Using the microphone

Instead of using the getUserMedia API with: navigator.getUserMedia({video:true}, onSuccess, onError), it is also possible to use {audio:true} for the first parameter. In this case, only the microphone input will be captured. Notice that {video:true, audio:true} is also accepted; convenient if you want to write a video conferencing system and need to capture both the audio and the video (this is often the case when writing WebRTC applications).

Apart from videoconferencing, microphone input will be used for music Web apps, using the WebAudio API. This API focuses on real time sound processing and music synthesis. You can study it in greater detail in the advanced W3Cx HTML5 Apps and Games.

Check out the WebAudio demonstrations written by Chris Wilson, esp. the one called "Input effects".

The image below is taken from one of the demonstrations, where the sound captured by the microphone is processed in real time. We get visualizations of the signal in real time as an animated waveform, animated frequencies or animated audiogram. If we connect an electric guitar to the sound card input, then this demonstration shows that we can recreate with WebAudio most of the classic effects used by guitarists (delay, reverb, distortion, chorus, etc.).