You can choose to use an existing
                    html5 audio or video element manually. Simply set the backend
                    option to "MediaElement" and pass the media element as the first
                    argument to wavesurfer.load(). Include an array of peaks as the second
                    argument, the Web Audio API will not be used to render the peaks.
                
var wavesurfer = WaveSurfer.create({
  container: document.querySelector('#waveform'),
  waveColor: '#A8DBA8',
  progressColor: '#3B8686',
  backend: 'MediaElement'
});
// Load audio from existing media element
var mediaElt = document.querySelector('video');
wavesurfer.load(mediaElt);
                    If you have pre-rendered peaks (on your server),
                    you can pass them into the load
                    function. This is optional–if you don't provide
                    any peaks,
                    waserver.js will first draw a
                    thin line instead of a waveform, then attempt to
                    download the audio file via Ajax and decode it
                    with Web Audio if available.
                
// init with an array of peak data.
wavesurfer.load(mediaElt, [0.0218, 0.0183, 0.0165, 0.0198, 0.2137]);
                Press this button to see the same demo with pre-decoded peaks: