Compositing software struggles with any form of interframe compression like MP4 files.
The reason is that highly compressed file formats like that don't include full frame data. Only one out of every 60 frames or so is actually a real frame. The rest are just partial. So AE, Mocha, Nuke, etc. all prefer a proper production codec that has full frame information for every frame. Thus, a JPEG sequence, QuickTime with the PNG codec, Cineform, etc. will work better than an MP4 which uses the H.264 compression.
- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')
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