Can QMF cause Problems with XviD?

[bond]

Hi as some of you already might know there is a new filter for avisynth available (called Quantified Motion Filter) which allows you to use different filtering for different motion levels:

Originally posted by HomiE FR
It splits the provided video clip into 3 motion levels: low motion, medium motion and high motion, using a (very) simple motion estimation algorithm. Then, it applies different user-defined filters for each motion level, allowing you to do some adaptive smoothing/sharpening (or anything else you want).read more about it here (http://forum.doom9.org/showthread.php?s=&threadid=56051&perpage=20&pagenumber=1)

now my question:
is it possible that fast "quality" changes in the picture provided to a codec (like xvid) through avisynth can cause problems or "non-optimal" results, for example because of fast changes of sharpness in a scene, or is the effect only positive...

[Danzel]

As far as I know it would depend on how different the frames looked after the filtering switched between filter sets.

If the results between your low / medium / high motion filters looked to much different then when it switched between them then xvid would most likely place an I frame, perhaps in a place where it wouldnt of placed it if you were just using one filter set.

Will this really cause troubles?
Perhaps, if your filtered material isnt made more compressible by your motion decided filters then the possible extra I frames may leave Xvid choking for bits.
However on the other hand if your filtering is chosen right (which i'd hope it would be :D) then the Extra I frames will be compensated by smaller P and B frames thanks to the extra filtering.
(I haven't played around with QMF yet so that is just what I think would happen, have a play with it and tell me what you get)

In Short: If your chosen filters are good, then better results can be obtained.

QMF sounds like it has the possibility to be a very powerful filtering tool.

Danzel.

[EDIT] If you check out the QMF thread you'll see some people are already having better results from using it