Motion sensing using the Doppler effect

The Doppler effect will be familiar to you if you’ve ever heard an emergency vehicle screaming past you at high speed. As the vehicle approaches the pitch of the sound increases, and as it speeds away, it falls. In this brilliant demo Daniel Rapp uses this effect to perform motion sensing using your computer’s speakers, microphone and the Web Audio API.

A comprehensive scheduling tool for Web Audio

One of the strengths of the Web Audio API is in its support for precision scheduling of events. But you can only schedule audio events on the audio timeline. To synchronise these changes to changes in your user interface, you have to be quite careful. Chris Wilson’s A tale of two clocks blog post shows you how to do this, but helpfully, Sebastien Piquemal has wrapped all of these techniques up in his WAAClock library, which has just reached version 0.5.

Audiocogs: Audio codecs for the web

The Audiocogs team use JavaScript to build decoding libraries for a number of popular audio codecs, including MP3, ALAC, FLAC and AAC. This could be very useful if you want to support user-uploaded file playback, without worrying about whether the browser has the capabilities to play back natively.

Detour hiring OS X engineer in SF to build text-driven audio sequencer

Sponsored post

Detour is a new startup building a platform for location-based audio tours. As part of Detour, they’re building the world’s first text-driven audio sequencer, and are looking for someone to join their team in San Francisco to lead development.

Sonoport Sound Models

At WAC15 Chinmay Pendharkar talked about porting an audio engine from flash to the Web Audio API. They have now released the code for this engine. It has a set of functions for creating sound textures - by looping, triggering, scrubbing and extending audio - as well as some effects. It’s all packaged up in CommonJS and AMD forms.

W3C Multi-device timing community group

If you’ve ever tried to build web applications that require synchronisation of time between multiple devices, you’ll know how hard it is to achieve with the current technology. The W3C MTCG has formed to bring together people and organisations who are interested in solving this problem in a unified way, and you may be interested to join or follow their work if you’re working in this area.

Circles, Sines and Signals: A primer on DSP

A solid knowledge of the techniques and theory of digital signal processing (DSP) is very helpful when working on computer audio. This fantastic collection of articles from Jack Schaedler is a comprehensive, interactive primer covering sampling, aliasing, the Nyquist theorem, Fourier transforms and more. A lot of people sent me this, and I can see why, the interactive diagrams and visualisations are wonderful and inspiring.