[FFmpeg-devel] [RFC] change to the "setfield" filter

[Tim Nicholson]

In the various kicking around of default interlace flag handling I have
worked on the premise that the default should be to honour the flag, and
override it in those situations where it is known to be wrong.

Currently the "setfield" filter is very useful as an override where
interlaced material is either flagged/interpreted as progressive (much
mxf for one) or with the incorrect field dominance.

However it does not at the moment cope with the situation where
progressive material is flagged as interlaced, this would be extremely
useful as the filter would then provide complete control to override any
defaults, and not just be a partial solution as at the moment.

The "-1" "auto" argument basically means "do nothing" and so afaik the
only point in inserting the filter with this as a possibility is in auto
generated scripts where the argument is derived from a variable which
may be set externally due to other factors.

Would it not make more sense, and increase the usefulness of the filter,
if "-1" was taken to mean "progressive"?

Then in the situation where the flagging is know to be incorrect placing
this filter at the start of a chain would ensure that any auto inserted
filters that honoured the flag would behave appropriately

Stefano, this filter was your baby, do you have a view on this?
What do others think?
-- 
Tim