Sets
the frame rate for recording as the time duration of each frame in microseconds.
This is useful for setting non-integer frame rates; for example, 12.5 frames
per second of a PAL videodisc: 1000000/12.5 = 80000 microseconds. The default
frame duration is 66,667 microseconds, equivalent to 15 frames per second.
The maximum frame duration is 1,000,000 microseconds (1 frame per second),
and the minimum frame duration is 33,333 microseconds (30 frames per second).