Zstandard uses finite state entropy (FSE) for entropy encoding (after finding repeats), which in turn us based on asymmetric numeral system (ANS) encoding. The

Zstandard uses finite state entropy (FSE) for entropy encoding (after finding repeats), which in turn us based on asymmetric numeral system (ANS) encoding. The canonical paper on ANS is indecipherable to me (i honestly think it's poorly written, it's not just me, although it is partly me!), but this seems like a clearer explanation (although i still don't entirely get it): https://bjlkeng.github.io/posts/lossless-compression-with-asymmetric-numeral-systems/ https://bjlkeng.github.io/posts/lossless-compression-with-as...