Loopback audio capture
Loopback audio capture is the technique of recording the audio a computer is already playing — such as the voices in a video call — by reading the operating system's output stream directly, rather than through a microphone or a third-party meeting bot.
Last updated June 9, 2026
Loopback audio capture is the technique of recording the audio a computer is already playing — such as the voices of remote participants in a video call — by reading the operating system’s output stream directly, rather than through a microphone or a third-party meeting bot.
How it differs from a microphone
A microphone records sound in the room: your own voice, background noise, and whatever the speakers play back — degraded and echoey. Loopback capture instead taps the clean digital stream the operating system is already sending to your speakers or headphones. For a video call, that stream carries the other participants’ voices exactly as they were transmitted: clear, and with none of your room’s noise mixed in.
How it works on each platform
Loopback capture is a feature of the operating system’s own audio stack, not an add-on:
- Windows — the Windows Audio Session API (WASAPI) exposes a loopback mode that lets an app read the audio being rendered to an output device.
- macOS — recent versions (macOS 14.4 and later) provide a Core Audio process-tap API, so an app can capture system or per-app audio without installing a third-party driver. Older versions generally required a virtual audio device.
- Linux — PulseAudio and PipeWire expose “monitor” sources that mirror an output device’s stream.
Why it matters for meeting notes
Because loopback capture reads audio that is already playing, a meeting tool can listen to a call without joining it as a bot, installing a browser plugin, or — on current operating systems — adding a virtual audio device. That is the mechanism behind bot-free meeting notes: there is no extra attendee in the call, and the audio is processed through system audio capture on your own machine. Canary uses loopback capture to feed its streaming transcription and its live, rolling summary.
Loopback capture vs. a virtual audio device
Both can record system sound, but a virtual audio device — a software loopback driver you install — has to be added and routed manually, and it can disrupt your normal playback. Native loopback capture uses the operating system’s own APIs, so there is nothing extra to install or configure. See how to record system audio on a Mac without a virtual device for the practical version.
A note on consent
Capturing a call should always be transparent, never secret. Recording-consent laws vary by region — some require only one party’s consent, others require everyone’s — so tell participants when you are capturing a meeting. See how to take meeting notes without a bot for the responsible approach.