroma/luma noise 
>> originating from analog (VCR, Camcorder, etc...) captures.
> 
> I dont fully understand what you want to do.
> 
> Do you want to do an avarage over a few files that actualy
> contain the same movie, but captured from a different "source"
> to filter out space noise ?

Yes, but not necessarily from a different source. It could work well 
also if recorded from the same source but several times, as noise would 
vary between the different captures but not the image. Thus averaging 
would iron out noise. This would allow to preserve the original 
resolution, as "classic" noise reduction filters e.g. temporal denoise, 
linear blend etc... all degrade it to some extent.

> If it's this, then i dont think it is easily possible with
> the current mencoder design.

I am wondering how avisynth does it. I can imagine it would be enough to
read one frame from each file, then average them (by arithmetic or 
median averaging), and the resulting frame would be then processed (if 
necessary) by the other filters. Then next frame would be read from the 
master files, and so on. In other words, in case of averaging from 3 
sources, 3 frame reads (1 from each of the 3 different sources) would be 
necessary, then these 3 frames would be averaged to get one. From this 
point, everything would happen as it is already the case now.
Of course, the sources need to be completely synchronised and of the 
same length, but it is easy to perform this with e.g. Avidemux.


Levente