This is exactly the kind of thing I would've been working on if my boss hadn't said "it's a great idea, but let's just use it if somebody else does it". I worked on converting JSMad to use entirely typed arrays last summer (fun!), so I'm especially glad to see that all fixed up in the refactoring for Aurora.

Now, what I'd really like to see is a similar project for a) container formats and b) video codecs. I've been experimenting with using JSMad to display waveforms from decoding MP3 files that are the audio tracks of videos (for assisting with subtitling), but it's kinda annoying having to download a separate file for generating waveforms rather than just extracting it directly from the same video that's playing anyway.