The first issue I have found trying to build a video editor on the web.
I have multiple video streams (desktop and web cam) and I wanted to be able to
toggle between the video streams on one video element so that I can quickly
switch between the web cam and the desktop and not break the MediaRecorder
.
It looks like you should be able to do it via toggling the selected
property
on the videoTracks
object on the <video>
element, but you can't, the array
of tracks contains only 1 element (the first video track on the MediaStream).
What steps will reproduce the problem? (1) Get two MediaStreams with video tracks (2) Add them to a new MediaStream and attach as srcObject on a videoElement (3) Check the videoElement.videoTracks object and see there is only one track
Demo at https://multiple-tracks-bug.glitch.me/
What is the expected result? I would expect videoElement.videoTracks to have two elements.
What happens instead? It only has the first videoTrack that was added to the MediaStream.
Repro case.
window.onload = () => {
if('getDisplayMedia' in navigator) warning.style.display = 'none';
let blobs;
let blob;
let rec;
let stream;
let webcamStream;
let desktopStream;
captureBtn.onclick = async () => {
desktopStream = await navigator.getDisplayMedia({video:true});
webcamStream = await navigator.mediaDevices.getUserMedia({video: { height: 1080, width: 1920 }, audio: true});
// Always
let tracks = [...desktopStream.getTracks(), ... webcamStream.getTracks()]
console.log('Tracks to add to stream', tracks);
stream = new MediaStream(tracks);
console.log('Tracks on stream', stream.getTracks());
videoElement.srcObject = stream;
console.log('Tracks on video element that has stream', videoElement.videoTracks)
// I would expect the length to be 2 and not 1
};
};
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