Audio

An Interesting History Of Headphones

k240studioSome time ago I stumbled upon a nice article that proposed to be something of a history of headphones. It’s a fairly good effort on the part of the author. However, I would like to add my two-cents in reference to a couple of missing items that I think are significant.

When I was in school in the mid-1980’s I was studying music recording and broadcasting. I spent a lot of time in and around various recording studios around Toronto. The single most common headset that I saw at that time was the AKG K240 Studio monitors. These were the reference grade dynamic headphones used in many facilities at that time.

The K240s are genuinely, big-ole, cans. A circumaural headphone with a semi-open design they sound great, even today. They can be cleanly driven to excessive volumes if required. Fairly efficient, they can even be powered by a cell phone or iPod.

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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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A Digital Video Compression Primer

Canon XA10 Video CameraIn the post-roll of last week’s VUC call I got into a thread about webcams and various aspects digital video encoding.  While many in the VUC audience already have some understanding of the related principles, it occurred to me that there may be some folks that visit this site who would be interested a primer on the basics of video compression.

Then by some serendipitous twist I found this video on the subject by Drew Tyler, Instructor of Digital Media at Weber State University in Utah. He covers the basics in a pretty good live presentation, even if he is a bit of an Apple fan-boy.

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Auphonic: A Free Online Tool For Automatic Audio Post-Production

auphonic-logoOpen source guru Randal Schwartz of FLOSS Weekly recently interviewed Georg Holzmann of Auphonic.com about their new online service for post-processing audio files for podcasts. Auphonic.com sounds very interesting indeed.

In the past the routine production of the VUC podcasts involved the use of The Levalator from The Conversations Network. That program, while a potent tool, is run locally and limited to processing uncompressed WAV files. This places a certain burden on the user to know how to create the appropriate source files, and later on to encode the processed files for publication online.

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Hey, Mr Podcaster! Audio Quality Matters, M’kay?

ibm-podcast-galaxy-nexus While I travel I like to listen to podcasts. While there are a variety of podcasts that are routinely found on my cell phone, I also try new things from The Conversations Network and similar sites.

This evening as I’m on a flight to Raleigh-Durham NC I happened to give a listen to a short podcast from IBM. It was The IBM Institute For Business Value podcast entitled, “The Changing Face Of Communication.” It’s an older podcast, from June 2009.

While this file had been on my phone a while I had thought that it still might be interesting. IBM certainly knows a thing or two about communications. I was at Astricon 2009 when IBM had a keynote address. They also announced a partnership of some sort with Digium.

However, I was startled to hear the audio quality of this podcast. It’s simply atrocious. Seriously. It’s really bad.

Remember Marshall McLuhan? The medium is the message. In this case the medium, poor quality podcast audio, completely destroys the message…and along with it the credibility of the participants.

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Defining HD Voice vs HD Audio

Earlier today Doug Mohney of HDVoiceNews issued an interesting tweet;

Briefing with Tier 1 telco on #HDvoice. Product manager started using the useless marketing term #HDaudio. Maybe should use #HDtelephony?

I find myself agreeing with Doug’s assertion that “HD Audio” is not appropriate terminology. “HD Audio” is way too broad a term, and more appropriate used with respect to entertainment than telephony.

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