- From: guest271314 via GitHub <sysbot+gh@w3.org>
- Date: Thu, 25 Jun 2020 14:49:48 +0000
- To: public-webrtc-logs@w3.org
guest271314 has just created a new issue for https://github.com/w3c/mediacapture-screen-share: == mute and unmute events of MediaStreamTrack should not be fired based on user non-action == The specification uses the term "user activation" exactly once > When the getDisplayMedia() method is called, the User Agent MUST run the following steps: > > If the method call is not triggered by user activation, return a promise rejected with a DOMException object whose name attribute has the value InvalidStateError. The terms "user action" and "user gesture" are not included in the language of the specification. Chromium 85 appears to fire `mute` and `unmute` events on `MediaStreamTrack` from `getDisplayMedia()` directly corresponding to user non-action, for example, not moving the cursor on the captured screen, or user action, moving the cursor on the captured screen. ``` onclick = async e => { var input, recorder, audioTrack, videoTrack, stream, mediaStream, chunks = []; onclick = null; stream = await navigator.mediaDevices.getDisplayMedia({ video: true }); [videoTrack] = stream.getVideoTracks(); videoTrack.onended = videoTrack.onmuted = e => console.log(e); await videoTrack.applyConstraints({ resizeMode: 'none', cursor: 'never', width: window.innerWidth * 0.7, height: window.innerHeight, }); video = document.createElement('video'); video.currentTime = 0; video.autoplay = true; videoTrack.onunmute = videoTrack.onmute = e => console.log(e); video.ontimeupdate = _ => { console.log(video.currentTime, 60 * 7 + 60 * 0.5); if (video.currentTime > 60 * 7 + 60 * 0.5) { recorder.stop(); videoTrack.stop(); } }; video.onplay = _ => { recorder = new MediaRecorder(stream); recorder.start(0); recorder.onstop = async e => { console.log( URL.createObjectURL(new Blob(chunks, { type: 'video/webm' })) ); }; recorder.ondataavailable = e => { if (e.data.size > 0) chunks.push(e.data); }; }; video.srcObject = stream; }; ``` The result is a series of unintended consequences impacting other API's, including media file produced by `MediaRecorder`, `timeupdate` event of `HTMLMediaElement` not firing every 50 to 250ms per HTML Standard. The resulting bugs that have observed so far downstream https://bugs.chromium.org/p/chromium/issues/detail?id=1099280. Kindly include language in the specification which prohibits implementations from firing `mute` and `unmute` events based on user non-action or user action. Please view or discuss this issue at https://github.com/w3c/mediacapture-screen-share/issues/141 using your GitHub account
Received on Thursday, 25 June 2020 14:49:50 UTC