AMD Updates Mesa Video Driver Code With Geometric Scaling & HLG

[phoronix]

Phoronix: AMD Updates Mesa Video Driver Code With Geometric Scaling & HLG

AMD has merged updated video processing engine "VPElib" code into their Mesa driver with their latest feature work...

https://www.phoronix.com/news/AMD-VPElib-Mesa-Geo-HLG

[Quackdoc]

Looks like there is also some PQ work here, which is IMO significantly more important then HLG is

[chrisr]

Am I correct that this "VPElib" is only relevant for RDNA3 cards with a VPE? Seems likely, yes?

[QwertyChouskie]

I'm tellin y'all, a Steam cloud gaming service is coming, mark my words.

[plonoma]

What's PQ and what's geometric scaling about?

[Quackdoc]

What's PQ and what's geometric scaling about?

PQ/HLG are transfer functions.the TLDR is basically humans don't see light intensity linearly, because of this if we wanted to store "linear light" it would be super expensive. so you use PQ/HLG to "shape" the intensity of light. you can find a more indepth explanation in the first part of this post https://quackdoc.github.io/blog/hidden-jxl-benefits/

Geometric scaling is a... strange term but the description for it is in the file itself

* Geometric scaling is to support multiple pass resizing to achieve larger resize ratio.
* User will need to set stream.flags.geometric_scaling = 1
* With the gs flag set to true, VPE will disable following feature
* 1. gamma remapping, the input tf will be used for output tf.
* 2. gamut remapping, the input primiaries/range will be used for output.
* 3. tone mapping, tone mapping will be disabled.
* 4. blending, blending will be disabled.
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