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> The thing I'm really surprised about is that you still can't use arithmetic coding with JPEG.

I was under the impression libjpeg added support in 2009 (in v7). I'd assume most things support it by now.

Believe it or not, last I checked, many browsers and some other software (file managers, etc.) still couldn't do anything with JPEG files that have arithmetic coding. Apparently, although I haven't tried this myself, Adobe Photoshop also specifically doesn't support it.

Arithmetic coding decodes 1 bit at a time, usually in such a way that you can’t do two bits or more with SIMD instructions. So it will be slow and energy inefficient.

this isn't necessarily true. zstd uses an ans which is a type of arithmetic coding which is very efficient to decode

Nice to learn about. It’s good to know the field has progressed, however the context focused on JPEG, where my point does apply.

Deompression is limited by memory bandwidth IME, which means that more efficient compression is (almost) always more power-efficient too.

(I don't have numbers for this, but it was generally agreed by the x264 team at one point.)

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