Importance of RC average period & RC up/down reaction?

How important are these settings, and will changing them increase the quality of a movie? I've noticed sometimes that the codec will not encode black solidly right away (e.g. opening credits, after logos appear, the black background will be macro-blocked until the next keyframe). Would altering these settings affect this at all? I'm curious because I'm still having trouble with "True Lies", and even with a 70% compressibility (after C3D, movie is fine except for frames with black ~~> night sky, tuxedos, etc..), black is still not encoded right, like the codec doesn't react fast enough. Aside from the macro-blocking of black, everything else looks good. Will altering these values help me any, or should I look elsewhere? EDIT: Well, in viewing my movie in both VDub and watching it using ffdshow/BSPlayer, it appears as though the blocking is only a playback issue, but not on my LCD, but rather my TV. i'm playing the movie on a basic 20" TV, could this cause blocking? In viewing the movie fullscreen on the monitor, no blocking is apparent (with or without ffdshow's post-processing), but on my TV blocking is apparent (post=max ~~> more blocking, post=off ~~> less blocking). does this sound possible? if so, what could be done to correct this problem?

Change RC averaging period to half the number of frames, or slightly under. If it's 144855 frames, I usually just do like, half of 140,000, or 70,000. Never go over half. Leave all other settings @ default.

@OvERaCiD23 Well, the black-blocking issue is being discussed in detail for a while in the "lumi-masking" thread in XviD forum. Actually it's a problem related with all codecs. Taking a look at that thread might be of some help to you. regards, iago