WebRTC : How to determine if remote user has disabled their video track?

In WebRTC, when a remote user disables their video track, we can determine this behavior by listening to specific events and checking the properties of the media tracks. Specifically, the following steps can be implemented:

1. Listen to the track event

When a new media track is added to the connection, RTCPeerConnection triggers the track event. We need to set up an event listener to handle this event.

javascript
peerConnection.ontrack = (event) => {
    console.log('New track added:', event.track);
    handleTrackEvent(event.track);
};

2. Check the enabled property of the track

Each media track (MediaStreamTrack) has an enabled property that indicates whether the track is currently transmitting media data. If the user disables the video, this property is set to false.

javascript
function handleTrackEvent(track) {
    if (track.kind === 'video') {
        console.log('Video track status: ' + (track.enabled ? 'enabled' : 'disabled'));
    }
}

3. Listen to mute and unmute events

Media tracks also trigger mute and unmute events, which can be used to further confirm the track's status. When the track pauses sending data, the mute event is triggered, and when it resumes sending data, the unmute event is triggered.

javascript
track.onmute = () => {
    console.log('Track has been muted.');
};

track.onunmute = () => {
    console.log('Track has been unmuted.');
};

Practical Application Example

Assume we are developing a video conferencing application, we need to monitor the video status of participants in real-time to provide a better user experience. For example, when a user disables their video, we can display a default avatar in their video window or notify other participants that the user currently has no video output.

Summary

By following these steps, we can effectively detect and respond to a remote user disabling their video track in a WebRTC session. This is crucial for ensuring good communication quality and user experience.