Black and white pumping artifacts

[Pen-Pen]

hi

I've been searching the forum for an answer to this (specific) question but can't seem to find any solution

I'm trying to encode Schindler's List, which is, as everyone knows :

* very long
* in B&W

The problem I face is that these greyscale pixels seem to "pump" all the time (especially the lighter ones), so that the compressibility of the source is a real catastrophe

I tried using TemporalSoften (with standard values given in AviSynth doc and some other "harder" settings) but it doesn't seem to fix the problem

Is there another filter which would suit my purpose better ? Is there a really good solution to this kind of problems ?

thx in advance :)

[Guest]

Originally posted by Pen-Pen
The problem I face is that these greyscale pixels seem to "pump" all the time What do you mean by "pump"? Your problem description is unclear.

[sh0dan]

... you should probably watch the movie before deciding on greyscaling it.

(Hint: There is a tiny part of a sequence that isn't black/white)

[mf]

Not so tiny, and pretty obvious too :). Some quite bright red :).

[Pen-Pen]

yeah sure ;) I did do the right trimming ;)

And there actually are four parts (the beginning, the end AND twice that red thing you mentioned ;))

anyway...

when I wrote "pumping", I meant "flashing"... see what I mean ? These pixels that are meant to be white, and whose luminance varies all the time, giving you the impression that the image luminance is shaking... If not, I'll post a short sample when I get home in a couple of hours, it's quite difficult to explain, especially in English...

[Mug Funky]

hmm... kind of like an exaggerated "projector" effect? i've seen this done a lot in various places. nice effect if you've got enough bits to throw at it :)

more than 1 b-frame helps for this kind of thing. there's a 50:50 chance the b-frame can predict off its most similar adjacent p-frame (not the one with different luma), saving you a few bits. getting the frame decisions right requires a very smart codec though. haven't tried this type of content on it, but i'm sure xvid is up to the challenge on sensible settings (ie. b-frame threshold 0).

i may be wrong :)

i'd like to see a sample if that's okay. i haven't actually seen this movie so i can't do more than guess (ie, does the flicker go all through the movie or is it just in a couple of scenes? also, how much variance do you get?)

[Soulhunter]

Would limiting (maybe temporal) the luma-range help in this case... :confused:


Bye

[Guest]

Post a source clip if you want specific help.

[Pen-Pen]

http://users.skynet.be/fa022588/sample.avi

here's a small part of the movie, encoded with


mpeg2source("Schindler's List.d2v")
greyscale()
LanczosResize(512,272,2,18,718,542)
limiter()


actually, this kind of looks like heavy mpeg mosquito noise... but is it ONLY mosquito noise ? and if so, is there really a way to elegantly get rid of it (I once tried and ended up with quite an ugly encode :()

[scharfis_brain]

:confused:
neuron2 said: a source clip.

this meaning a unprocessed VOB fragment.

[JasonFly]

Originally posted by mf
Not so tiny, and pretty obvious too :). Some quite bright red :).

And also some yellow at the very beginning with the candle(or the end I don't remember) ;)

Zones in Xvid could cope with this situation if you know all the coloured zones.

[Pen-Pen]

Originally posted by scharfis_brain
:confused:
neuron2 said: a source clip.

this meaning a unprocessed VOB fragment.

wouaw, that can be huge... how many frames do you need ?

[Soulhunter]

Originally posted by Pen-Pen
wouaw, that can be huge... Zip them to gain some compression... ;)


Bye

[mf]

Originally posted by JasonFly
Zones in Xvid could cope with this situation if you know all the coloured zones.
You could also not use any artificial greyscaling, as the original DVD probably already has a constant 128/128 chroma plane except for the color parts. Not to mention that greyscaling saves <0.000000000000000001% bitrate when the source is already greyscale.