advice on cleaning up the noise on this video

[rakan]

Hi guys,

I would like to get your advice about how to best encode this video clip I've been working with for the past few days. I'm kind of new to Megui and I've been playing around with the noise filters in an attempt to get the best result but I think I've hit a wall and I could use some help. Here are the links to the clip I've been working with...

http://rapidshare.de/files/39144877/chopped.vob.html (http://rapidshare.de/files/39144877/chopped.vob.html)

I think the clip suffers from a lot of grain or perhaps it's what you would call "high-frequency noise". I played around with some of the denoisers (convolution3d, hqdn3d, and fft3dfilter) but so far only hqdn3d has produced a result I would consider acceptable. I guess what I would like to know is whether I should try denoising using multiple filters or if there is anything else you guys would recommend I do to try to remove the grainy effect/noise in this clip. Thanks. Here is the avisynth script I have been using to produce what I consider to be the best result so far...

DGDecode_mpeg2source("C:\Documents and Settings\rakan\Desktop\chopped\chopped.d2v",cpu=4,info=3)
ColorMatrix(hints=true,interlaced=true)
tfm(order=-1).tdecimate(hybrid=1)
crop( 0, 2, 0, 0)
undot()
Hqdn3d(4,3,6,6)

LanczosResize(688,368) # Lanczos (Sharp)

[Ranguvar]

This belongs in AviSynth Usage.

Search around... there's lots, and lots of topics about this sort of thing.

Great threads:
http://forum.doom9.org/showthread.php?t=51181
http://forum.doom9.org/showthread.php?t=136433
http://forum.doom9.org/showthread.php?t=131279
http://forum.doom9.org/showthread.php?t=85790
http://forum.doom9.org/showthread.php?t=110078
and especially http://forum.doom9.org/showthread.php?t=132310

Have fun reading :)

[rakan]

Thanks Ranguvar!

Those threads were just what I needed, particularly the last one. I followed some of Didee's tips but I eventually used Sagekilla's script followed by hqdn3d. This gave me the best result so far. There are still issues with the shading in the dark areas of the clip but I don't think that it's a big deal. The movie is way more watchable than my other encodes. The dancing blocks are all but gone and the detail is pretty sharp. I'm even able to get the bitrate down to 550 kbps with a frame size of 720X400 with very little loss in detail... sweet! Thanks again!

[Ranguvar]

Of course :) And if you're having shading issues, try gradfunk, gradfunkmirror, or GradFun2db :)

http://forum.doom9.org/showthread.php?t=108681

It works best as post-processing, but it can help some with encodes too.

[rakan]

One more question...

I noticed an odd effect in areas with low tonal range. If you look at the sample video clips that I posted you'll that the darker colors in the sky in the background don't blend together very well, there is an observable separation as the colors transition from darker to lighter areas of the sky. I also see this effect in the original source although it is not as pronounced. Is there anyway to get the colors in these kind of "low tonal range" areas to transition better? Or is this avoidable since the problem appears to be present in the source?

The original VOB (http://rapidshare.de/files/39192092/chopped.vob.html)

My encode (http://rapidshare.de/files/39192099/chopped.mkv.html)


Edit:
I see that this effect is called a gradient or "banding", is this the proper terminology? You made some suggestions that will remove it on playback but I play these videos on my xbox where I don't have these playback options that are available on my computer so I'd like to try to remove this effect in from the encoded video if possible.

[Ranguvar]

Can't download ATM, but see my post right above yours ;)

[rakan]

I used gradfun2db and the gradfunk function by adding it to the avisynth section in the ffdshow settings. That does reduce the effect quite a bit. I also used the DeBand and Noise settings of ffdshow to reduce this effect with quite a bit of success. I think that this banding effect is a trade off since I first had trouble with noise and then when I encoded with the appropriate noise filters I see banding and I solve the banding by adding noise, seems illogical to remove noise and then add it but that is what appears to make the best picture. Maybe using a softer resize would help (I'm using Lancoz).

I store these movies on my xbox and use XBMC to play these movies on my TV. XBMC doesn't have the Debanding or Noise functions that are available on ffdshow on my computer so I still see occasional banding particularly in low tonal areas. I'm not sure if there is much I can do about that, I guess I'll have to accept the fact that with this much compression that some loss in the quality of the picture is going to occur.

[foxyshadis]

The only way to get rid of banding while encoding is to use a deband (like gradfunk) with very high settings, and encode to a very high bitrate, much higher than it would normally take to look good. Otherwise the dithering gets eaten alive.

[Blue_MiSfit]

Yep, banding sucks - no doubt about it :(

That's why I always add quite a bit of noise on playback. It has the added bonus of tricking my eyes into seeing more detail than is really present!

Good thing I like film grain!

~MiSfit

[thetoof]

Also, a very good way to encode at low bitrate without losing all your dithering is to use gradfun2db, add some grain with something like mt_average(AddGrainC(2),AddGrainC(2,seed=10))
and then stabilize it with GrainOptimizer at a very high tdist.

[discofever]

That's why I always add quite a bit of noise on playback. It has the added bonus of tricking my eyes into seeing more detail than is really present!


What filters add grain?

[thetoof]

Read my previous post...

Edit: and, if you want to do it in MPC, there's a filter in it that does it.

[discofever]

I should have said 'any other filters that add grain?' rather than 'what filters add grain?'

Poor wording on my part, I apologise.

[Adub]

AddgrainC is the main one. You only need one really.