[MEncoder-users] Swap or not swap (fields)

[Dieter]

> I found that some video files store the fields of each frame swaped, so
> when putting them in a DVD the result are that the scenes with movement
> are really ugly.

Mpeg can be top-field-first or bottom-field-first.  There is a flag that
is supposed to tell you which it is.

> And now the stupid question: is there a way of autodetect when the
> fields are swapped and fix it automagically?

Look at the flag and hope it is set correctly.  The real problem is what
to do when the flag changes every few frames.  Or when something upstream
has butchered things so badly that neither frame order is correct.