Spectrogram as main view

Hi, sorry to ask this here but I saw your post on the wavesurfer github page and there's not many information about using spectrogram as the main view in wavesurfer.  But I saw in your demo that you're able to make it zoom.  Did you have to create a new drawing canvas for it or can it be done out of the box using wavesurfer.js?

Thank you for your time!