7 pixels by 4 pixels. Found that out by typing 1 the comp size fields and seeing what I got. What are you trying to do???
CS5.5 lets me create a comp 4 pixels x 4 pixels but rounds that up to 8 pixels x 8 pixels when it comes to render time.
Does CS6 offer anything smaller than 8x8?
Movies need to be quicktime Pro Res and are for low res LED panels played back through a media server.
I think you are looking at a pro rez compression limitation. Many codecs require specific sizes because their compression schemes work on blocks of pixels. 8 X 8 and 16 X 16 are common. If you need 4 X 4 you should choose a different codec. Try JPEG QT instead of ProRez. If ProRez files playback fine so will jpeg compressed QuickTime.
Just treated yourself to a 1mm plasma?
Re: JPEG QT.
I can get a JPEG sequence to render out at 4 x 4 but doesn't help as it's not a quicktime movie.
JPEG 2000 renders a minimum size of 8 x 8 all the other JPEG QT codecs seem to render out at 16 x 16.
Problem is all the Quicktime codecs scale the source so things end up as an anti aliased mess.
Even dropping the footage into an 8 x 8 pixel comp the results are the same with the exception of the Animation & Blackmagic codecs.
Ah well... The file sizes will be small so the media server should handle the lossless codecs.