Curious what your issue is with it -- it basically says "if you dont sue us, we wont sue you". Thats about as good as I can expect from a large tech company these days with regards to patents.
If Facebook wanted zstd in the browsers, which would make sense for them to be able to reduce bandwidth and improve performance, the patent grant seems to make that impossible: Google would never put zstd in Chrome with such a clause.
I don't understand these things well. But if true this would be really bad. LZ4 is everywhere because it was completely free and I think most of Zstandard's real work was pre-facebook by just Yann alone. Now to have its hand tied because of his job at facebook is the worst thing possible.
I just read the Opus patent summary. It seems like if zstd followed the same license using it wouldn't give facebook any license but if I sue facebook I loose the licese to use zstd. Am I correct in that.
Well, I suppose so, provided that you hold patents and want to use them offensively.
Because as far as I can see, Facebook has an exception saying that if they for some reason patent-sue you first, you would be allowed to countersue without losing your license to their patents.
That could be a misinterpretation, I suppose. But if it's right, then Facebook's license seems superior for those parties who wish to end software patents.
Facebook's license seems superior for those parties who wish to end software patents
It's mostly superior for Facebook. If you're a party that wants to end software patents, but intends to use zstd in any place you might want to interface with a company that doesn't hold the same position, then you're screwed.
If you want to end software patents, and Facebook sues with one (not applying to zstd), you're also still screwed. This is relevant because even if you're against software patents, you can take them out defensively. But this license makes that useless.
Compare to GPL vs LGPL, or how the free software codecs all eventually moved to BSD.