il[=d|i][s][:[d|i][s]]
(De)interleaves lines. The goal of this filter is to add the
ability to process interlaced images pre-field without deinter-
lacing them. You can filter your interlaced DVD and play it on
a TV without breaking the interlacing. While deinterlacing
(with the postprocessing filter) removes interlacing permanently
(by smoothing, averaging, etc) deinterleaving splits the frame
into 2 fields (so called half pictures), so you can process
(filter) them independently and then re-interleave them.
d deinterleave (placing one above the other)
i interleave
s swap fields (exchange even & odd lines)
