I would be interested in seeing the ability to add audio tracks to the timeline in the Sozi interface, and willing to contribute to its development.
Have you contemplated this option before? I understand it may be difficult, but it would really take the app to the next level.
I have been using the app for creating process walk through's because the html/svg presentation is perfect on any device. I currently pop up explainer text, but audio would be better. And the current implementation of audio is, well..., buggy. And I think with HTML5, a better implementation may be possible.
Your work is terrific!