What image do you display when you need to uniquely and visually represent an audio file, in a similar way to using thumbnails for photos and videos? Learn how

What image do you display when you need to uniquely and visually represent an audio file, in a similar way to using thumbnails for photos and videos? Learn how to generate waveform images on-the-fly from uploaded audio files using dynamic URLs. Sample code included for Javascript, PHP, Rails, Node.js and more.