cross-browser getUserMedia shim with node.js style error-first API.

Downloads in past


1.0.19 years ago11 years agoMinified + gzip package size for mediastream-gain in KB



What is this?

A tiny browser module for creating a gain/volume controller for the audio channels in a MediaStream.
It's useful for controlling the volume of your microphone input before it's sent accross a peer connection in a WebRTC call, for example. This module is a small part of SimpleWebRTC where it is used for minimizing echos, by using hark to determine if you're speaking and turning your mic down a bit if you're not.
This module is suitable for use with browserify/CommonJS on the client.
If you're not using browserify or you want AMD support use mediastream-volume.bundle.js.

Important details

The way this works by replacing the first audio channel in the stream with one that is run through a gain filter. But beware that this edits the stream you give it in place it doesn't produce a new one.


npm install mediastream-gain

An example

Here we use another piece of SimpleWebRTC getusermedia to fetch user media in a cross-browser, easy-to-handle-errors-and-lack-of-support sort of way.
This assumes a commonJS environment, but that's not a requirement (see above).
var MicGainController = require('mediastream-gain');
var getUserMedia = require('getusermedia');
var gainController;

getUserMedia(function (err, stream) {
    // this will replace the audio channels in the 
    // stream
    gainController = new MicGainController(stream);
    // set gain to 20%
    // set gain to 0, effectively muting it
    // there's also:; // equivalent to setGain(0)
    gainControl.on(); // equivalent to setGain(1)


It couldn't be simpler, but behavior varies slighly based on availability of WebAudio support that can be wired into WebRTC.
You can check for support by checking the support property of the an instance of gainController
These will simply be noop functions if WebAudio isn't fully supported.
.setGain(Float) - takes a number between 1 and 0 .getGain() - returns current setting .off() - shortcut for turning mic off .on() - shortcut for full gain



Created By

If you like this, follow: @HenrikJoreteg on twitter.