Hi everyone!

Hashing for fixity and transfer-checking seems to be quite a bottleneck for archiving big video/film files for archiving.

Therefore I was considering if using "simpler" algorithms (like CRC instead of SHA256) could speed up the process. I was surprised that e.g. MD5 vs CRC in Python as well as PHP seemed to be equally "fast".

So I was wondering:
Does FFmpeg have/do any speed optimization for hashing functionality (framemd5, hash muxer, etc) in its code?

I've noticed, for example that "-f hash" for MD5 uses only half, SHA256 just a quarter of my CPU. Input source was H.264/AAC/MP4, which I guess decodes multi-threaded?

I'd be very grateful if anyone's interested to provide me some insights or ideas in how FFmpeg's hashing could be made faster.

Thank you very much in advance,
Peter B.

I also found a possibly related claim in a Stackoverflow answer that the hashing functions are not implemented as fast as they could be:
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