H3 makes six to eight seconds well. Anything longer is a chain of takes, and the quality of the chain is decided at the joins. Most continuation setups feed the end of take 1 into take 2 as guidance: the model is nudged toward those frames but still re-samples them. That is close enough that nobody notices on a phone, and far enough that the frames after every join visibly shift brightness when you scrub through them. We measured it, replaced it, and measured again.
Academy / Video on one GPU / Lesson 5
Pro lesson · 7 min
Seamless joins: pin, don't guide
The usual way to extend an H3 clip leaves a small brightness step at every join. Locking the overlap with a noise mask removes it. Here are the numbers, the frame counts that work, and the two extra fixes for colour drift.
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