Deblock filter

[Chengbin]

Does MVDegrain do deblocking? If not, what filter should I use for deblock. I have a lot of time.

[mgh]

deblock+dfttest combination among others

[Adub]

MVDegrain, as it's name suggests, is meant for degraining footage.

The most often used filters are as mgh said, deblock and dfttest. Also, take a look at deblock_qed().

[Sagekilla]

Yes, MVDegrain is meant for degraining video. But, it can do some primitive deblocking through it's averaging. If you have anything with horrid blocking though, you're better off using deblock, deblock_qed, or maybe dfttest with the right settings.

[buletti]

On the contrary MDegrain may introduce blocking when not used with overlapping blocks.

overlap = 0 (http://s5.tinypic.com/2qa8tgi.jpg)
overlap = blocksize / 2 (http://s5.tinypic.com/2s6smsg.jpg)

[Chengbin]

In AutoMKV I get this for DGdecode_Deblock(cpu=

http://i42.tinypic.com/2100s9s.png

What should I choose?

Is deblocking safe? Is there a case where I shouldn't use deblocking (as in it will hurt quality)

[Adub]

The process of deblocking can hurt video that is completely "clean", but most of the time it won't be a huge difference. Basically, go through the deblocking options and figure out which works best for your source. There is no "perfect, fits-all" answer. If there was, then there would only be one deblocking option vs 6.

Oh, the deblock option of DGIndex is only one option, remember that. Feel free to check out the other plugins that we have suggested.

[Sagekilla]

@buletti: That's hardly any news that using no overlap with MAnalyse introduces blocking. To do so is just a very bad idea if you're trying to do most kinds of filtering. Use overlap and you don't get any blocking. Simple.

[Chengbin]

@buletti: That's hardly any news that using no overlap with MAnalyse introduces blocking. To do so is just a very bad idea if you're trying to do most kinds of filtering. Use overlap and you don't get any blocking. Simple.

I'm sorry, I don't understand this overlap stuff. What do you mean by that? I'm using AutoMKV and under advanced profile editing there is the MVDegrain option and the deblock option. I choose MVDegrain 3 and deblock cpu=6 (look at my screencap). Is that OK?

Oh BTW, how come deblocking doesn't seem to be affecting speed? MVDegrain 3 significantly slows encoding down, but I get the same frame rates, maybe even very slightly faster, with deblock on.

[Sagekilla]

That's because the deblocking built into MPEG2Source is very fast. When you consider that MVDegrain3 is among the slowest denoisers, that just furthers the performance gap. Use any slow enough filter in a chain, and anything else you add that's faster will seem like it's coming for "free."

[Chengbin]

Is that deblocker good? Is there any better ones? Do you know how much better (like a little or a lot)

[Sagekilla]

I don't do deblocking normally because I very rarely run into sources that require it. IMO though, you have to tweak the MPEG2Source deblocker carefully or you'll destroy your detail if you use it without using smart settings. You want it to deblock just enough so they aren't noticeable, but not so much that you're turning it into mush.

You can usually do this just fine: MPEG2Source("...", cpu=2, moderate_h=30, moderate_v=30)

Note, moderate_h and moderate_v (for horizontal and vertical deblocking, respectively) are on a scale of [0, 255]. Lower values are stronger deblocking, higher is weaker. Tweak it and try to find the most tolerable blocking so you don't soften the image too much.

[Chengbin]

So maybe I should back it down to like 3 or 4?

I'm using deblocking because I do need it. It is not terrible, but the blocks are noticeable, and some frames are very bad.

BTW, what do you mean by smart settings?

[Sagekilla]

Sure, you can use moderate_h=3, moderate_v=3, if you want your source to lose any semblance of fine detail. moderate_h=20, moderate_v=40 are already fairly strong settings. I gave you the line for moderate_h / moderate_v = 30 for a reason: if you use too low of values you won't have any fine detail ever. Smart settings means you're not turning your source into a blurry mess here. It's no secret that too heavy of deblocking will completely destroy detail. That's what will happen if you use single digit moderate_h / moderate_v thresholds.

As I said in many threads so far, try it yourself. You won't learn unless you experiment. What happens when you set moderate_h and moderate_v to 0? To 20? 255? Play with the settings. Experiment. Learn. Asking questions is good, but nothing beats personal experience ;)

[Chengbin]

I'm learning. I don't have the time or patience to do that (since I'm only doing deblocking for a few videos). I'll certainly try when I have time.

[Sagekilla]

Good that you are, but my point is that you don't need to do excessive testing. It only takes a few minutes to check the difference between 3, 20, etc. Using avsp, you can flick through three examples very quickly:


a = MPEG2Source("...", cpu=2, moderate_h=3, moderate_v=3)
b = MPEG2Source("...", cpu=2, moderate_h=20, moderate_v=20)
c = MPEG2Source("...", cpu=2, moderate_h=50, moderate_v=50)
Interleave(a,b,c)


Just remember, if you want to get good quality out of any crap video (which is in itself difficult), you have to fine tune your settings to the video and work with it carefully. If you don't have the time to do this, you're only going to get crap out again.