Neither Opus nor mp3 have this problem. So to maximize compatibility, mp3 is still the best choice, due to the attitude to Opus and other free codecs that Apple has.
I may be misspeaking about FAAD2, but I've never run into an open-source player (like VLC) or library (like ffmpeg) which hasn't supported at least HE-AAC decode for a decade or more. If that's wrong, I'd love to be corrected in the most detailed way possible.
E.g. for Fedora, it is in rpmfusion repository and not in the distribution proper. Other distributions have similar arrangement for license-os-ok-but-patents-are-problem situation. These servers are outside US (or other countries that recognize software patents), and for the US users, the issue of obtaining the license is up to them.
The situation is so bad, that Fedora stopped shipping support for hardware acceleration of patented codecs (i.e. not complete codecs, but support to use the implementation in hardware, for example in your GPU), because they could be sued for contributory infringement.
Also note, that binaries for VLC or ffmpeg for Windows or Mac are similarly distributed from non-US servers, so basically the same situation as rpmfusion.
Uh, no, this is not correct. If you try to find a source, you'll easily find the opposite is very well established.
Note how AAC has effectively the same efficiency as Opus? HE-AAC and HE-AACv2 are notably better in comparison, and are usable at lower bitrates than AAC.
In cases where "the opposite is very well established", they're talking about AAC-LC. Citations that show otherwise are welcome! In any case, HE-AAC's universality is really beaten only by MP3 (which it trounces).
HE-AAC. Support for HE-AAC and HE-AAC v2 has been universal on modern media platforms and operating systems for well over a decade.¹
BTW, this isn't a "this might just work" comment. I distributed a reasonably-popular podcast (1.2M downloads over its lifetime) using HE-AAC v2 several years ago, and never received a complaint or found a player it didn't work on.¹ I read the other comments recommending Opus before responding, and although Opus is very nice, it's not as efficient or as ubiquitous as HE-AAC.
² https://developer.android.com/guide/topics/media/media-forma...