The samples and explanations provided are first rate. They clearly illustrate the merit in ultra-low-latency for some applications, as well as exemplify how CELT currently fares against other common codecs at a variety of bit-rates and with various types of source material.
As someone who’s passionately involved spreading the gospel of HDVoice I’ve been following the mailing list of the IETF CODEC Working Group. They’ve been working towards a new IETF RFC on a brand new wideband codec standard.
Starting with four submissions from Broadvoice, SpiritDSP, Skype and Xiph.org I think that they have made startlingly good progress over the past year. The group has actually arrived at a solution that provides for a codec that is a hybrid of SILK and CELT. It was recently announced on the mailing list that this new hybrid codec is to be known as “Opus.”
At IETF78 in Nagasaki, Japan the working group met to further their efforts. There’s a good recording of the session that, amongst other things, gives considerable detail about the hybrid nature of Opus.
There has been close co-operation between developers at Skype and Jean-Marc Valin of Xiph.org, such that they already have sample code running and have conducted some structured listening tests. The results of the listening tests are reported to be excellent.
It’s very interesting how the hybrid codec works. It can leverage both CELT and SILK principles acting on different frequency bands to generate the most optimal audio for a given bit-rate. It supports a wide range of sample rates from 8 KHz (PSTN narrowband) to 48 KHz (production quality audio) and bit-rates from 8 kbps to 128+ kbps per audio channel.
Opus may have a huge role to play in our transition away from the legacy PSTN. It’s very encouraging to hear that the CODEC Working Group is progressing so quickly.
Earlier today Skype announced the pending launch of a beta program for an SDK called SkypeKit. SkypeKit is intended to allow hardware developers to embed Skype client functionality into their devices.
There’s a bunch of coverage of the SkypeKit launch available at various places online. Engadget has their say and some nice pics of the Grandstream GXV-3140 Media Phone running Skype. Also a Litl webbook that looks like it’s running Skype with video.
Much is being made of the recent events in the IETF CODEC Working Group . Specifically, the fact that Skype has included the c source code for their SILK codec in the Draft RFC document.
Dan York has some excellent coverage including a good general backgrounder on the matter. Jim Courtney has also posted something interesting, as has Phil Wolff of Skype Journal.
A lot of what is being expressed seems to me unbridled enthusiasm for what is seen as a bold, even surprising move on the part of Skype. I agree that this is a gutsy move…and one that I applaud. However, I’m also here to reign in the enthusiasm just a bit. Tempering it with a dose of reality we can see this in a larger context and keep our eyes on the larger goal…ubiquitous wideband telephony.
Here’s the headline:
Zoiper is the First 3rd Party Softphone to Support Skype’s SILK, Polycom’s SIREN and the Broadvoice Codecs
How does that sound? Pretty major, right? Wanna know more? Here are the details.
Given that ZoIPer Communicator is available in web, Windows, Mac & Linux flavors this could jump them to the head of the class for HDVoice support in a soft phone. And of course, ZoIPer Communicator has long supported both SIP and IAX protocols. Yes, you have options. Very nice.
VUC regular Tim Panton has been very busy lately. He was at Astricon where he gave a splendid presentation on the current state of Skype-For-Asterisk, including a live demo of it integrated with Google Wave. He later gave a similar presentation at eComm in Amsterdam, including a demo to the Google Wave team! Of course, we’ve been using his G.722 capable Java plug-in for web browser access to the ZIPDX wideband conference bridge for several months. That has been a genuinely useful bit of software, allowing anyone with a headset & decent broadband to experience HDVoice first hand.