Not just C, dav1d and dav2d are actually mostly written in ASM! Then there's a bit of C as the glue or for functions that don't have optimized ASM yet.

Since dav2d is newer it has a higher fraction of C, but not enough for it to be the main language in the codebase :)

for dav1d there is https://github.com/memorysafety/rav1d although it reuses the dav1d assembly and performance is typically slower by a single-digit percentage.

What are you even implying?