Screen + audio is the default mode. The video comes from getDisplayMedia; microphone sound comes from getUserMedia. If both live audio tracks exist, Web Audio produces one mixed track for MediaRecorder.
How to use it
- Choose Screen + audio and enable the audio sources you need.
- Choose your folder, start, and approve each browser request. In the display picker, explicitly share audio when available.
- Verify the microphone and shared-audio indicators. If shared sound is missing, stop and select a supported source again.
Limits and safety
A checked Shared audio option requests sound but cannot force the browser to supply it. If the microphone remains available, recording can proceed with a warning and microphone sound only. The muted preview is intentional; verify the saved file for a real audio test.
References
Check the result, not just the controls
A practical test
For a lesson with narration and page sound, test the two sources separately first, then together. A moving picture does not prove that either audio track exists. Headphones can reduce acoustic feedback, but cannot create a shared-audio track the browser did not grant. If the saved sample lacks one source, fix the picker or microphone selection before recording the lesson.