I'm currently working on some UI/UX motion studies at double the device's resolution, coming out to 2160 x 3840 at 30fps. I'm exporting using MPEG-4 codec and everything seems to be alright by and large, at least that format supports irregular resolutions unlike H.264, but I am not entirely satisfied with the MPEG-4's handling of thin graphics such as text and whatnot. Also, I find that Quicktime lags with many of these MPEG-4 exports in a strange way, however when those same videos are uploaded to Youtube they play at their true speed.
Does anyone have any recommendations to render out the best UI motion studies as to avoid or mitigate some of the issues I am encountering?
You can't avoid lines getting jittery. That's inherent in how block-based compression works. Uploading to a service that adds even more compression clearly doesn't improve matters. You can't have both - uncompressed files may retain the quality, bnut cannot be played in realtime, whereas compressed files will always degenerate the footage on some level. Otherwise you are simply looking in the wrong place. There's a million alternate players that have way better performance than Quicktime...