[nji]

Recently I discovered that some movies contain duplicate frames every n-th frame.
(This must have happened by changing the frame rate somehow.)
Now I wanted to remove that frames, but found no practical way.
There is no filter for that (maybe the filter interface doesn't allow to delete frames?),
and changing the frame rate by menu (video / frame rate...) does allow to remove
every n-th frame (by frame rate conversion to a specific fps) but
you cannot specify the "start frame" to remove.
So it happens that frames that contain information are removed,
while the duplicate frames are left in the stream. That is worse than before.

The only "solution" I found is to write all frames as image sequence,
then delete every n-th image, and re-read the remaining images.
Quite unpractical.

So my question:
Is there any solution how to do that task?