On the mailing list of the IETF’s CODEC working group Jean-Marc Valin made a significant announcement on Feb 4th. It reads as follows:
We’d like to announce that the Opus codec is now ready for testing. The bit-stream is now is a “pseudo-freeze”, which means that unless a problem is found during testing/review, there are no longer any changes planned. The only exception to this are the SILK-mode FEC and the stereo SILK mode, which should be landing in the next few days. Considering that these are not critical features, we felt like the testing phase could already begin.
Please recall that OPUS is the new codec arising from the combination of CELT and Skype’s SILK. It’s multiple operating modes accommodate many different applications, from extremely low-latency high-quality links between production studios, to voice applications on very low bit-rate channels. OPUS brings us the current state-of-the-art in audio codec technology in a royalty-free, open source form.
Even so, a codec alone is of little use without applications that permits its implementation in a practical manner. Happily, there are people like Anthony Minessale of Freeswitch fame. Anthm read Jean-Marc’s message and within just a few short hours had an implementation checked into the Freeswitch GIT repository.
Since Freeswitch already handles many sample rates, easily up to 48 kHz, it provides an excellent framework for testing OPUS. The Freeswitch web site has examples of using the application as an end-point as well as a switching system. You can even run Freeswitch as an installable module on a pfsense edge router.
I look forward to reading more about OPUS as a broad group of people experiment with its use. I wish that I had some time to experiment myself, but alas my work schedule will keep me from such things for the next month or two.
In other news, the Freeswitch project managed to get their .com domain back. And I’ve decided to be more restrained and not use the picture of Berkeley Breathed’s Opus character when referring to the new IETF codec.