audioMotion requires at least Chrome/Chromium 80, Firefox 74 or Safari 13.1.
Playing music and loading backgrounds from your local device relies on the File System Access API, which full specification is currently implemented only on Chromium-based browsers.
This feature should work by default on Chrome, Opera and Edge; on Brave, you’ll need to enable it in chrome://flags/#file-system-access-api (copy and paste it in the address bar).
On Firefox, Fill Opacity may not work properly with Radial analyzer, due to this bug.
Visualization of live streams currently DO NOT work on Safari, as documented in this bug report.