As far as I can tell, vp9 hardware decoding should be available[0][1], but safari will fallback to software decoding[2]. I can't find much of a definitive source for Apple's supported codecs.

0: https://9to5mac.com/2020/06/24/apple-adds-webp-hdr-support-a...

1: https://en.wikipedia.org/wiki/Apple_M1#Other_features

2: https://trac.webkit.org/changeset/284523/webkit/

VP9 isn’t better than HEVC though is it? And HEVC has hardware encoding and decoding support on most modern devices.

HEVC is loaded with patents. VP9 is Google’s response to avoid the minefield.

The device's hardware encoders/decoders have licenses already. Unless you're shipping your own you're not likely have to pay any royalties. If you're so successful the MPEG-LA comes a' knockin' you should have the money to pay the royalties.

The whole purpose of the MPEG-LA is to be a single entity to approach about licenses held by a bunch of companies. Avoiding paying licenses means avoiding codecs well supported by mobile hardware.

1. For HEVC it's not a single patent pool but many, most of them don't have clearly defined pricing

2. Firefox don't support hevc nor it will be in the future

P.S. https://developer.mozilla.org/en-US/docs/Web/Media/Formats/V... VP9 is supported by all major browsers

Sure, but few devices have VP9 hardware encoding which means re-encoding to view or less efficient software decoding.

You end up with artificially limited numbers of encode streams and stuff with that, at least with nvenc (I think they doubled the limit at the beginning of the pandemic though).