Making the rav1d Video Decoder 1% Faster

Making the rav1d Video Decoder 1% Faster *on macOS with an M3 chip *slightly more than 1%, on a specific benchmark, without any new unsafe code A while ago, memorysafety.org announced a contest for improving performance of rav1d , a Rust port of the dav1d AV1 decoder. As this literally has my name written on it, I thought it would be fun to give it a try (even though I probably can’t participate in the contest). This is a write-up about two small performance improvements I found (1st PR, 2nd PR) and how I found them (you can also jump to the summary in the end). Background and Approach rav1d is a port of dav1d , created by (1) running c2rust on dav1d , (2) incorporating dav1d ’s asm-optimized functions, and (3) changing the code to be more Rust-y and safer. The authors also published a detailed article about the process and the performance work they did. More recently, the contest was announced, with the baseline being: Our Rust-based rav1d decoder is currently about 5% slowe ... Read full article.