The Myousica multitrack: audio mixing in the browser

Sat, 16 Oct 2010 00:00:00 +0000

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2026 retrospective
For the big picture — why Myousica was ahead of its time and who does it today — see the 2026 retrospective.

This is the second post in the Myousica series. The first one covered the Rails platform. This one dives into the multitrack editor — the Flash/Flex component where users actually mix music in the browser.

The multitrack was initially developed by Vaclav Vancura, who built the original architecture, the UI component library, and the audio playback engine. I then took over and rewired it heavily — integrating recording, upload, the backend services, and the state machine that holds it all together. 81 ActionScript files, ~7,300 lines of code, 129 commits.

Here’s Vaclav’s original screenshot showing the remix view — where songs connect and branch into new remixes:

What it does¶

The editor loads in the browser as a Flash SWF. You can:

Load up to 16 audio tracks simultaneously
Play them all in sync with a single transport
Adjust per-track volume and balance
Record your own track from the microphone, synchronized to the playback
See waveforms for every track
Search for tracks to add to your mix (via the Rails API)
Save and publish the result

All of this happens client-side in Flash Player 9, with the heavy lifting (encoding, storage) offloaded to the backend services.

The dimensions¶

Everything is pixel-precise. The editor runs in a 690px wide stage with fixed proportions:

Actionscript on Marcello Barnaba

The Myousica multitrack: audio mixing in the browser

What it does¶

The dimensions¶