Is it possible to deinterlace after encoding?

[kartakis]

I 've converted a movie with Flaskmpeg using 2 pass encoding and I 've forgot to check for interlaced format. So after viewing the film I 've tried to use a deinterlace filter with nundub but I found out that I must use the full prosessing mode.
Is it possible to deinterlace the film without having to re-encode the movie again? If yes how?
Thanks,
Nikos

[Acaila]

Interacing is something that exists in every frame. No program can process every frame of a video with doing a decompress->recompress.