[STREAM-1168] - Pre-negotiate additional video transceiver for multi-track screenshare.

Author: zservies

changelog.md

@@ -4,6 +4,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 # [Unreleased](https://github.com/MyPureCloud/genesys-cloud-webrtc-sdk/compare/v11.5.1...HEAD)
+### Changed
+8 [STREAM-1168](https://inindca.atlassian.net/browse/STREAM-1034) - To support multi-track screenshare + video, added pre-negotiation for an additional `sendonly` video transceiver.
 
 # [v11.5.1](https://github.com/MyPureCloud/genesys-cloud-webrtc-sdk/compare/v11.5.0...v11.5.1)
 ### Added

src/sessions/video-session-handler.ts

@@ -529,13 +529,17 @@ export class VideoSessionHandler extends BaseSessionHandler {
       return;
     }
 
+    // This is the primary video transceiver for the camera
     const videoTransceiver = session.pc.getTransceivers().find(transceiver => transceiver.receiver.track && transceiver.receiver.track.kind === 'video');
     if (!videoTransceiver) {
       session.pc.addTransceiver('video', { direction: 'sendrecv' });
     } else {
       videoTransceiver.direction = 'sendrecv';
     }
 
+    // Pre-negotiate a second video transceiver for screen share to avoid renegotiation later
+    session.pc.addTransceiver('video', { direction: 'sendonly' });
+
     const audioTransceiver = session.pc.getTransceivers().find(transceiver => transceiver.receiver.track && transceiver.receiver.track.kind === 'audio');
     if (!audioTransceiver) {
       session.pc.addTransceiver('audio', { direction: 'sendrecv' });

test/unit/sessions/video-session-handler.test.ts

@@ -1122,27 +1122,37 @@ describe('setupTransceivers', () => {
     expect(getTransceiversSpy).not.toHaveBeenCalled();
   });
 
-  it('should do nothing if video and audio transceivers already exist', () => {
+  it('should only add screen share transceiver if video and audio transceivers already exist', () => {
     getTransceiversSpy.mockReturnValue([videoTransceiver, audioTransceiver]);
     handler.setupTransceivers(session);
 
-    expect(addTransceiverSpy).not.toHaveBeenCalled();
+    expect(addTransceiverSpy).toHaveBeenCalledTimes(1);
+    expect(addTransceiverSpy).toHaveBeenCalledWith('video', { direction: 'sendonly' });
   });
 
-  it('should add video transceiver', () => {
+  it('should add video transceiver and screen share transceiver', () => {
     getTransceiversSpy.mockReturnValue([audioTransceiver]);
     handler.setupTransceivers(session);
 
     expect(addTransceiverSpy).toHaveBeenCalledWith('video', { direction: 'sendrecv' });
-    expect(addTransceiverSpy).toHaveReturnedTimes(1);
+    expect(addTransceiverSpy).toHaveBeenCalledWith('video', { direction: 'sendonly' });
+    expect(addTransceiverSpy).toHaveBeenCalledTimes(2);
   });
 
-  it('should add audio transceiver', () => {
+  it('should add audio transceiver and screen share transceiver', () => {
     getTransceiversSpy.mockReturnValue([videoTransceiver]);
     handler.setupTransceivers(session);
 
     expect(addTransceiverSpy).toHaveBeenCalledWith('audio', { direction: 'sendrecv' });
-    expect(addTransceiverSpy).toHaveReturnedTimes(1);
+    expect(addTransceiverSpy).toHaveBeenCalledWith('video', { direction: 'sendonly' });
+    expect(addTransceiverSpy).toHaveBeenCalledTimes(2);
+  });
+
+  it('should add screen share transceiver for multi-track screen share support', () => {
+    getTransceiversSpy.mockReturnValue([videoTransceiver, audioTransceiver]);
+    handler.setupTransceivers(session);
+
+    expect(addTransceiverSpy).toHaveBeenCalledWith('video', { direction: 'sendonly' });
   });
 });