Controls how aggressively to insert extra I-frames (default:
40). With small values of scenecut, the codec often has to
force an I-frame when it would exceed keyint. Good values of
scenecut may find a better location for the I-frame. Large val-
ues use more I-frames than necessary, thus wasting bits. -1
disables scene-cut detection, so I-frames are inserted only once
every other keyint frames, even if a scene-cut occurs earlier.
This is not recommended and wastes bitrate as scenecuts encoded
as P-frames are just as big as I-frames, but do not reset the
"keyint counter".
