Multitrack Audio Recorder Online

Most likely only one input is ticked. The first device is pre-selected so recording can start in one click; the others have to be ticked by hand. It is easy to check: the number of selected inputs is printed next to the record button, and after the start you get exactly that many tracks. The second cause turns up on laptops: the system offers the same microphone under two names (“Default” and its own), and then two tracks record the same sound. Those duplicates are filtered out of the list, but if two inputs sound identical when you press Test, that is what they are.

That is expected. The browser sees an interface as one device with several channels, not as four separate microphones, and records it as a single stream. Splitting those channels into tracks is not something a browser can do — it happens in the driver or in software with ASIO support. Separate tracks appear here when each microphone arrives as its own device: two USB microphones, a USB mic plus the built-in one, a microphone plus tab audio.

The recorders do not start at the same instant — the browser brings the devices up one after another, and the spread reaches tens of milliseconds. On a single voice that is inaudible; on two microphones in one room it produces a hollow, phasey sound. The start of each track is measured against the audio engine’s shared clock, and the mixdown shifts them back into place. If the spread is significant, the exact figure is shown after you stop. The stems themselves are saved as they were captured, each from its own zero: their offsets are listed in the session text sheet so you can line them up the same way in an editor.

Use the “Tab audio” button next to the microphone list. The browser asks which tab to share — the one with the call — and there you have to switch on “Share tab audio”, otherwise you get a picture with no sound. From then on the guest records onto their own track alongside your microphone. This needs no microphone permission, so you can try it before granting anything. It works in Chrome and Edge; Firefox and Safari do not hand over tab audio, and the button is not shown there.

Everything recorded up to that moment survives. Tracks are written to disk in three-second pieces instead of piling up in the tab’s memory, so a browser crash, a flat battery or an accidentally closed tab costs you the last few seconds at worst. Next time you open the page, that session is offered back for restoring: you can play it and save it. Recordings nobody claims are deleted after a week.

The ceiling is free disk space, not time. Four tracks at 160 kbps use about 290 MB per hour, so a two-hour panel discussion on four microphones is roughly 580 MB. If space is short, that is stated under the input list before you start. In browsers without file storage the take stays in the tab’s memory, and there the sensible limit is tens of minutes — better to stop at natural breaks.