I have a 30 second 4K clip shot in 29.97 which I imported into After Effects for chroma keying. I applied Keylight and overlaid it over a background still file and got a very clean key. Then I added a little camera move zooming in slightly on the composition. The problem arose when I exported it to the Render Que and rendered it out as a single file on my MacPro. Upon inspection of the rendered Quicktime file, it played beautifully for about 10 seconds then one or two frames switched to about 1/4th resolution then back to full resolution. This happens 5 or 6 times during the 30 seconds. I tried rendering it out in various codecs including a tiff sequence but the same problem happens often in different places in the file. I am baffled as to what to do to get a clean file. My only work around is to render it out several times and combine the successfully rendered parts of the various clips to get one one complete usable clip. I am sure this is not what Adobe had in mind. Can anyone help?
You can view the full clip at the following link: YouTube All the jumps and jitters are in the original file rendered from After Effects. The titles were done later in Premier. the two frames below show you the exact difference between two successive frames in the rendered image sequence from After Effects.
What exact version of After Effects are you using?
I am using 2014 but I just downloaded the latest patch and am rerunning the render again to see if it makes a difference. One difference I noticed right off the bat is that it was letting me see the comp in full resolution in my preview composition screen. this is something that only worked intermittently in the last version of AE.