Opus is tricky, it's royalty free but it's not a "free (as in free software)" standard, it's based on Patents held by the likes of Broadcom and MSFT which make them available without royalties.

This is what I've mentioned earlier there are quite a few royalty free but they are still based on held patents which are offered without royalties.

That said honestly I'm not sure how big royalties are HDMI has quite steep royalties DisplayPort doesn't and with pretty much all devices that come with a single/mono-cultured display interface will use HDMI rather than DisplayPort.

Do royalty free patents stop something from being free software? That would be surprising.

Opus' patents have patent retaliation clauses. It would be funny if those were incompatible with the GPL, because the GPL is essentially a "copyright retaliation" license.

We ran the Opus license terms by the FSF before publishing them, and they confirmed that the terms were compatible with the GPL (v3 or otherwise).

Wasn't there an issue with a couple of companies filing IPR's with royalties that cover parts of Opus?

Please see the "Other disclosures" section on https://www.opus-codec.org/license/

You may also be interested in https://hacks.mozilla.org/2013/02/defending-opus/ (warning: contains discussion of specific, unexpired patents).

> I'm really hopeful that one day it will be as successful as Opus.

I assume you mean more successful.

I have never seen or even heard of an Opus file in the wild.

Have you ever used:

- Skype

- Google Hangouts

- Youtube on Chrome

- Mumble

- Teamspeak

- the Playstation 4

- most speech recognition APIs

If so, then you've used Opus.

I think it is quite popular for VoIP and it is also part of WebRTC and hence supported by Chrome and Firefox

https://en.wikipedia.org/wiki/Opus_(audio_format)#Software

As others have mentioned, it's heavily in use in streaming. I don't know that it offers enough of an advantage over vorbis as a file-format to overcome the inertia of devices that support vorbis; we'll see in a few years.

Perhaps here success is a measurement of producing a patent free solution that's technically competitive (performance, compression, other metrics), rather than popular and widely adopted.