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Post #725185

Author
YanniD
Parent topic
Help with interlaced video in After Effects
Link to post in topic
https://originaltrilogy.com/post/id/725185/action/topic#725185
Date created
30-Aug-2014, 12:12 PM
Last modified
30-Aug-2014, 12:23 PM
Edited by
YanniD
Reason for edit
None provided

As I understand it, each frame of the 16mm film has been captured by a camera that interlaces each frame, using the DV 4:1:1 format, with the individual frames physically advanced at a 30fps rate through the camera.

If each interlaced DV field is woven back together with its associate, each resulting progressive frame should have no combing unless the film frame moved between each field being captured by the camera.

DV 4:1:1 only captures 1/4 of the chroma in each scanline, so the pixel equivalent of chroma for each frame is only 180x480.  If the expansion of chroma is not performed properly, you can get what look like combing artifacts because of the huge horizontal chroma compression.

Ideally, one would want to use an expansion algorithm that is the exact inverse of the DV compression algorithm, but IIRC all you get is a range of DV decoders that do not necessarily match exactly and give varying results.

IIRC, there were some favoured DV decoders that did a better job than others and there were reviews on Doom9 (Cedocida being the best IIRC).

Avisynth has a very specific function created to properly expand DV 4:1:1 called Reinterpolate411().

I found Reinterpolate411() invaluable when capturing Star Wars laserdisc frames via DV and analogue capture card in an experiment to see which was better for fidelity to the original many years ago.

It is possible your processing of the DV requires a better DV decoder and/or initial processing via the Reinterpolate411() Avisynth function.

Since you seem to be using Avisynth for some part of the processing, I would recommend including Reinterpolate411() and using Cedocida decoder if possible to see if results can be improved, before resorting to interlace deflicker and sharpening processes to remove those "combing" artifacts.