demo · v152 · media capture

Hint vs Default

Run two separately user-mediated captures — one with audioSelection: "preferred", one without — and record what each returned. This is an outcome log, not a controlled proof of hint effect: source choice, audio consent, browser policy, and OS state can differ between runs.

An implementation that does not recognize audioSelection ignores that dictionary member rather than rejecting for that reason, but JavaScript cannot determine whether this happened. To test Chromium's implementation, use a suitable build with chrome://flags/#enable-experimental-web-platform-features or --enable-blink-features=GetDisplayMediaAudioSelection to exercise the real hint. Either way the picker still decides. Use the same source and audio choice across repeated trials before comparing rates; one pair of rows cannot establish causation.

probing…

run	options passed	audio track?	track detail
with hint	`audio:true, audioSelection:"preferred"`	not run	—
without hint	`audio:true`	not run	—

the two calls

// A — with the preference hint
await navigator.mediaDevices.getDisplayMedia({
  video: true, audio: true, audioSelection: "preferred"
});

// B — plain request, no hint
await navigator.mediaDevices.getDisplayMedia({
  video: true, audio: true
});

// Observe track presence; do not attribute one-run differences to the hint.

the two calls

see also