[FFmpeg-user] Avoid yadif auto format for progressive bgra

[Robert Nagy]

I have a problem with yadif where a progressive bgra video stream is
converted to yadif supported formats even though yadif does not do anything
to the stream (auto_enable==true).

My question is whether I can solve this using a split and some form of
"conditional" filter? e.g.

                      /-> if interlaced   -> auto-format -> yadif ->\
source->split ->
 -> merge -> sink
                      \-> if progressive ->                              ->/

Is this possible? And will it work as I assume it would? I guess it would
not work for streams with both interlaced and progressive frames, but does
such stream exist?