Banding effect when encoding...

[Henry The Ripper]

Hi!

What causes the banding effect, that makes walls etc. static objects to come alive? It's very annoying, but I can't find a solution to that.

Is it low bitrate or some filter that tries to use heavier encoding in places that human eye can't see "very" well?

I have had an movie encoded with the latest Xvid codec and bitrate was over 1000Kbps... I was trying to fit a 85min. movie to 700Mb and when the file size was by mistake 950Mb the picture was close to perfect...

I used latest GKnot 0.28.2 and choosed the final file size to be 700Mb, but the final size was 250Mb over that option...

I have tried to encode the same movie about 20 times, but can't seem to get rid of the banding...

I have noticed also that if I use bilinear filter there aren't any ringing effects, but with bicubic I get all sorts of crap messing the picture.

Is the any hope to correct the encoding process?

Should I post the .avs script used?

[manono]

Hi-

What causes the banding effect, that makes walls etc. static objects to come alive?

It's probably a combination of the MPEG4 compression and too low of a bitrate. MPEG4 is notorious for blockiness in dark scenes, and on solid colored portions of a scene, like on walls or skies, and for the so-called "moving walls" effect. However some of the codecs are better about it than others. But you gave one clue when you said:

I was trying to fit a 85min. movie to 700Mb and when the file size was by mistake 950Mb the picture was close to perfect...

So when you compressed the same movie to 700 MB, perhaps the bitrate was then too low, and the artifacts started to appear.

I have noticed also that if I use bilinear filter there aren't any ringing effects, but with bicubic I get all sorts of crap messing the picture.

Bilinear helps the compression a lot, but causes you to lose way too much detail. I personally wouldn't recommend using it.

The best advice that I can give is to recommend the use of GKnot's compression test. The results will help you to determine the optimum resolution and file size to minimize the annoying artifacts.

[Soulhunter]

You could use denoisers (like Deen, MipSmooth, FluxSmooth) to gain compression... ;)

Its also nice for higher bitrates, because noise in uniform areas will still have this "moving wall" effect !!!

Bye

[Henry The Ripper]

Hi!

Did my first GOOD LOOKING 700Mb rip today!! JIHAA!!

The problem I have had for months was so simple that it hasn't even been written in the GKnot guides...

You have to run Compressibility Check every time you change codec settings...

This could be a very good thing to mention in the guides, expecially for newbies.

Now I can also focus on quality! ;)