ffmpeg now has some new vulkan filters, but the +vulkan USE flag in the current ebuild that does --enable-vulkan is not sufficient to enable them, as --enable-libglslang is also needed See for example scale_vulkan in the configure file: scale_vulkan_filter_deps="vulkan libglslang" https://github.com/FFmpeg/FFmpeg/blob/master/configure
Apparently there's some weirdness with glslang not supporting pkgconfig. Upstream referred me to reverting commit 98ea1a662ee172961feaa374fe8d26078838d250 as fixing building with --enable-libglslang on debian, and that worked for me on Gentoo as well. Will probably need to be inspected what this does and included as a .patch/some other method to fixup the glslang detection for our specific packaging whenever this gets looked at.
(In reply to Gregory Beauregard from comment #1) > Apparently there's some weirdness with glslang not supporting pkgconfig. > Upstream referred me to reverting commit > 98ea1a662ee172961feaa374fe8d26078838d250 as fixing building with > --enable-libglslang on debian, and that worked for me on Gentoo as well. > Will probably need to be inspected what this does and included as a > .patch/some other method to fixup the glslang detection for our specific > packaging whenever this gets looked at. So as far as I know, a patch that reverts this commit (it just removes a couple things from a line), a dev-util/glslang dependency, and a dev-util/spirv-tools dependency are what's needed here. The spirv-tools dependency isn't obvious, but it's required.