Encoding H.264 while preserving RGB colorspace / 4:4:4

[nnezz]

I have pure RGB video, mostly CGI type footage, that I wish to encode in H.264 while preserving the full 4:4:4 chroma.
From what I can read, the specification supports it via the H.264/AVC High 4:4:4 Intra/Predictive profiles.
But, I can't find any information on how to use this or which applications/encoders support it.

x264 won't take anything but yv12, so where do I go to encode in the full RGB colorspace?
I realize that RGB encoding currently is (much) less efficient than YV12, but I can live with that, as long as I'm able to do it

Please, any help on the subject is greatly appreciated.

Reference: High-Fidelity RGB Video Coding Using Adaptive Inter-Plane Weighted Prediction

(if I confused any terms, excuse me. I'm still learning)

[roozhou]

seperate RGB to 3 channels and encode to 3 AVC streams
for each stream:
assume R/G/B to be Y, and set each pixel in U & V to 128

[nnezz]

If I understand right, the idea is to separate each color channel (via avisynth?) treating each R/G/B as luminance while neutralizing the chroma. Then feed each luminance plane into x264 at the same time to produce a final encode?
Although it sounds more like you're saying I have to encode each stream separately, but if I do that then how do I combine the three channels afterwards to make a watchable final file?

I'm a little confused. Please be kind and elaborate a tiny bit on which app I should use for each step.

[J_Darnley]

Avisynth will do both processing steps for you.

For splitting use: ShowRed("yv12"), ShowGreen("yv12") and ShowBlue("yv12")
Re-combining: MergeRGB(red_clip, green_clip, blue_clip)

[nnezz]

I encoded each stream and got 3 very large files. The same 355MB 10 second file which ordinarily compresses neatly to 24MB, turned into 3 large streams each about 70MB, each encoded much slower than usual as well, using the same compression profile. Does this seem right?

Now that it's done, I can feed the files back into avisynth using the MergeRGB command, but how do I get the resulting output into a watchable file without re-encoding?

[J_Darnley]

play the avs file

[Dark Shikari]

Dirac supports YCgCo, which can be losslessly converted back to RGB.

[nnezz]

I've found a few other forum posts both here and other places on the web, and it seems that encoding in h.264 without chroma subsampling isn't possible atm. Maybe some day

Thanks for all your answers.

[kolak]

Use Cineform.

Andrew

[Blue_MiSfit]

Yes, that's an excellent idea

CineForm is a badass codec, and can preserve 4:4:4 nicely.

[kolak]

Originally Posted by Blue_MiSfit

Yes, that's an excellent idea

CineForm is a badass codec, and can preserve 4:4:4 nicely.

at 12bit

[egr]

Originally Posted by nnezz

I've found a few other forum posts both here and other places on the web, and it seems that encoding in h.264 without chroma subsampling isn't possible atm. Maybe some day

Thanks for all your answers.

I'm guessing this is no longer the case? Just wanna confirm...

Originally Posted by kolak

Use Cineform.

Andrew

Originally Posted by kolak

at 12bit

Well it looks like they've closed up shop...

[nevcairiel]

Cineform has been standardized as SMPTE VC-5, so even if GoPro shuts down their support, the standardized codec lives on.

[kolak]

Originally Posted by egr

I'm guessing this is no longer the case? Just wanna confirm...


Well it looks like they've closed up shop...

codecs is still very alive and now it's actually free.
Adobe, Resolve, Scratch all have native support now.

If you want o build own encoder for example you can drop line here and get your own SDK license key (if they decide it's worth it):
https://gopro.com/connect#cineform

[Blue_MiSfit]

Cineform lives on It's still quite good and flexible.

x264 can do 4:4:4 encoding now, and 10 bit as well, but I'm not aware of any hardware decoder support whatsoever.