i just solved the problem, maybe you can make sense of this:
i remembered the other day i used the effect “force motion blur” to fix some shadow issues, and i noticed that it also improved the quality of some 2d images in the comp…
so on a whim, i tried adding force motion blur to the project, and still nothing… then i thought, well let me try turning up the shutter angle to 360 (default is 180).
and woah! PERFECT. what a difference
the composition settings motion blur did not do anything, the “force motion blur” effect fixed it perfectly. go figure..
the problem is it takes much much longer to render.. i mean like 4 to 8x longer.
i reduce the time considerably by setting “samples per frame” to 2. setting it to 1 had no effect on the avi quality.
still, i don’t know why i am having this issue. somethings going on… but at least this is a fix for now…