Filter interlace
  Convert progressive video into interlaced.
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
interlace AVOptions:
  scan              <int>        ..FV...... scanning mode (from 0 to 1) (default tff)
     tff             0            ..FV...... top field first
     bff             1            ..FV...... bottom field first
  lowpass           <int>        ..FV...... set vertical low-pass filter (from 0 to 2) (default linear)
     off             0            ..FV...... disable vertical low-pass filter
     linear          1            ..FV...... linear vertical low-pass filter
     complex         2            ..FV...... complex vertical low-pass filter


