Wideband

Topics relating to wideband telephony, aka. HDVoice or HDComms

Blink Does Opus

Blink-Yeti-OpusLast week there was some exciting news on the AG Projects mailing list; Blink support for the Opus codec was being released for the Mac version of Blink. A similarly capable release of the Windows version was expected shortly. Earlier this week Adrian Georgescu, the A. G. of AG Projects, passed me a Blink for Windows release candidate for experimental use.

This beta release installed readily, right along side the production release. I quickly registered it with my account at SIP2SIP.INFO so that we could have a couple of brief test calls.

Since most telephony oriented audio hardware doesn’t do justice to full-bandwidth audio I connected my Blue Microphones Yeti USB Microphone and a pair of AKG K 240 Semi-Open Studio Headphones . It seems that the team at AG Projects have also settled on the Yeti as a very good, yet affordable choice for high-quality sound pickup.

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Audio Codes Offer First Signs Of Hardware Support for Opus Codec

AUDIO-CODES-420HD-300pxOne of the first interesting things to arise out of this weeks WebRTC conference in Atlanta is an announcement from Audio Codes that they will be adding support for the Opus codec to their 400HD series of SIP desk phones. Here’s the press release.

There seems to be a little confusion about what’s actually going to be offered.  The title of the release states, “AudioCodes Announces WebRTC Phone.” The copy goes on to describe that the hardware will be extended to provide native support the Opus codec. This capability is projected to be deliverable in Q4-2013.

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Freeswitch En Route To Support For G.719 Codec

VVX_1500_D_Freeswitch.jpgThink back to the handful of new audio codecs that have been released over the past few years; CELT, SILK and Opus to name a few. Then there are the handful of proprietary codecs that have become available under more attractive licenses. Polycom’s Siren family come to mind on that front. In all of these cases I have observed that the Freeswitch development team are typically amongst the very first to implement any new codec.

In recent weeks they have added support for G.719, an ITU standard codec created by Polycom and Ericsson. With a  sample rate of 48 KHz, G.719 is a full-bandwidth codec, supporting a useful audio channel of 20 Hz- 20 KHz. It does so with end-to-end delay of only 40 ms and at bit rates from 32 kbps to 128 kbps. It also supports stereo audio.

Upon completion of the ITU standards process Polycom published a white paper on the codec; G.719: The First ITU-T Standard for Full-Band Audio (pdf).

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Experimenting with Opus I: PhonerLite

Opus-LogoInspired by my earlier interaction with Mike Phillips I thought it would be interesting to get some hands on experience with Opus. It would be worthwhile staging a little test to better understand the audio path presented in one or more Opus implementations.

A quick Google search revealed that PhonerLite, the freeware Windows soft phone from Germany, includes Opus from the v1.92 release onward. According to the release notes support for Opus replaced support for CELT. The current release is v2.08 from April 16, 2013.

I had first encountered PhonerLite some time ago, when I was seeking a G.722 capable soft phone. It’s very functional but a bit quirky.

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Considering Opus Implementations

Opus-over-skypeOpus promises to be a great tool for online audio. In technology, as in music, not all opus are implemented equally. Allow me to explain.

Earlier this week I happened into a Twitter exchange with Mike Phillips. Mike is a podcaster. VUC founder Randy Resnick has introduced us once before. Mike is seeking a replacement for the role that Skype plays in his online toolbox.

It came to light that Mike has tried to leverage various soft phones, even giving some focus to finding one that implements the Opus codec. Opus is after all, open source, the current state-of-the-art in audio codecs, and a new IETF standard. However, in Mike’s attempts to tap its potential he has to date come up short relative to Skype.

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