more multidecimate questions

[theeht]

If anyone would like to help me with this, I'd be much obliged. I'm working on encoding a capture of a VHS source, a Russian 1927 silent. Capture is in Picvideo MJPEG q19, 352x472, 29.97 fps using VirtualDub.

I did the first pass w/following script:

LoadPlugIn("C:\Program Files\AviSynth2\plugins\Decomb500.dll")
loadplugin("C:\Program Files\AviSynth2\plugins\multidecimate.dll")
SegmentedAVISource("G:\mary\mary4.avi")
Trim(41,105042) ++ Trim(105808,142342)
Telecide(Order=1,Post=0)
MultiDecimate(Pass=1)

then played the file all the way through.

I then ran Multidecimate.exe, pointed to the mfile.txt, and chose "Remove Duplicates: Global: Naive". It created the files it was supposed to very quickly. I then loaded my 2nd pass script:

LoadPlugIn("C:\Program Files\AviSynth2\plugins\Decomb500.dll")
loadplugin("C:\Program Files\AviSynth2\plugins\multidecimate.dll")
SegmentedAVISource("G:\mary\mary4.avi")
Trim(41,105042) ++ Trim(105808,142342)
Telecide(Order=1,post=0)
MultiDecimate(Pass=2)
AddBorders(0,4,0,4)

Problems:
1) There are still intermittent combing artifacts. These are related to Telecide, not Decimate, correct? So I need to do postprocessing? I tried:
Telecide(Order=1,post=2,vthresh=30)
as advised in the Decomb tutorial, and that improved things. But should I have used those settings for the first MultiDecimate pass in order for that to work correctly?

2) There are still a fair number of duplicate frames--I didn't measure, but probably around 1/second. I don't understand how to tweak it to improve.

3) The 2nd pass script results in a frame rate of 0.18fps, so the movie (orig. 79 minutes) now clocks in at over 6 hours. Now it is possible that the frame rate should be 18fps, if there was some simple calculation bug, though then the movie runs a bit slower than the VHS source, lasting more like 95 minutes. I simply don't know what the original frame rate was--this was not as standardized in the USSR as the US, and I'm sure there are other considerations related to restoration... Anyway, I don't understand why I ended up w/0.18fps or how I can get to the proper rate.

[manono]

Hi-

But should I have used those settings for the first MultiDecimate pass in order for that to work correctly?

If the interlacing isn't bad, I usually don't use the postprocessor on MultiDecimate(Pass=1), as it slows down the first pass. Nothing wrong with using the Vthresh setting or any other tweaks, though. But yes, it's better to feed MultiDecimate as clean a picture as possible.

I don't understand how to tweak it to improve.

Try it with "Remove Duplicates: Cycle Based: Protect Static Scenes". Before filling in the "Cycle" and "Remove", study the mfile. Try to find a cycle that begins to repeat after awhile (max cycle=250 frames). This can involve counting frames, sometimes many hundreds of frames in different parts of the video, until you're sure you've got it. For example, when using the regular Decomb, Decimate(5) removes one duplicate frame in every cycle of five frames. Your cycle may be much larger, if there is one to be found. If there is no cycle, try to find a Cycle/Remove that gets rid of as many of the duplicates as possible without removing any of the original frames. It's much better, for smooth play reasons, to have a few stray duplicates left over than to remove original content. After you've created the cfile and dfile, study the cfile in a few different places to see that most of the dupes were removed, but none of the original frames were removed. If it works right, and your source isn't too screwed up, the duplicate frames will usually have metrics of less than one, and the original frames will have metrics greater than one. But static scenes might mess that up, and blended duplicates may mess it up also. Blended duplicates may result from bad PAL2NTSC conversions, and you may have one, if you're unlucky.

I don't know how you wound up with .18fps, though. When you open the .avi in VDubMod and go File-File Information, does it also say .18fps? My guess is that it's a function of your player, as the length of the movie shouldn't change. But I don't use Global. In my tests it doesn't do as good a job as Cycle Based, and the audio can get asynch in the middle. I much prefer to set a cycle. But if you do use Global, tweak the Threshold (lower it) to remove more frames. You can create as many c and dfiles as you want, using any of the 4 methods, from the same original mfile. Studying the mfiles and dfiles is very helpful in teaching you how MultiDecimate works, and if it's done what you want.

And if you'd like me to have a look at it, I'd be happy to. This is my specialty. Just PM me.

[theeht]

Originally posted by manono
Hi-

[...]
I don't understand how to tweak it to improve.

Try it with "Remove Duplicates: Cycle Based: Protect Static Scenes". Before filling in the "Cycle" and "Remove", study the mfile. Try to find a cycle that begins to repeat after awhile (max cycle=250 frames). This can involve counting frames, sometimes many hundreds of frames in different parts of the video, until you're sure you've got it. [...]

I see... I don't think I have time for this at the moment! Esp. as I'm not understanding why, looking at the mfile, I see no duplicates at all. Even if I find two duplicate frames in Virtualdubmod and look for those very frames! I'm missing something, I'm sure.

I don't know how you wound up with .18fps, though. When you open the .avi in VDubMod and go File-File Information, does it also say .18fps?
Yes, it does!

And if you'd like me to have a look at it, I'd be happy to.
Thank you very much--I just can't delve into this any further right now. I'll have to be happy for now with my XVCD copy, and will save the capture in case I want to return to it later.