FR: add option to drop frames

[goellner]

for scroll based animations some percentage of frames can be dropped, to bring the file size significantly down. the demo has a 25mb binary, which seems quite large

[juliendargelos]

Hi, I agree being able to control the frame density can be useful. I deliberately used a high-fps video for the demo to make it more visually pleasant, but also mainly to demonstrate that fsv can handle very low latency rendering (but yes, at the expense of the file size).

Yet this can already be done by pre-processing the input video using ffmpeg and the -framerate option. The fsv converter may also provide such option in the future.