Opus

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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Confirming The Quality Of One’s Tools

Zoom-H2-Nexus7-AudioTool.jpgWhen experimenting with a new audio path I like to take measurements. Long ago, in an age of techno-pre-history known as the late 1980’s,  I craved what were then an emerging class of computerized test instruments, like the Audio Precision System One. Happily, today such costs are unwarranted given the current class of programmable smart devices. I’ve been very happy with Audio Tool For Android running on my Nexus 7 tablet.

If I am to trust the measurements that Audio Tool allows me to make I need to start by confirming the validity of it’s measure using a known reference signal. I was also making use of the Zoom H2 Handy Portable Stereo Recorder, so I decided to record the output of the sweep generator in Audio Tool to the H2. Then I tool the resulting WAV file into Adobe Audition to see what resulted.

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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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