Originally Posted by knc1
That video is a good demonstration of what geekmaster reported.
That small areas of the screen can be updated much faster than the entire screen.
That demo is only updating about 1/4 of the screen.
Another interesting point -
That demo is running on one of the TI OMAP processors, the processor family that runs the Kindle Fire product line, not the Kindle e-ink product line.
But the K4 and K5 have an embedded eink controller in the SoC that can simultaneously do partial updates to 20 non-overlapping areas. And even with a fullscreen update, I successfully did up to 50 frames per second, but it gets horrible artifacts (like grayscale updates) if you go past about 18 FPS.
The K3 uses an external eink controller chip that has a hard limit of 7.7 FPS average (sometimes faster and sometimes slower), because the ioctl() calls do not return until that time. I slowed down all my code for all kindle models to run at the speed limit determined by the K3 firmware, because 7.7 FPS looked "good enough" and allows a consistent experience across platforms (and compresses better than a higher framerate).