Adaptive Quantization is back.

[Sharktooth]

Due to a massive request, i re-added the Adaptive Quant patch to my builds.
It works exactly as it was in previous builds.

[Sirber]

k. gonna add to realanime

[DarkZell666]

Actually, I'd like to know what fast-p-skip does better or not than adaptative quantization ...

If I got things right :

- AQ quantizes differently different parts of the frame where the eye "can't see the difference" (this only depends on the current frame I guess)
- fast-p-skip considers a bloc as a SKIP (identical to the same bloc on the next frame) "faster" (with hardcoded precision threshold or something?), which means that 2 blocs that were very similar but still different without fast-p-skip would be considered the same with fast-p-skip enabled.

Why should one feature exclude the presence of the other ? This question was bugging me since AQ had disappeared in the first place... if anyone can explain this to me please ? :)

[Caroliano]

:search:

And it is --no-fast-pskip
No, --no-fast-pskip disables the early skip detection on P-frames that has been present in x264 since revision 1, it's purpose is to help visual quality (and maybe psnr) on those clips where fast pskip detection performs badly, like the "bluesky" clip.
The current AQ pach only add more bitrate to the blue and black planes to prevent blocking there. It is not an pyscho-visual enchancement yet.

[DarkZell666]

actually I really did mean fast-pskip, (even if the cmdline option to disable it is -no-fast-pskip), talking about the concept in itself.

I got the point about AQ and the differences with -no-fast-pskip though, thx a lot !

I'll use search to find out why AQ has been removed in the first place =)

[Sharktooth]

it was removed coz it's not an optimal solution. it throws bits at dark and dark-blue areas even when there are no blocks.

[Sirber]

ok then, no add in RealAnime :D

[bob0r]

Like i said in #x264, its a feature, you can still add it, just dont have it enabled by default.
Got blocks? then click this option: .... bla
Now there is no "block detection", so its apply to all or do not apply to all.

AQ optimize has been added to people's todo lists.... just be patient :cool:

[Zero1]

I like the idea of AQ, since I'm of the opinion that some parts of a frame can be compressed more than others, similarly dark/light areas (debateable though), for example large blocks of colour vs fine detail. I might be wrong in my theory, but I would guess that using some form of AQ on anime, would work better than quantizing the whole frame at the same quant, for example compress the large areas of solid colours more than the detail so you would get a mixture of quants through a single frame (as Haali's current AQ implementation does, albeit it is a simple fix to help combat blocking in certain circumstances).

The other thing, if anyone decides to work on AQ, or if Haali finds some free time and is open to suggestions, I would like to request an option so that AQ adheres to --qpmin and --qpmax. One encode I set --qpmin 18 and found quite a lot of sections fluctuating and hitting qp 14 whilst other parts of the frame might be qp22, this might be intended though, so as to get rid of blocking, but in normal circumstances where blocking isn't so much of a problem, but AQ is wanted to bring a general quality increase (I guess like trellis, lowering quality in some areas and using the savings to increase the quality of more noticable areas), optimisation if you like, I think it not adhering to the --qpmin at least would be suboptimal for me.

Perhaps 2 types of AQ can co-exist in x264? The original that Haali wrote to fix blocking, and a new, general AQ that would save bits in flat areas and perhaps dark or light areas (or whatever is deemed better) that would act as "another form of optimisation" (Probably not the best way to word things, but I'm having writers block somewhat).

Cheers, hope you guys had good holidays (whilst I've been 'netless :p)

[unmei]

Thanks sharktooth. Even tho i didn't request it back, i still missed it somehow - imo it is a quite good feature for block prevention in anime.