Detelecining videos

Deinterlacing should only be used for broadcast videos where all frames are
interlaced, NEVER for movies which have been telecined. Movies are
telecined to add one extra frame for every 4 to convert from 24fps to 30fps
for creating NTSC videos. Deinterlacing will still leave duplicate frames
and sometimes multiple duplicates in a row. This will cause even more
judder and make good spot removal impossible for plut-ins, and more
difficult for manual frame by frame removal. As to deinterlacing, the best
free one is probably QTGMC. Most deinterlacing uses interpolation which
smears fine details, while detelecining can mostly restore the original
24fps movie. PAL DVDs from movies are progressive without any interlacing,
but have speeded up the frame rate to 25fps, so for them detelecining is not
an issue. Properly made Blu-rays should have the original 24fps when made
from movies, or 23.976 fps for NTSC. If you want the true frame rate for
PAL, they can just be slowed to 24fps, but that is a small adjustment that
you might not notice.

Modern properly telecined movies will have 3 progressive frames followed by
2 intermixed interlaced frames. Some older telecine machines apparently
create 2 progressive, followed by 3 interlaced, and there are other
patterns, some of which seem random. IVTC can handle the standard modern
pattern, but cannot work with other patterns. The 2 progressive and 3 mixed
interlaced seem to be fairly common for public domain movies on DVD. This
makes it difficult to create a good restored version. Conversion from a PAL
movie to NTSC has sometimes been done by adding one extra frame for every 5
progressive frames. For smoothness of action this could be done by just
adding a duplicate, or having 4 progressive and 2 interlaced, but possible
other combinations.

There are also other methods of telecining which mix frames by creating
ghost images of the nearby frame in order to generate the extra frames to up
the frame rate from 24 to 30fps (actually 29.97). Those are extremely
intractable.

Well made DVDs from movies can be detelecined by specifying the first frame
of the pattern and then having the plug-in follow the same pattern, but the
old public domain movies on DVD are most often not properly telecined. Some
are just copies from off the air videotapes which introduce duplicate or
dropped frames when played.

A modified IVTC plugin for the 2 progressive frame telecines would be a big
blessing, but would not solve all problems.

From: noreply@sourceforge.net noreply@sourceforge.net
Sent: Sunday, August 1, 2021 9:05 PM
To: [vdfiltermod:tickets] 422@tickets.vdfiltermod.p.re.sourceforge.net
Subject: [vdfiltermod:tickets] #422 Detelecining videos

Hum... Why do you just not use the filter "deinterlace"? I use it for any
DVD from any zone & I don't have any problem...

[tickets:#422] https://sourceforge.net/p/vdfiltermod/tickets/422/
Detelecining videos

Status: open
Created: Thu Jul 22, 2021 06:49 PM UTC by John Clement
Last Updated: Thu Jul 22, 2021 06:49 PM UTC
Owner: nobody

The 32 bit version of Virtualdub2 has a plugin IVTC that detelecines modern
DVDs with 3 progressive and 2 interlaced very nicely. But there are a number
of legacy DVDs with 3 and occasionally more interlaced fields in a sequence
of 5 full frames. It would be nice to have a verstion of IVTC included in
VDub2 that can detelecine such DVDs.

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