( Diese Seite in 
Deutsch )
SelectRangeEvery(clip clip[, int every][, int length] [, int offset][, bool audio])
This filter is available starting from v2.5. The filter selects length number of frames every n frames, starting from frame offset. Default values are: Select 50 frames every 1500 frames, starting with first selection at frame 0. (every = 1500, length = 50, offset = 0).
Starting from v2.55, SelectRangeEvery will also process audio. To keep the original audio, use audio = false.
Examples:
# Selects the frames 0 to 13, 280 to 293, 560 to 573, etc.
SelectRangeEvery(clip, 280, 14)
# Selects the frames 2 to 15, 282 to 295, 562 to 575, etc.
SelectRangeEvery(clip, 280, 14, 2)
