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Old 18th December 2020, 15:59   #14  |  Link
poisondeathray
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Join Date: Sep 2007
Posts: 5,345
Quote:
Originally Posted by nji View Post

I would like to add just one aspect I observed
if the dupes are not pure (bit-wise identical).

Strangely enough this is the case for many already
already existing "still frame" movies
where one might want to get rid of the useless huge amount
of video data.
I would have bet it works for them too,
but a closer look reveils that the codecs produced
slightly different frames.

Yes - for non pure duplicates, the more noisy, the more space saved. It's pure duplicates that don't "cost" much. This can be a significant savings if there are many duplicates

This is also the "grey" area mentioned earlier about accuracy of duplicate detection. The threshold is not always accurate because of grain, noise, wobbly transfer, lossy compression. It takes some human eyes to get it right, or you might drop good frames, or keep noisy duplicates . Pure or very similar duplicates are much easier to detect accurately


Quote:
I wonder why all these conditions (especially the ones
poisondeathray worked out) aren't provided by a fine
converter cfr > vfr, so nobody needed care about
compatibility, and saved huge amounts of space.
Pros / cons mentioned earlier.

It's not huge amounts of space, for typical "clean" scenarios. And for 1 frame "songs", several frame lectures - being able to seek within a song or a lecture is arguably more important than saving a few MB

Playback is a player/splitter/decoder issue . It varies. They all work for "normal conditions" with variable FPS's such as dedup where you have strings of <20 duplicates. Basically all theatrical movies will be covered. It's only when you have very large gaps (very small equivalent FPS) that some begin to have issues





Quote:
Originally Posted by nji View Post
Moreover DeDup seems to be for AviSynth v.2.5 and not for v.2.6.

It works with all versions, but it's x86 only. You can use it with mp_pipeline for avs+ x64 (avisynth 3.6.2)

Quote:

And one more thing I wonder:
Do all they take into account that similariy is not associative?
Take the sequence
10 11 12 13 13 15 16 has max. neighbour distance of 1, but the distance of 10 and 16...
and the sequence
10 11 9 12 8 13 7 14 6 has max. neighbour distance of 8, but the distance of 10 and 6...

If you're referring to duplicates out of order, or later in a sequence - dedup only works for consecutive duplicate frames . It keeps a reference placeholder frame for each string of duplicates
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