Help me get rid of blocking

[Eretria-chan]

Hello all,

I tried using MeGUI for testing an encode using the Constant Quality Anime profile, yet I get slightly visible blocks in the dark areas!
This is unacceptable (for me, not the GUI ;))! I want this encode to be "perfect" in sense that I cannot see any visual artifacts and let x264 go wild with the bitrate.
I am under the impression that constant quality will make x264 make sure that everything in the video has a constant quality (regardless of bitrate), yet I get blocking?

Can anyone suggest anything to change or do to get rid of the blocking? Lower the "quality" factor, perhaps?

Thanks in advance for any replies...

[Sharktooth]

x264 CRF is not properly constant quality, however i cant help without more info.

[Eretria-chan]

Damn, poorly coded source.
(Sigh... realized mistake after I posted >_< ... Don't kill me!)
So what exactly is CRF? I'm looking for the best option to set a given quality on the source, but let x264 choose the bitrate. CRF is the cloosest matching option, if I'm not mistaken?

[Dark Shikari]

Normally, x264's ratecontrol tweaks the ratefactor to reach your target bitrate. With CRF, you tell it a single ratefactor that it won't tweak.

Because x264 is merely good, not magic, this won't mean absolute constant quality, since we don't have a perfect algorithm for representing how the human visual system views video ;)

Your encoding settings may also affect x264's definition of "constant quality."

[Sharktooth]

CRF is Constant Rate Factor.
Also remember there is no best as per forum rules.
In your case, CRF is the closest option as possible to constant quality you may reach with x264.

[Eretria-chan]

Right, "best" is subjective... I have to be more careful with that word...

And since x264 isn't perfect, I still have to tell it what quality to use since it cannot read my mind ;) Ah, yes, but even so, it's still damn good!

Encoding settings are simply to achieve a video quality encoding with x264 with no artifacts or such! Setting a bitrate can be difficult since different sources require different amount of bitrate to compress depending on resolution, etc...
So, my goal is simply to tell x264: Hey, I want this kind of quality - how you achieve that is up to YOU! You can use as much bitrate as need to compress it efficiently, but I want no artifacts whatsoever present in the output.
(And since it says compress is as efficiently as possible, that means it shouldn't use a constant quantizer--it should use what quantizer is best suited without sacrificing quality.)

From what I understand, CRF is best suited for this! :D

:thanks: for the answers. I think I know a little more about the internals of x264...

Btw, your profiles rule Sharktooth. They make it so easy to encode without knowing what options to use.
So an extra :thanks: to you!