Decomb Comparison/Question

[DaWolfman]

Hey guys, I've been leeching these forums for a while now, and I just figured I try to contribute a little, even though I am a bit of an amateur.

I use DeComb in AviSynth to deinterlace/iVTC all of my DVD rips. I usually didn't bother with changing the various settings, because hey, Donald Graft's a pretty smart guy, he probably has the thing already configured to perfection...

But I noticed that some of the frames from my rip of "Fast and the Furious" contained artifacts. As it turns out, DeComb was unnecessarily deinterlacing good frames. I changed the vthresh values from the default value of 50 to 65, and here are my results:

vthresh 50, Frame 57084
http://www.personal.psu.edu/dnm138/testpics/crap0.png

And with vthresh 65...
http://www.personal.psu.edu/dnm138/testpics/good0.png
If it isn't already obvious, check the grille of the yellow car to see the difference.

And here's another one:

vthresh 50, Frame 103560
http://www.personal.psu.edu/dnm138/testpics/crapb0.png

vthresh 65
http://www.personal.psu.edu/dnm138/testpics/goodb0.png
This example was even worse because there were several of such frames in a row, making it obvious to even the untrained eye.

Before encoding, find an area with a high-contrast grid-like pattern, like car grilles or roof tiles. If they get distorted, check DeComb to make sure it isn't unnecesarily deinterlacing it.

But I have a problem for all those brilliant minds out there:
http://www.personal.psu.edu/dnm138/testpics/huh1.png

This image was from my encode. I checked the VOBs with Decomb at vthresh of both 50 and 65, and I could not reproduce this distortion on Vin Diesel. This leads me to think x264 is still buggy, any thoughts on this?

Video Codec: x264, rev. 293
Bitrate: 690 kbps


Thanks everyone-

-DaWolfman

[MOmonster]

Such picture I also get sometimes with decomb. First, because of your problem that some pictures get unnecessarily deinterlaced, why not using post=0? If the combing is only on a really small part of the picture sometimes telecide use the wrong match. You should test tfm(pp=0) and see what happens, else there is only the overwriting of the matches left (direct or with yatta or so).

Edit: Oh these are allready the encoded outputs. Could you please have a look at the preview of virtualdub, if there is also this problem.

[Guest]

My default vthresh errs on the side of caution; otherwise I'd have people complaining about stray combs.

For intransigent bad matches, use a manual override.

[DaWolfman]

Such picture I also get sometimes with decomb. First, because of your problem that some pictures get unnecessarily deinterlaced, why not using post=0? If the combing is only on a really small part of the picture sometimes telecide use the wrong match. You should test tfm(pp=0) and see what happens, else there is only the overwriting of the matches left (direct or with yatta or so).

Edit: Oh these are allready the encoded outputs. Could you please have a look at the preview of virtualdub, if there is also this problem.

I already checked with VirtualDub using Avisynth. I scrolled through the sequence frame-by-frame and I could not detect the artifacts. In other words, the source was clean, but the output was flawed.



My default vthresh errs on the side of caution; otherwise I'd have people complaining about stray combs.

For intransigent bad matches, use a manual override.

Sorry Neuron2, I wasn't implying DGDcode was flawed, I was just reminding the inexperienced ones out there (like myself) to experiment a little with the settings if they want better image clarity. Don't get me wrong, Decomb is awesome. It's the best deinterlacer/iVTC-er I tried so far (and I've tried many :mad: ).