One shot signalling mode fixes (#3223)

* set desired on synchronous track

* debug

* debug

* direction

* reuse

* clean up

pkg/rtc/mediatracksubscriptions.go

@@ -309,6 +309,7 @@ func (t *MediaTrackSubscriptions) AddSubscriber(sub types.LocalParticipant, wr *
 	//   but it is not detrimental to set this, needs clean up when participants modes are separated out better.
 	subTrack.SetNeedsNegotiation(!replacedTrack)
 	subTrack.SetRTPSender(sender)
+
 	// it is possible that subscribed track is closed before subscription manager sets
 	// the `OnClose` callback. That handler in subscription manager removes the track
 	// from the peer connection.

pkg/rtc/participant.go

@@ -2954,6 +2954,10 @@ func (p *ParticipantImpl) SupportsSyncStreamID() bool {
 }
 
 func (p *ParticipantImpl) SupportsTransceiverReuse() bool {
+	if p.params.UseOneShotSignallingMode {
+		return p.ProtocolVersion().SupportsTransceiverReuse()
+	}
+
 	return p.ProtocolVersion().SupportsTransceiverReuse() && !p.SupportsSyncStreamID()
 }
 

pkg/rtc/subscriptionmanager.go

@@ -645,6 +645,7 @@ func (m *SubscriptionManager) subscribeSynchronous(trackID livekit.TrackID) erro
 		m.subscriptions[trackID] = sub
 	}
 	m.lock.Unlock()
+	sub.setDesired(true)
 
 	subTrack, err := track.AddSubscriber(m.params.Participant)
 	if err != nil && !errors.Is(err, errAlreadySubscribed) {