WebRTC ontrack how to tell if it is a screen sharing session? - webrtc

Question

function OnTrack(e) {
if (e.track.kind === "audio") {
}
else if (e.track.kind === "video") {
}
// Screen Sharing e.track.kind === 'video'
};
In the code above we can distrigush between Audio / Video. But how can I tell if the Video stream is actually coming from a screen sharing session?

Answer 1

Modify the SDP
Found a workaround, by modifying the SDP. I hope someone can come out with a better solution than this.

Answer 2

The getSettings() method contains the properties of the track, including cursor, displaySurface, logicalSurface which are only present on a screen sharing track.
With displaySurface as an example:
function OnTrack(e) {
let settings = e.track.getSettings()
if (e.track.kind === "audio") {
}
else if (e.track.kind === "video") {
if (settings.displaySurface && (
settings.displaySurface === "application" ||
settings.displaySurface === "browser" ||
settings.displaySurface === "monitor" ||
settings.displaySurface === "window")) {
// Screen Sharing
}
}
};
The values of displaySurface are application, browser, monitor, window.
You can also get displaySurface from the getConstraints() method of the track.
Update
It turned out you need to add these constraints/settings when you are calling the getDisplayMedia(constraints):
These constraints apply to MediaTrackConstraints objects specified as
part of the DisplayMediaStreamConstraints object's video property when
using getDisplayMedia() to obtain a stream for screen sharing.
Note from the MDN page
Not all user agents support all of these surface types.
More information
MediaStreamTrack getSettings()
MediaTrackSettings
MediaTrackSettings DisplaySurface
MediaStreamTrack getConstraints()
MediaDevices getDisplayMedia()