Have you taken a look at the various test harnesses for video encoding/decoding, or consider publishing a standalone one yourself? I get a bit-for-bit rewrite can have some advantage but it's hard to know if the AI implementation actually covers all of the edges cases.

I’m using FFmpeg’s own FATE suite, which is intended to poke at those edge cases, as well as JVT vectors. I’d love to get a more robust set of weird files similar to what symphonia has, though, so if anyone has any resources I’d appreciate it.