Sunday, October 16, 2016

GST: GPU-decodable Supercompressed Textures

This is amazingly well done:



Check this awesome timeline out:

I no longer feel so alone out here. I've been working on "Supercompressed Texture" technology for about a decade now, before I knew it would be named "Supercompressed Textures". The first title I was involved in that used GPU transcoding of compressed textures was for the PS2 version of World Series Baseball 2k3 (2003). It was designed by Blue Shift's then-CTO, John Brooks. This technology was then licensed to Electronic Arts for use in their PS3 titles.

And, my first Xbox 360 title (Halo Wars) relied on a real-time supercompressed texture decompression system I wrote in '06-'07, so the title would fit into memory at all. (crunch was actually my 2nd attempt at this approach, not my first.) So this tech has been around for years, being used behind closed doors in a low key way. It's like the academic world is just now catching on. In the professional game development world, this is advanced but still "old school" technology now.

My main bit of feedback about this paper, so far: The description of how the selector compression actually works is kinda muddled. (What's the "prefix sum" all about?) Also, it looks like crunch was used at the maximum quality level (255), not a tuned level or a number of levels. Crunch quality level 255 just isn't used in practice, to my knowledge. The codebooks at that level are huge and the image quality is unnecessarily high. Also, can I speed up crunch's CPU transcoder by 2-3x? Oh yes!

Another thing I noticed: Because GST doesn't support lossy endpoint quantization (like crunch does), I think its rate distortion performance is more limited than crunch's. crunch should be able to target lower bitrates than GST, is my guess. GST's main way of controlling the quality vs. rate tradeoff is its lossy dictionary-based selector compression method, while crunch can smoothly vary the quality of both the endpoints and selectors.

Next up: Universal Supercompressed Textures with either CPU or GPU decoding. (Isn't it obvious? We need to abstract away all of these crazy formats behind good technologies and shared tools.)

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