Handbrake 1.0.7 Decomb Errors

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UserMT
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Joined: Thu Oct 12, 2017 1:04 am

Handbrake 1.0.7 Decomb Errors

Post by UserMT » Thu Oct 12, 2017 2:13 am

Hello,

First post but longtime user of Handbrake (still using 0.9.5). I occasionally run into old DVDs with difficult audio sync issues. I just tried the current version 1.0.7 and audio sync is perfect for these discs but there is a weird moiré pattern showing up in random places on the rips. The pattern is very noticeable and looks like a screen door moving in the attached example or like a progressive frame has been deinterlaced in others (jagged edges). The DVDs are progressive (no interlacing in the affected parts) but it looks like Handbrake is applying the Deinterlace filter or something. It happens for a short time (a scene or two) in the movie and then it goes away and looks normal until it comes back in another spot. It is repeatable and always in the same spots. I have found it occurs in most DVD rips using version 1.0.7. I tried using version 1.0.2 with the same results in the same spots using the Roku 480p 30 preset and only turning off the subtitle search. No other changes to the default setting. Versions 0.10.5 and and 0.9.5 do not show the effect and work normally (other than the audio being out of sync).

I found that if I turn off the Decomb filter the issue goes away and everything looks normal so maybe it has something to do with the way the filter sees the image and tries to Deinterlace it? Changing the Decomb filter type makes no difference. Only turning it off makes it go away. I am sure some of these old DVDs could have interlaced parts in them somewhere so I need to keep this filter on. Here is one example. Picture 1 shows the movie pattern with the Decomb filter on. Picture 2 shows no pattern and the filter is Off. This pattern is moving (almost flickering) so it is very noticeable. I also have the video clips from this example. They are about 8.5 MB each.

Image

Image

Handbrake Version 1.0.7. MacBook Pro using Sierra 10.12.4

Logs with Filter on and off

https://pastebin.com/DFzeiwKC
https://pastebin.com/LAdYZk7y

Any help would be appreciated. Thanks

UserMT
Posts: 4
Joined: Thu Oct 12, 2017 1:04 am

Re: Handbrake 1.0.7 Decomb Errors

Post by UserMT » Thu Oct 12, 2017 2:10 pm

Update: I changed the default Decomb filter setting to Less Sensitive and most of the flickering went away although it still shows up a little during the scene shown above and just before the scene change. The Fast setting shows more flickering than the Less Sensitive setting. Is there a way to turn down the sensitivity to match the earlier versions of Handbrake (0.95 and 0.10.5)? Note on above video - This scene is about 30 seconds into the movie so it should be at the beginning of the logs.

Woodstock
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Re: Handbrake 1.0.7 Decomb Errors

Post by Woodstock » Thu Oct 12, 2017 5:32 pm

The issue is probably that the horizontal lines in the scene itself are tripping up the decomb filter; It's trying to blend them out.

What happens if you turn decomb off, and use deinterlace instead?

UserMT
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Joined: Thu Oct 12, 2017 1:04 am

Re: Handbrake 1.0.7 Decomb Errors

Post by UserMT » Thu Oct 12, 2017 6:06 pm

How would you do that? This is a progressive scene. Wouldn't the deinterlace filter degrade the progressive frames?

Woodstock
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Re: Handbrake 1.0.7 Decomb Errors

Post by Woodstock » Thu Oct 12, 2017 6:38 pm

DVD sources are generally interlaced. Decomb is one way to deal with interlacing. If this were a Bluray source, I'd say disable decomb completely, because most BD sources aren't interlaced (but some are).

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BradleyS
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Re: Handbrake 1.0.7 Decomb Errors

Post by BradleyS » Fri Oct 13, 2017 4:30 pm

Less sensitive is the default from previous versions. As the interlacing detection works by analyzing the picture, certain patterns can throw it off but this is rare.

UserMT
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Re: Handbrake 1.0.7 Decomb Errors

Post by UserMT » Fri Oct 13, 2017 6:53 pm

Thanks for the replies. I tried this on 2 DVDs, the original Planet of the Apes and E.T. The problem was easily noticeable on both rips in many places, anyplace there were horizontal lines such as window shades and lattice fence in ET. Using the Less Sensitive setting helped a little on Planet of the Apes but nothing on ET. I tried an mp4 version of Planet of the Apes in HD using the exact same settings with the Decomb filter on . It looks perfect with no distortion and no moire anywhere. This must have something to do with the DVDs themselves but the earlier handbrake versions ripped them correctly. I can't believe I picked the only 2 DVDs to show this problem. I have not tied any other DVDs but I would think they will have the same effect.

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BradleyS
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Re: Handbrake 1.0.7 Decomb Errors

Post by BradleyS » Fri Oct 13, 2017 6:57 pm

I'm guessing that's a problem exacerbated by what is probably a lower quality SD transfer, with higher aliasing than the HD transfer.

Anyway, thanks for the report but given the design of the filter it's unlikely we can improve this. Decomb is on by default since 1.0.0 because that's the safest setting for most normal humans. Feel free to turn it off where you know your source is 100% progressive.

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