Yeah, that is a known issue.

The current VA-API implementation waits for the result after sending a single
frame to the hardware.

The OpenMAX implementation pipelines the whole thing and waits for a result
after sending multiple frames to the hardware to chew on.

So with OpenMAX the hardware is always busy, while with VA-API it constantly
turns on/off.

What	Removed	Added
Severity	normal	enhancement
Priority	medium	high