I have noticed a problem on my PC when trying to use two different pieces of software I have which do video colourisation. One is Vegas Pro & the other is Pixbim Video Colorize AI.
Without going into any of the usual arguments I see on here about the pros & cons of both AI software and colourising B&W video, can anyone give me a possible reason and solution as to why I see a ghosting effect (a lag in the frames of the colourising) and how to remedy it?
I have tried converting the original B&W MKVs & MP4s to ProRes to see if it makes a difference but to no avail?
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Do you have duplicate frames ?
A) Is it really a lag in the colorization of frames ? ie. frame 5's color clearly appears in frame 6 ?
B) is it a mistake in segmentation ? ie. "coloring outside the lines" ?
If it's really lag, and the lag is constant, you can shift the chroma +/- "x" frames to match
If it's segmentation issue, then it's like a problem with the underlying colorization algorithm
I'm pretty sure it is A, so will have a go at what you suggest (though the PixBim software probably doesn't give an option to shift Chroma frames?).
I would have guessed (B) because the likelihood of 2 programs getting it wrong in the same manner is lower
What is the source video, does it have duplicate frames ? Is it really blurry or low quality ?
To shift the chroma, it's easier to work in a program that can handle YCbCr (also known as YUV) directly, such as avisynth
When you work in YCbCr , the Y channel is separate from the Cb,Cr channels (the latter are color difference channels and hold the color information). For example, most types of prores, such as prores HQ use YCbCr.
So you would offset the CbCr channels to match the "Y" channel so they align up temporally
I have tried it from a few sources, but all so far have the same problem? They are all B&W TV shows from the 1960s, and are all very good copies that were recently restored professionaly. Some are from DVD and some Bluray.
The effect I see is with the original being one or two frames ahead of the colourising, and very occasionally B&W when changing scenes.
I don't really use colorization software, but if faulty scene change detection, or faulty temporal analysis is used, that migth shift the chroma over frames
It just seems sounds unrealistic that a bunch of different sources ( good quality) would have the same issue with 2 different colorization methods
Did you try asking in the Vegas and the Pixbim Video Colorize forums ?
I am planning to ask in the forums you mention shortly.
I don't really use hybrid, but there should be a place where you can edit a script
A basic script that corrected for the color lagging 1 frame behind would look like this
src=LWLibavVideoSource("video.ext") Y=ExtractY(src) U=ExtractU(src).trim(1,0) V=ExtractV(src).trim(1,0) CombinePlanes(Y,U,V, planes="YUV", source_planes="YYY", sample_clip=orig)
If it's shifting the other way, you can use loop(2,0,0) for 1 frame, which just repeats frame zero