Blurred scenes/single field compression.

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rawdalain
Posts: 5
Joined: Sun Mar 18, 2007 7:22 pm

Blurred scenes/single field compression.

Post by rawdalain »

I tried ripping a few episodes of Futurama overnight using h.264, the default resolution settings, and deinterlace set to off. During certain scenes in "hell is other robots" and "fear of a bot planet" from season one, disc two, it appears that only one field was compressed for that scene, and then scaled to the same resolution as the rest of the content. It is a pretty obvious shift and appears to be reproducible for the same scenes.

jbrjake
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Re: Blurred scenes/single field compression.

Post by jbrjake »

rawdalain wrote:I tried ripping a few episodes of Futurama overnight using h.264, the default resolution settings, and deinterlace set to off. During certain scenes in "hell is other robots" and "fear of a bot planet" from season one, disc two, it appears that only one field was compressed for that scene, and then scaled to the same resolution as the rest of the content. It is a pretty obvious shift and appears to be reproducible for the same scenes.
What fps did you use? Afaik Futurama is NTSC Video so you need to specify the framerate as 30fps. If you leave it at "Same as source" HB will film decimate the video, which will lead to odd results with interlaced animated video content.

I'll see if I can locate the disc, to try to reproduce this...
Also you are aware, right, that not deinterlacing the video first will result in less efficient compression?

rawdalain
Posts: 5
Joined: Sun Mar 18, 2007 7:22 pm

Post by rawdalain »

The reason why I didn't bother with using the deinterlace filter is that it does not appear to deinterlace the episodes correctly (nor does Apple's DVD player software handle it elegantly). What I've noticed is that from one cut to the next in almost any episode, you will see that sometimes it deinterlaces correctly, and in others there are obvious field order problems. The best way to spot this is watching the characters' mouths because it is usually a static frame except for the mouth movement during dialogue.

jbrjake
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Post by jbrjake »

Please answer my question so I can attempt to help you. Again: what fps did you use?

rawdalain
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Joined: Sun Mar 18, 2007 7:22 pm

Post by rawdalain »

Sorry, forgot that bit. Yeah I had it set to auto rather than locking it to 29.97. I did try a different disk with it set manually and deinterlace after posting that, and frankly the degradation in quality (increase in stairstepping) from the deinterlacing makes it a questionable tradeoff for getting rid of the weird looking mouths when field order errors occur. I'm going to retry the original episodes I was talking about tomorrow when I get time with fps set manually, and I'll do one interlaced and one deinterlaced.

jbrjake
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Post by jbrjake »

Then there are no "obvious field order problems" as you reported in your last post, and it is also untrue to claim HB "does not appear to deinterlace the episodes correctly." You are simply decimating material that should not be. What did you expect would happen when you tried to deinterlace after pullup? How can it match fields when you're discarding frames?

As far as the quality of HB's deinterlacer...I don't know how much clearer anyone could be about that. I've posted pictures clearly demonstrating the stair-stepping. I've linked to Niedermayer's deinterlacer shoot-out which clearly shows ffmpeg's (the one we use) is the worst. I've warned people to avoid it whenever possible. I made an enhancement ticket to add a better deinterlacer. But the reason I was telling you to consider using it wasn't to get "rid of the weird looking mouths when field order errors occur." Those are occurring because you used same as source fps. The reason to deinterlace would be that you're using x264 in progressive mode, which cannot efficiently compress interlaced content.

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