Skip to content
An experimental music visualizer using d3.js and the web audio api.
Branch: master
Clone or download
Latest commit d2440e2 Jan 14, 2019
Type Name Latest commit message Commit time
Failed to load latest commit information.
css v1.7.0 - fix mic, add audioURL, fastHide, shuffle Mar 28, 2016
icomoon bye musics Nov 16, 2014
img gif wasnt looping Aug 23, 2014
js satisfy chrome autoplay policy changes Jan 14, 2019
mp3 hello new playlist Nov 16, 2014
.gitignore Nicer HUD Aug 19, 2014 changelog 1.7.1 Mar 29, 2016
Gruntfile.js Here goes nothin. Aug 18, 2014 Update Jan 14, 2019
background.js Here goes nothin. Aug 18, 2014
contentscript.js Here goes nothin. Aug 18, 2014
favicon.ico Here goes nothin. Aug 18, 2014
index.html make https-friendly Mar 29, 2016
manifest.json Here goes nothin. Aug 18, 2014

An audio visualizer experiment for the browser. Powered by d3.js and the web audio api. Runs best in Chrome. Working demo @ Try dragging in an mp3 from your desktop!

epilepsy warning

running it locally

There will be issues running this app locally without a server. I recommend cding into the directory and running http-server from the command line. If you don't have this command, install it like so: npm install -g http-server.

a somewhat-technical overview

Using the web audio api, I can get an array of numbers which corresponds to the waveform of the sound an html5 audio element is producing. There's a good tutorial on how to do this. Then, using requestAnimationFrame (with a little frame limiting for performance reasons) I'm updating that array as the music changes. I then normalize the data a bit (or transform it slightly depending on the visualization) and redraw the screen based on the updated array. I'm using d3.js to draw and redraw SVG based on this normalized data. Each visualization uses the data a bit differently -- it was mostly trial and error to get some stuff I liked looking at.

Since I'm using D3 -- which is just drawing SVG -- I was able to style everything in CSS (no images are used at all, including icons). There are a handful of differently colored themes for each visualization, and I do some rudimentary CSS namespacing by updating a class applied to the html element. eg. <html class='theme_1'>. This lets me override or substitute CSS rules pretty trivially. I can add some additional variation to each theme by messing with pseudo selectors. For example, I can use :nth-of-type to hide every nth SVG rectangle or making every odd child have a different stroke-dasharray, etc.

Mousetrap.js handles my keyboard shortcuts brilliantly, and jQuery made life easier.

I developed this primarily in Chrome. Other modern browsers still have some interesting issues (see known issues). I've found that WebKit seems to have the most competent implementation of SVG. And specifically Chrome seems to play the nicest with the html5 audio element. For my purposes at least. Running this can easily strain my four year old MacBook's CPU, but I think I'm pushing several things beyond what they were intended for with this thing. Not complaining.

Markup lies in index.html, javascript is in js/main.js and style in css/style.css. I can go into more detail if there's demand for it.


  • make it a chrome extension -- hijack audio from any page and overlay visualizer. would have to sandbox it in an iframe and then pass audio data into it..
  • make it a chrome app -- since performance seems to be better when files are local
  • auto-detect big changes in song (amplitude deltas / allow rate limiting / average threshold over time if desired) to trigger arbitrary things
  • hook up more 3rd party music service such as spotify / pandora
  • auto detect all mp3s in local folder and display a playlist (chromes webkitRequestFileSystem?)

help & inspiration


cool gifs


Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. For commercial projects, please inquire

You can’t perform that action at this time.