Draw audio waveform to a canvas using the Web Audio API
This is a small helper module that allows you to render a canvas to visualize audio from an audio or video element, or a getUserMedia stream. It uses the Web Audio API. This can be useful to display audio visually, or to track down when a video or audio element does not behave as you expect.
This was primarily written to work with the rtc-media library so here's an example of how it works there:
var media = require'rtc-media';var waveform = require'rtc-audio';var localvideo = media;var videoElement = localvideorenderdocumentbody;var canvas = waveformvideoElement "stream" : localvideo;
This example shows how to pipe an audio file into the waveform display. The canvas will be added to the body element unless you provide a different element to attach it to.
var waveform = require'rtc-audio';var audio = 'examples/media/Hydrate-Kenny_Beltrey.ogg';var canvas = waveformaudio "play" : true;audioplay;
This example shows how to create a waveform display for a video element. It also shows how to attach the waveform to a separate element.
var waveform = require'rtc-audio';var body = documentgetElementsByTagName'body'0;var div = documentcreateElement'div';var video = documentcreateElement'video';videosrc = 'examples/media/sintel_trailer.webm';videocontrols = 'controls';bodyappendChilddiv;bodyappendChildvideo;var canvas = waveformvideo "play" : true "attach" : div ;videoplay;
- target : media element or Audio instance
- width : the width of the canvas
- height : the height of the canvas
- stream : if you're using WebRTC, you need to hand in the MediaStream directly
- play : if set to true, also route the audio to the output device
- attach : element to which the canvas will be added as a child
You can use beefy to run the examples, e.g.
$ beefy examples/rtc-media.js
Copyright 2013 National ICT Australia Limited (NICTA)
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