@lizzy

Okay so…you’re doing planar output. And Vulkan. And YUV color space?

This is very confusing to me. Especially the planar part.

@rk yes…

the YUV color space is the smallest problem, i can just convert between rgb and yuv easily, the problem is really the planar format

if a 4x4 RGB image is this:

a 4x4 NV12 image is like this:

where each UV value corresponds to two vertically adjacent Y values

initially i missed this fact and thought it was a 1:1 UV <-> Y correspondence, which is why i considered multiple color attachments

@lizzy

So…I guess I missed the overarching context here. What are you doing that has planar graphics?

@rk it’s… related to the video processor MFT, which is a windows api to convert images (or streams of images, for deinterlacing, but that’s not relevant here) between different formats and/or crop, rotate etc. them… it’s a bit like imagemagick on crack

I’m dealing with a game that wants the output to be NV12

@lizzy

Ah. You’re well beyond my expertise in this area then. If you were needing to deal with planar modes on an Amiga or with ILBMs (which I guess could actually be relevant?) I could help, but otherwise I’m well out of my bitdepth.

@lizzy

Ah. You and I are about forty years out of sync. I definitely need to catch up but, if you’re interested in how we dealt with memory bandwidth limitations the original planar modes on the Amiga (and similarly vintaged systems) some spelunking might be fun.

@lizzy

I am only casually interested in the N64, but it comes from an era where these sorts of things really mattered because you were designing your own bus/architecture.

Also, randomly, do you know @mothcompute ? If not, lemme introduce y’all. You’re both way smarter than I am at these sorts of low-level details and I would enjoy watching y’all nerd out.

@mothcompute @lizzy

(Obligatory “See MIPS Run” is the best CPU architecture book ever comment.)

@mothcompute @lizzy

(You both need to nerd out *here*. I’ve already done the Twitter migration. I’m not going to BlueSky too. I’m too old and tired.)

@puppygirlhornypost2 @mothcompute @rk

unlike here with my 100,000 character limit i am restricted and forced to split my paragraphs into like 5 individual replies

the funny thing is I am anti character limit but you’re one of the few people who sometimes makes me consider that it could be a good idea