Post-processing filters?

[pfxz]

Hello,

I have bunches of videos here with jacked up colors, interlacing artifacts, other compression artifact or any combinations of the previously mentioned problems. They are all lossly encoded with various codecs, usually XviD, x264 or RV*.

I'd like to improve them somehow, and I know there are lots of programs that can do this. But I'd like to know if there are any filters (color adjustment, sharpening, noise reduction, whatever) that I can enable DURING PLAYBACK and so I can kind of preview the changes. It'd surely save me a lot of encoding time.

EDIT: Or better yet, what is the fastest way to preview an AVISynth output?

Thank you.

[pfxz]

Oh yes, and what would be the best way to get rid of these:
http://img294.imageshack.us/my.php?image=bloxjr6.jpg

I don't know exactly how to call them, but it's the blurry noise thing. Of course JPG compounded the problem, but it was already there.

[guns1inger]

You can preview avisynth scripts in virtualdub or media player classic, or by using AvsP for editing.

[jagabo]

KMPlayer has lots of filters and proc amp controls you can run at playback.