How to render audio waveform on HTML5 canvas? [closed]

Question

I want to render a waveform for an audio file (ogg and/or mp3) to a canvas element.

I was wondering if there were any libraries that would make this simple? I am looking for a result along these lines: http://plucked.de/

Answer 1

https://github.com/katspaugh/wavesurfer.js may be what you're looking for.

Answer 2

If you don't want to download content of the file then waveform image or data must be prepared on server.

Some time ago BBC (yes, UK media company) open-sourced set of tools to do it efficiently. All is described on their blog: http://www.bbc.co.uk/rd/blog/2013/10/audio-waveforms

Shortly: on Linux server-side you have to convert sound file (FLAC, WAV or MP3) to JSON-based waveform interpolation with audiowaveform command-line tool. Next you serve the JSON data to browser client which will render waveform on canvas element with waveform-data.js.