When trying to produce video with a micro is that video timing is actually extremely tight and the eye is very sensitive to any timing errors in the video.This is why as the batsocks people point out its better to have a dedicated processor which only does the video generation so that you have control over the video sync signal generation process. If you try to run an application on the same processor which is generating the video then you are subject to timing errors because of interrupt latency and so on.What batsocks people do to avoid interrupt latency issues is to put the processor to sleep for most of the time so it has a known interrupt latency which avoids generating jitter in the video output.