Delete duplicated frames from silent film?

[jagabo]

Fortunately wont have to use Vinverse() since the film was scanned in progressive HD...

You would think that would be the case, but there is combing that can be treated. Something is messed up with this scan or somewhere in the workflow

The problems are the fields are in the wrong position -- the lower field is above the upper field. Use the Field Swap filter in VirtualDub, or the SwapFields() filter in AviSynth, and all the comb artifacts go away.

4x Point enlargement, before:


and after SwapFields():

[poisondeathray]

Fortunately wont have to use Vinverse() since the film was scanned in progressive HD...

You would think that would be the case, but there is combing that can be treated. Something is messed up with this scan or somewhere in the workflow

The problems are the fields are in the wrong position -- the lower field is above the upper field. Use the Field Swap filter in VirtualDub, or the SwapFields() filter in AviSynth, and all the comb artifacts go away.

Yes that fixes it.

I don't know why some mjpeg encoders swap the fields. And some decoders have the option to swap during playback

I don't think you can do that losslessly in the mjpeg file

[yonkiman]

Do you see fine horizontal lines? The fields don't quite align, so you get residual combing. It's not real "combing" in the sense of interlaced fields, where each field is a different moment in time - that's real combing. That's why it's typically called "residual combing". That's why something gentle like vinverse is used to treat it instead of deinterlacing it (it's not interlaced)

Ah...I was looking for anomalies on vertical edges.

I don't know how to get vdub to process the dedup log (or any log), or how to program that part (without using avisynth to remove the duplicates)

Well the inelegant but effective (assuming Windows doesn't take the focus away while it's running) way would be to write a python program to read the dedup log and convert that into right arrow or delete keypresses in vdub. Just found this on Stack Overflow:

import win32com.client as comclt
wsh= comclt.Dispatch("WScript.Shell")
wsh.AppActivate("Notepad") # select another application
wsh.SendKeys("DEL") # send the keys you want

[poisondeathray]

looks like a start, but you probably have to modify that a bit, and/or the log format

let us know if you get it working with vdub , python, or other programs

I attached the log file for your test file for debug purposes

It's pretty easy to run dedup's 1st pass - just a simple 2 line script and use something like vdub file=>run video analysis pass

AVISource("video.avi")
DupMC(log="duplicates_log.txt")

[yonkiman]

looks like a start, but you probably have to modify that a bit, and/or the log format

let us know if you get it working with vdub , python, or other programs

I attached the log file for your test file

No doubt, but reading the log and turning it into DEL or -> is pretty easy in Python. Thanks again PDR!

[yonkiman]

The problems are the fields are in the wrong position -- the lower field is above the upper field. Use the Field Swap filter in VirtualDub, or the SwapFields() filter in AviSynth, and all the comb artifacts go away.

Ah! You and poisondeathray have a good eye - what are, you video experts or something?!?! I was looking for that but didn't look close enough. Thanks a lot for the photos and the detective work!

[yonkiman]

Just wanted to follow-up and say you two were a great help - My AVIs now have no duplicate frames and native frame rates of 16fps (reg8) and 24fps (super8). And they're de-combed. And I'm now comfortable using AviSynth - thanks again for everything!