This essay says it's not possible to make a public-domain implementation of Opus. But it could be released under BSD (as libopus is), which is fine for games, as evidenced by the Licenses section of the credits in many games.
That’s going a bit far. I’m in the games industry and have used opus regularly, it’s a great codec for games, often the hardware decoding is so restricted that we’re using software regardless so we might as well use something like opus.
The licensing restriction is unfortunate, but only restrictive for those with very specific goals, under normal conditions BSD is a wonderful license for game devs since you’re free to use the code and only have to add an acknowledgement somewhere.
I suppose a public domain game might hit the same limitation, though as a non-lawyer I would guess the chance of anyone with standing trying to sue anyone implementing from this spec is realistically zero (though I don’t fault stb for being unwilling to roll those dice!)
> under normal conditions BSD is a wonderful license for game devs since you’re free to use the code and only have to add an acknowledgement somewhere.
And it's not as though libopus is an outlier in using a BSD license. A lot of other commonly used libraries have similar licenses; a few examples that come to mind which are likely to show up in games are zlib, curl, Lua, and SDL.
[−]chaosharmonic · 2026-07-01 Wed 21:38 UTC ·
link
libopus isn't even an outlier in using it for a media format specifically. See: everything coming out of the Alliance for Open Media
Most games use the sound support that comes with their game engine or choice of sound system, so I don't think the lack of an STB version is an issue. Performance is more of a problem. Audiokinetic, the makers of the popular Wwise audio system, estimate that Opus takes ~3-5x the CPU of Vorbis:
He's definitely being way over pedantic. Reading the law like HN programmers imagine it works, rather than how it actually works.
The intent of the legal language in that spec is pretty clearly that you have to use the BSD license if you copy that code, but if you merely read it to understand the spec then you don't.
https://nothings.org/stb/stb_opus.html
This essentially causes opus to never be used in games or in things in stores that may have issues with specific licenses.
The licensing restriction is unfortunate, but only restrictive for those with very specific goals, under normal conditions BSD is a wonderful license for game devs since you’re free to use the code and only have to add an acknowledgement somewhere.
I suppose a public domain game might hit the same limitation, though as a non-lawyer I would guess the chance of anyone with standing trying to sue anyone implementing from this spec is realistically zero (though I don’t fault stb for being unwilling to roll those dice!)
And it's not as though libopus is an outlier in using a BSD license. A lot of other commonly used libraries have similar licenses; a few examples that come to mind which are likely to show up in games are zlib, curl, Lua, and SDL.
https://www.audiokinetic.com/en/community/blog/a-guide-for-c...
The intent of the legal language in that spec is pretty clearly that you have to use the BSD license if you copy that code, but if you merely read it to understand the spec then you don't.