Audio Visualizer

1. “Start Screen/Tab Audio” — best when the browser offers audio sharing

• This button captures sound by sharing your screen or a browser tab together with its audio. In the picker that appears, you must choose “Entire Screen” — or a browser tab that is playing sound — and tick the “Share system audio” / “Share tab audio” box.
• An individual Window never carries an audio track: the share starts, but no sound ever reaches the page. If you picked a Window, press Start again and pick “Entire Screen” or a tab.

2. Firefox on Linux

• Firefox on Linux currently has little to no working support for capturing system or tab audio through screen sharing at all — whatever you pick in the picker, no audio track is handed to the page. This is a Firefox/Linux limitation, not a bug in this page.
• On Linux, Chrome / Chromium / Edge with “Entire Screen” generally work better, depending on whether your desktop supports audio sharing through PipeWire/portal. If it works in one browser and not another, that is why.

3. “Use Microphone / System Monitor” — reliable Linux speaker-audio path

1. Click “Use Microphone / System Monitor” and allow microphone access.
2. Open pavucontrol (PulseAudio Volume Control).
3. Go to the “Recording” tab and find this browser tab’s entry.
4. Change its input from your physical microphone to Monitor of <your output device>.
5. Whatever is playing on the system is now routed into this page as if it were the microphone — in any browser, with no screen sharing involved.

To undo it, set that Recording entry back to your microphone (or just close the tab).