Decomb problem

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jkauff
Experienced
Posts: 95
Joined: Thu Nov 22, 2012 1:27 pm

Decomb problem

Post by jkauff »

I just got the DVD of the film Pygmalion. I played it on MPC-HC with LAV software deinterlacing enabled, and it looked fine.

I ran it through the latest released version of Handbrake with my usual setting of Decomb=Default, and the resulting file had a lot of combing artifacts. I got pretty much the same results using Bob. I finally tried Deinterlacing=Slower, and the result looks much better.

Decomb has worked pretty well on my DVDs in the past. Any idea what might be different with this source DVD? I assume Decomb hasn't changed in the Nightlies, so is there anything else I could have tried?

Original encode log: http://pastebin.com/u2Sf9ZV3
mduell
Veteran User
Posts: 8187
Joined: Sat Apr 21, 2007 8:54 pm

Re: Decomb problem

Post by mduell »

Code: Select all

[18:05:20] decomb: deinterlaced 35694 | blended 3451 | unfiltered 119174 | total 158319
It was active, but decided not to deinterlace some frames.

Can you post screenshots of the missed combing? May need to adjust the sensitivity.
Deleted User 13735

Re: Decomb problem

Post by Deleted User 13735 »

It may be hard telecined
jkauff
Experienced
Posts: 95
Joined: Thu Nov 22, 2012 1:27 pm

Re: Decomb problem

Post by jkauff »

jkauff
Experienced
Posts: 95
Joined: Thu Nov 22, 2012 1:27 pm

Re: Decomb problem

Post by jkauff »

musicvid wrote:It may be hard telecined
Would MediaInfo identify that? How would I know?
.halverhahn
Posts: 1
Joined: Fri Jul 31, 2015 9:59 am

Re: Decomb problem

Post by .halverhahn »

Usually movies are telecined 23.976 fps->29.970 fps
Your source is: 720x480, pixel aspect: 8/9, display aspect: 1.33, 29.970 fps

So just enable detelecine and leave decomb and deinterlace off

.halverhahn
Deleted User 13735

Re: Decomb problem

Post by Deleted User 13735 »

I don't see any telecine in those three frames.
I think the source is so grainy the decomb detection is failing in Handbrake.
There are custom deinterlace settings, but you'll have to learn about them and run your own experiments.
jkauff
Experienced
Posts: 95
Joined: Thu Nov 22, 2012 1:27 pm

Re: Decomb problem

Post by jkauff »

Detelicine did not reduce the combing. Deinterlace=Default seems to provide the best results so far.

How do I go about adjusting the sensitivity of Decomb? I looked up the command line documentation, and only found a long string of numbers with no explanation for what they mean. The source is exceptionally grainy, but I collect a lot of movies from the 30s and 40s so I'd like to know the best settings to deal with these sources.
Deleted User 13735

Re: Decomb problem

Post by Deleted User 13735 »

Try a weak denoise filter as well with various deinterlace options.
The string options are documented -- keep digging.
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BradleyS
Moderator
Posts: 1860
Joined: Thu Aug 09, 2007 12:16 pm

Re: Decomb problem

Post by BradleyS »

The decomb string "393:2:1:1:2" is more sensitive and uses a more accurate interpolation method. Useful on troublesome content, albeit slower.
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