refactoring, enabling sending out room updates

2026-03-30 22:05:39 +00:00 · 2020-12-01 23:32:15 -08:00
parent 0c99163253
commit a6c4db2cb3
12 changed files with 480 additions and 248 deletions
--- a/cmd/cli/client/client.go
+++ b/cmd/cli/client/client.go
@@ -18,7 +18,6 @@ import (

 	"github.com/livekit/livekit-server/pkg/logger"
 	"github.com/livekit/livekit-server/pkg/rtc"
-	"github.com/livekit/livekit-server/pkg/service"
 	"github.com/livekit/livekit-server/proto/livekit"
 )

@@ -203,7 +202,7 @@ func (c *RTCClient) Run() error {
 			// send the offer to remote
 			req := &livekit.SignalRequest{
 				Message: &livekit.SignalRequest_Offer{
-					Offer: service.ToProtoSessionDescription(offer),
+					Offer: rtc.ToProtoSessionDescription(offer),
 				},
 			}
 			c.AppendLog("connecting to remote...")
@@ -215,7 +214,7 @@ func (c *RTCClient) Run() error {
 		case *livekit.SignalResponse_Answer:
 			c.AppendLog("connected to remote, setting desc")
 			// remote answered the offer, establish connection
-			err = c.PeerConn.SetRemoteDescription(service.FromProtoSessionDescription(msg.Answer))
+			err = c.PeerConn.SetRemoteDescription(rtc.FromProtoSessionDescription(msg.Answer))
 			if err != nil {
 				return err
 			}
@@ -231,12 +230,12 @@ func (c *RTCClient) Run() error {
 		case *livekit.SignalResponse_Negotiate:
 			c.AppendLog("received negotiate",
 				"type", msg.Negotiate.Type)
-			desc := service.FromProtoSessionDescription(msg.Negotiate)
+			desc := rtc.FromProtoSessionDescription(msg.Negotiate)
 			if err := c.handleNegotiate(desc); err != nil {
 				return err
 			}
 		case *livekit.SignalResponse_Trickle:
-			candidateInit := service.FromProtoTrickle(msg.Trickle)
+			candidateInit := rtc.FromProtoTrickle(msg.Trickle)
 			c.AppendLog("adding remote candidate", "candidate", candidateInit.Candidate)
 			if err := c.PeerConn.AddICECandidate(*candidateInit); err != nil {
 				return err
@@ -314,7 +313,7 @@ func (c *RTCClient) SendIceCandidate(ic *webrtc.ICECandidate) error {
 	c.AppendLog("sending trickle candidate", "candidate", candInit.Candidate)
 	return c.SendRequest(&livekit.SignalRequest{
 		Message: &livekit.SignalRequest_Trickle{
-			Trickle: service.ToProtoTrickle(&candInit),
+			Trickle: rtc.ToProtoTrickle(&candInit),
 		},
 	})
 }
@@ -333,7 +332,7 @@ func (c *RTCClient) Negotiate() error {
 	// send the offer to remote
 	req := &livekit.SignalRequest{
 		Message: &livekit.SignalRequest_Negotiate{
-			Negotiate: service.ToProtoSessionDescription(offer),
+			Negotiate: rtc.ToProtoSessionDescription(offer),
 		},
 	}
 	c.AppendLog("sending negotiate offer to remote...")
@@ -369,7 +368,7 @@ func (c *RTCClient) handleNegotiate(desc webrtc.SessionDescription) error {
 		// send remote an answer
 		return c.SendRequest(&livekit.SignalRequest{
 			Message: &livekit.SignalRequest_Negotiate{
-				Negotiate: service.ToProtoSessionDescription(answer),
+				Negotiate: rtc.ToProtoSessionDescription(answer),
 			},
 		})
 	}
--- a/pkg/rtc/participant.go
+++ b/pkg/rtc/participant.go
@@ -16,7 +16,8 @@ import (

 type Participant struct {
 	id          string
-	conn        *webrtc.PeerConnection
+	peerConn    *webrtc.PeerConnection
+	sigConn     SignalConnection
 	ctx         context.Context
 	cancel      context.CancelFunc
 	mediaEngine *MediaEngine
@@ -35,10 +36,11 @@ type Participant struct {
 	OnOffer func(webrtc.SessionDescription)
 	// OnIceCandidate - ice candidate discovered for local peer
 	OnICECandidate func(c *webrtc.ICECandidateInit)
+	OnStateChange  func(p *Participant, oldState livekit.ParticipantInfo_State)
 	OnClose        func(*Participant)
 }

-func NewParticipant(conf *WebRTCConfig, name string) (*Participant, error) {
+func NewParticipant(conf *WebRTCConfig, sc SignalConnection, name string) (*Participant, error) {
 	me := webrtc.MediaEngine{}
 	me.RegisterDefaultCodecs()
 	api := webrtc.NewAPI(webrtc.WithMediaEngine(me), webrtc.WithSettingEngine(conf.SettingEngine))
@@ -52,7 +54,8 @@ func NewParticipant(conf *WebRTCConfig, name string) (*Participant, error) {
 	participant := &Participant{
 		id:             utils.NewGuid(utils.ParticipantPrefix),
 		name:           name,
-		conn:           pc,
+		peerConn:       pc,
+		sigConn:        sc,
 		ctx:            ctx,
 		cancel:         cancel,
 		state:          livekit.ParticipantInfo_JOINING,
@@ -63,14 +66,30 @@ func NewParticipant(conf *WebRTCConfig, name string) (*Participant, error) {
 	}
 	participant.mediaEngine.RegisterDefaultCodecs()

+	log := logger.GetLogger()
+
 	pc.OnTrack(participant.onTrack)

 	pc.OnICECandidate(func(c *webrtc.ICECandidate) {
 		if c == nil {
 			return
 		}
+		ci := c.ToJSON()
+
+		// write candidate
+		err := sc.WriteResponse(&livekit.SignalResponse{
+			Message: &livekit.SignalResponse_Trickle{
+				Trickle: &livekit.Trickle{
+					Candidate: ci.Candidate,
+					// TODO: there are other candidateInit fields that we might want
+				},
+			},
+		})
+		if err != nil {
+			log.Errorw("could not send trickle", "err", err)
+		}
+
 		if participant.OnICECandidate != nil {
-			ci := c.ToJSON()
 			participant.OnICECandidate(&ci)
 		}
 	})
@@ -78,7 +97,7 @@ func NewParticipant(conf *WebRTCConfig, name string) (*Participant, error) {
 	pc.OnICEConnectionStateChange(func(state webrtc.ICEConnectionState) {
 		logger.GetLogger().Debugw("ICE connection state changed", "state", state.String())
 		if state == webrtc.ICEConnectionStateConnected {
-			participant.state = livekit.ParticipantInfo_ACTIVE
+			participant.updateState(livekit.ParticipantInfo_ACTIVE)
 		}
 	})

@@ -108,58 +127,73 @@ func (p *Participant) ToProto() *livekit.ParticipantInfo {

 // Answer an offer from remote participant
 func (p *Participant) Answer(sdp webrtc.SessionDescription) (answer webrtc.SessionDescription, err error) {
-	// media engine is already set to default codecs upon startup
-	//if err = p.mediaEngine.PopulateFromSDP(sdp); err != nil {
-	//	err = errors.Wrapf(err, "could not parse SDP")
-	//	return
-	//}
-
 	if p.state == livekit.ParticipantInfo_JOINING {
-		p.state = livekit.ParticipantInfo_JOINED
+		p.updateState(livekit.ParticipantInfo_JOINED)
 	}

 	if err = p.SetRemoteDescription(sdp); err != nil {
 		return
 	}

-	answer, err = p.conn.CreateAnswer(nil)
+	answer, err = p.peerConn.CreateAnswer(nil)
 	if err != nil {
 		err = errors.Wrap(err, "could not create answer")
 		return
 	}

-	if err = p.conn.SetLocalDescription(answer); err != nil {
+	if err = p.peerConn.SetLocalDescription(answer); err != nil {
 		err = errors.Wrap(err, "could not set local description")
 		return
 	}

+	// send client the answer
+	err = p.sigConn.WriteResponse(&livekit.SignalResponse{
+		Message: &livekit.SignalResponse_Answer{
+			Answer: ToProtoSessionDescription(answer),
+		},
+	})
+	if err != nil {
+		return
+	}
+
 	// only set after answered
-	p.conn.OnNegotiationNeeded(func() {
+	p.peerConn.OnNegotiationNeeded(func() {
 		logger.GetLogger().Debugw("negotiation needed", "participantId", p.ID())
-		offer, err := p.conn.CreateOffer(nil)
+		offer, err := p.peerConn.CreateOffer(nil)
 		if err != nil {
 			logger.GetLogger().Errorw("could not create offer", "err", err)
 			return
 		}

-		err = p.conn.SetLocalDescription(offer)
+		err = p.peerConn.SetLocalDescription(offer)
 		if err != nil {
 			logger.GetLogger().Errorw("could not set local description", "err", err)
 			return
 		}

 		logger.GetLogger().Debugw("created new offer", "offer", offer, "onOffer", p.OnOffer)
+
+		logger.GetLogger().Debugw("sending available offer to participant")
+		err = p.sigConn.WriteResponse(&livekit.SignalResponse{
+			Message: &livekit.SignalResponse_Negotiate{
+				Negotiate: ToProtoSessionDescription(offer),
+			},
+		})
+		if err != nil {
+			logger.GetLogger().Errorw("could not send offer to peer",
+				"err", err)
+		}
+
 		if p.OnOffer != nil {
 			p.OnOffer(offer)
 		}
 	})
-
 	return
 }

 // SetRemoteDescription when receiving an answer from remote
 func (p *Participant) SetRemoteDescription(sdp webrtc.SessionDescription) error {
-	if err := p.conn.SetRemoteDescription(sdp); err != nil {
+	if err := p.peerConn.SetRemoteDescription(sdp); err != nil {
 		return errors.Wrap(err, "could not set remote description")
 	}
 	return nil
@@ -167,7 +201,7 @@ func (p *Participant) SetRemoteDescription(sdp webrtc.SessionDescription) error

 // AddICECandidate adds candidates for remote peer
 func (p *Participant) AddICECandidate(candidate webrtc.ICECandidateInit) error {
-	if err := p.conn.AddICECandidate(candidate); err != nil {
+	if err := p.peerConn.AddICECandidate(candidate); err != nil {
 		return err
 	}
 	return nil
@@ -183,11 +217,12 @@ func (p *Participant) Close() error {
 	if p.ctx.Err() != nil {
 		return p.ctx.Err()
 	}
+	p.updateState(livekit.ParticipantInfo_DISCONNECTED)
 	if p.OnClose != nil {
 		p.OnClose(p)
 	}
 	p.cancel()
-	return p.conn.Close()
+	return p.peerConn.Close()
 }

 // Subscribes otherPeer to all of the tracks
@@ -216,6 +251,42 @@ func (p *Participant) RemoveSubscriber(peerId string) {
 	}
 }

+// signal connection methods
+func (p *Participant) SendJoinResponse(otherParticipants []*Participant) error {
+	// send Join response
+	return p.sigConn.WriteResponse(&livekit.SignalResponse{
+		Message: &livekit.SignalResponse_Join{
+			Join: &livekit.JoinResponse{
+				Participant:       p.ToProto(),
+				OtherParticipants: ToProtoParticipants(otherParticipants),
+			},
+		},
+	})
+}
+
+func (p *Participant) SendParticipantUpdate(participants []*livekit.ParticipantInfo) error {
+	return p.sigConn.WriteResponse(&livekit.SignalResponse{
+		Message: &livekit.SignalResponse_Update{
+			Update: &livekit.ParticipantUpdate{
+				Participants: participants,
+			},
+		},
+	})
+}
+
+func (p *Participant) updateState(state livekit.ParticipantInfo_State) {
+	if state == p.state {
+		return
+	}
+	oldState := p.state
+	p.state = state
+	if p.OnStateChange != nil {
+		go func() {
+			p.OnStateChange(p, oldState)
+		}()
+	}
+}
+
 // when a new mediaTrack is created, creates a Track and adds it to room
 func (p *Participant) onTrack(track *webrtc.Track, rtpReceiver *webrtc.RTPReceiver) {
 	logger.GetLogger().Debugw("mediaTrack added", "participantId", p.ID(), "mediaTrack", track.Label())
@@ -223,7 +294,7 @@ func (p *Participant) onTrack(track *webrtc.Track, rtpReceiver *webrtc.RTPReceiv
 	// create Receiver
 	// p.mediaEngine.TCCExt
 	receiver := NewReceiver(p.ctx, p.id, rtpReceiver, p.receiverConfig, 0)
-	pt := NewTrack(p.ctx, p.id, p.conn, track, receiver)
+	pt := NewTrack(p.ctx, p.id, p.peerConn, track, receiver)

 	p.lock.Lock()
 	p.tracks = append(p.tracks, pt)
@@ -254,7 +325,7 @@ func (p *Participant) rtcpSendWorker() {
 			}
 			p.lock.RUnlock()
 			if len(pkts) > 0 {
-				if err := p.conn.WriteRTCP(pkts); err != nil {
+				if err := p.peerConn.WriteRTCP(pkts); err != nil {
 					logger.GetLogger().Errorw("error writing RTCP to peer",
 						"peer", p.id,
 						"err", err,
--- a/pkg/rtc/room.go
+++ b/pkg/rtc/room.go
@@ -62,6 +62,10 @@ func (r *Room) Join(participant *Participant) error {

 	participant.OnPeerTrack = r.onTrackAdded

+	participant.OnStateChange = func(p *Participant, oldState livekit.ParticipantInfo_State) {
+		r.broadcastParticipantState(p)
+	}
+
 	logger.GetLogger().Infow("new participant joined",
 		"id", participant.ID(),
 		"name", participant.Name(),
@@ -79,7 +83,15 @@ func (r *Room) Join(participant *Participant) error {

 	r.participants[participant.ID()] = participant

-	return nil
+	// gather other participants and send join response
+	otherParticipants := make([]*Participant, 0, len(r.participants))
+	for _, p := range r.participants {
+		if p.id != participant.id {
+			otherParticipants = append(otherParticipants, p)
+		}
+	}
+
+	return participant.SendJoinResponse(otherParticipants)
 }

 func (r *Room) RemoveParticipant(id string) {
@@ -113,3 +125,23 @@ func (r *Room) onTrackAdded(peer *Participant, track *Track) {
 		}
 	}
 }
+
+func (r *Room) broadcastParticipantState(p *Participant) {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
+
+	updates := ToProtoParticipants([]*Participant{p})
+	for _, op := range r.participants {
+		// skip itself
+		if p.id == op.id {
+			continue
+		}
+
+		err := p.SendParticipantUpdate(updates)
+		if err != nil {
+			logger.GetLogger().Errorw("could not send update to participant",
+				"participant", p.id,
+				"err", err)
+		}
+	}
+}
--- a/pkg/rtc/track.go
+++ b/pkg/rtc/track.go
@@ -62,12 +62,12 @@ func (t *Track) AddSubscriber(participant *Participant) error {
 	packedId := PackTrackId(t.participantId, t.mediaTrack.ID())

 	// use existing SSRC with simple forwarders. adaptive forwarders require unique SSRC per layer
-	outTrack, err := participant.conn.NewTrack(codecs[0].PayloadType, t.mediaTrack.SSRC(), packedId, t.mediaTrack.Label())
+	outTrack, err := participant.peerConn.NewTrack(codecs[0].PayloadType, t.mediaTrack.SSRC(), packedId, t.mediaTrack.Label())
 	if err != nil {
 		return err
 	}

-	rtpSender, err := participant.conn.AddTrack(outTrack)
+	rtpSender, err := participant.peerConn.AddTrack(outTrack)
 	if err != nil {
 		return err
 	}
@@ -78,7 +78,7 @@ func (t *Track) AddSubscriber(participant *Participant) error {
 		delete(t.forwarders, participant.ID())
 		t.lock.Unlock()

-		if err := participant.conn.RemoveTrack(rtpSender); err != nil {
+		if err := participant.peerConn.RemoveTrack(rtpSender); err != nil {
 			logger.GetLogger().Warnw("could not remove mediaTrack from forwarder",
 				"participant", participant.ID(),
 				"err", err)
--- a/pkg/rtc/utils.go
+++ b/pkg/rtc/utils.go
@@ -2,6 +2,10 @@ package rtc

 import (
 	"strings"
+
+	"github.com/pion/webrtc/v3"
+
+	"github.com/livekit/livekit-server/proto/livekit"
 )

 const (
@@ -19,3 +23,48 @@ func UnpackTrackId(packed string) (peerId string, trackId string) {
 func PackTrackId(participantId, trackId string) string {
 	return participantId + trackIdSeparator + trackId
 }
+
+func ToProtoParticipants(participants []*Participant) []*livekit.ParticipantInfo {
+	infos := make([]*livekit.ParticipantInfo, 0, len(participants))
+	for _, op := range participants {
+		infos = append(infos, op.ToProto())
+	}
+	return infos
+}
+
+func ToProtoSessionDescription(sd webrtc.SessionDescription) *livekit.SessionDescription {
+	return &livekit.SessionDescription{
+		Type: sd.Type.String(),
+		Sdp:  sd.SDP,
+	}
+}
+
+func FromProtoSessionDescription(sd *livekit.SessionDescription) webrtc.SessionDescription {
+	var sdType webrtc.SDPType
+	switch sd.Type {
+	case webrtc.SDPTypeOffer.String():
+		sdType = webrtc.SDPTypeOffer
+	case webrtc.SDPTypeAnswer.String():
+		sdType = webrtc.SDPTypeAnswer
+	case webrtc.SDPTypePranswer.String():
+		sdType = webrtc.SDPTypePranswer
+	case webrtc.SDPTypeRollback.String():
+		sdType = webrtc.SDPTypeRollback
+	}
+	return webrtc.SessionDescription{
+		Type: sdType,
+		SDP:  sd.Sdp,
+	}
+}
+
+func ToProtoTrickle(candidateInit *webrtc.ICECandidateInit) *livekit.Trickle {
+	return &livekit.Trickle{
+		Candidate: candidateInit.Candidate,
+	}
+}
+
+func FromProtoTrickle(trickle *livekit.Trickle) *webrtc.ICECandidateInit {
+	return &webrtc.ICECandidateInit{
+		Candidate: trickle.Candidate,
+	}
+}
--- a/pkg/service/wsprotocol.go
+++ b/pkg/service/wsprotocol.go
@@ -1,4 +1,4 @@
-package service
+package rtc

 import (
 	"github.com/gorilla/websocket"
@@ -19,9 +19,10 @@ type WSSignalConnection struct {
 	useJSON bool
 }

-func NewWSSignalConnection(conn *websocket.Conn, name string) *WSSignalConnection {
+func NewWSSignalConnection(conn *websocket.Conn) *WSSignalConnection {
 	return &WSSignalConnection{
-		conn: conn,
+		conn:    conn,
+		useJSON: true,
 	}
 }

--- a/pkg/service/rtc.go
+++ b/pkg/service/rtc.go
@@ -59,11 +59,6 @@ func (s *RTCService) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}

-	participant, err := rtc.NewParticipant(s.manager.Config(), pName)
-	if err != nil {
-		writeJSONError(w, http.StatusInternalServerError, "could not create participant", err.Error())
-	}
-
 	// upgrade only once the basics are good to go
 	conn, err := s.upgrader.Upgrade(w, r, nil)
 	if err != nil {
@@ -75,22 +70,25 @@ func (s *RTCService) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		log.Infow("websocket closed by remote")
 		return nil
 	})
-	defer func() {
-		log.Infow("connection returned")
-	}()
-	signalConn := NewWSSignalConnection(conn, pName)
+	signalConn := rtc.NewWSSignalConnection(conn)

-	// send Join response
-	signalConn.WriteResponse(&livekit.SignalResponse{
-		Message: &livekit.SignalResponse_Join{
-			Join: &livekit.JoinResponse{
-				Participant: participant.ToProto(),
-			},
-		},
-	})
+	participant, err := rtc.NewParticipant(s.manager.Config(), signalConn, pName)
+	if err != nil {
+		writeJSONError(w, http.StatusInternalServerError, "could not create participant", err.Error())
+		return
+	}
+
+	if err := room.Join(participant); err != nil {
+		writeJSONError(w, http.StatusInternalServerError, "could not join room", err.Error())
+		return
+	}
+
+	defer func() {
+		participant.Close()
+		log.Infow("WS connection closed")
+	}()

 	// read connection and wait for commands
-	// TODO: pass in context from WS, so termination of WS would disconnect RTC
 	//ctx := context.Background()
 	for {
 		req, err := signalConn.ReadRequest()
@@ -104,7 +102,7 @@ func (s *RTCService) ServeHTTP(w http.ResponseWriter, r *http.Request) {

 		switch msg := req.Message.(type) {
 		case *livekit.SignalRequest_Offer:
-			err = s.handleJoin(signalConn, room, participant, msg.Offer.Sdp)
+			err = s.handleOffer(participant, msg.Offer)
 			if err != nil {
 				log.Errorw("could not handle join", "err", err, "participant", participant.ID())
 				return
@@ -145,74 +143,22 @@ func (s *RTCService) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }

-func (s *RTCService) handleJoin(sc SignalConnection, room *rtc.Room, participant *rtc.Participant, sdp string) error {
+func (s *RTCService) handleOffer(participant *rtc.Participant, offer *livekit.SessionDescription) error {
 	log := logger.GetLogger()

-	log.Infow("handling join")
-	err := room.Join(participant)
-	if err != nil {
-		return errors.Wrap(err, "could not join room")
-	}
-
-	// TODO: it might be better to return error instead of nil
-	participant.OnICECandidate = func(c *webrtc.ICECandidateInit) {
-		log.Debugw("sending ICE candidate", "participantId", participant.ID())
-		err = sc.WriteResponse(&livekit.SignalResponse{
-			Message: &livekit.SignalResponse_Trickle{
-				Trickle: &livekit.Trickle{
-					Candidate: c.Candidate,
-					// TODO: there are other candidateInit fields that we might want
-				},
-			},
-		})
-		if err != nil {
-			log.Errorw("could not send trickle", "err", err)
-		}
-	}
-
-	// send peer new offer
-	participant.OnOffer = func(o webrtc.SessionDescription) {
-		log.Debugw("sending available offer to participant")
-		err := sc.WriteResponse(&livekit.SignalResponse{
-			Message: &livekit.SignalResponse_Negotiate{
-				Negotiate: ToProtoSessionDescription(o),
-			},
-		})
-		if err != nil {
-			logger.GetLogger().Errorw("could not send offer to peer",
-				"err", err)
-		}
-	}
-
-	offer := webrtc.SessionDescription{
-		Type: webrtc.SDPTypeOffer,
-		SDP:  sdp,
-	}
-	answer, err := participant.Answer(offer)
+	_, err := participant.Answer(rtc.FromProtoSessionDescription(offer))
 	if err != nil {
 		return errors.Wrap(err, "could not answer offer")
 	}

-	logger.GetLogger().Debugw("answered, writing response")
-
-	// finally send answer
-	err = sc.WriteResponse(&livekit.SignalResponse{
-		Message: &livekit.SignalResponse_Answer{
-			Answer: ToProtoSessionDescription(answer),
-		},
-	})
-
-	if err != nil {
-		return errors.Wrap(err, "could not create answer")
-	}
-
+	log.Debugw("answered client offer")
 	return nil
 }

-func (s *RTCService) handleNegotiate(sc SignalConnection, peer *rtc.Participant, neg *livekit.SessionDescription) error {
+func (s *RTCService) handleNegotiate(sc rtc.SignalConnection, peer *rtc.Participant, neg *livekit.SessionDescription) error {
 	logger.GetLogger().Debugw("handling incoming negotiate")
 	if neg.Type == webrtc.SDPTypeOffer.String() {
-		offer := FromProtoSessionDescription(neg)
+		offer := rtc.FromProtoSessionDescription(neg)
 		answer, err := peer.Answer(offer)
 		if err != nil {
 			return err
@@ -220,7 +166,7 @@ func (s *RTCService) handleNegotiate(sc SignalConnection, peer *rtc.Participant,

 		err = sc.WriteResponse(&livekit.SignalResponse{
 			Message: &livekit.SignalResponse_Negotiate{
-				Negotiate: ToProtoSessionDescription(answer),
+				Negotiate: rtc.ToProtoSessionDescription(answer),
 			},
 		})

@@ -228,7 +174,7 @@ func (s *RTCService) handleNegotiate(sc SignalConnection, peer *rtc.Participant,
 			return err
 		}
 	} else if neg.Type == webrtc.SDPTypeAnswer.String() {
-		answer := FromProtoSessionDescription(neg)
+		answer := rtc.FromProtoSessionDescription(neg)
 		err := peer.SetRemoteDescription(answer)
 		if err != nil {
 			return err
@@ -238,7 +184,7 @@ func (s *RTCService) handleNegotiate(sc SignalConnection, peer *rtc.Participant,
 }

 func (s *RTCService) handleTrickle(peer *rtc.Participant, trickle *livekit.Trickle) error {
-	candidateInit := FromProtoTrickle(trickle)
+	candidateInit := rtc.FromProtoTrickle(trickle)
 	logger.GetLogger().Debugw("adding peer candidate", "participantId", peer.ID())
 	if err := peer.AddICECandidate(*candidateInit); err != nil {
 		return err
--- a/pkg/service/utils.go
+++ b/pkg/service/utils.go
@@ -1,44 +0,0 @@
-package service
-
-import (
-	"github.com/pion/webrtc/v3"
-
-	"github.com/livekit/livekit-server/proto/livekit"
-)
-
-func ToProtoSessionDescription(sd webrtc.SessionDescription) *livekit.SessionDescription {
-	return &livekit.SessionDescription{
-		Type: sd.Type.String(),
-		Sdp:  sd.SDP,
-	}
-}
-
-func FromProtoSessionDescription(sd *livekit.SessionDescription) webrtc.SessionDescription {
-	var sdType webrtc.SDPType
-	switch sd.Type {
-	case webrtc.SDPTypeOffer.String():
-		sdType = webrtc.SDPTypeOffer
-	case webrtc.SDPTypeAnswer.String():
-		sdType = webrtc.SDPTypeAnswer
-	case webrtc.SDPTypePranswer.String():
-		sdType = webrtc.SDPTypePranswer
-	case webrtc.SDPTypeRollback.String():
-		sdType = webrtc.SDPTypeRollback
-	}
-	return webrtc.SessionDescription{
-		Type: sdType,
-		SDP:  sd.Sdp,
-	}
-}
-
-func ToProtoTrickle(candidateInit *webrtc.ICECandidateInit) *livekit.Trickle {
-	return &livekit.Trickle{
-		Candidate: candidateInit.Candidate,
-	}
-}
-
-func FromProtoTrickle(trickle *livekit.Trickle) *webrtc.ICECandidateInit {
-	return &webrtc.ICECandidateInit{
-		Candidate: trickle.Candidate,
-	}
-}
--- a/proto/livekit/model.pb.go
+++ b/proto/livekit/model.pb.go
@@ -81,6 +81,55 @@ func (ParticipantInfo_State) EnumDescriptor() ([]byte, []int) {
 	return file_model_proto_rawDescGZIP(), []int{4, 0}
 }

+type TrackInfo_Type int32
+
+const (
+	TrackInfo_AUDIO TrackInfo_Type = 0
+	TrackInfo_VIDEO TrackInfo_Type = 1
+	TrackInfo_DATA  TrackInfo_Type = 2
+)
+
+// Enum value maps for TrackInfo_Type.
+var (
+	TrackInfo_Type_name = map[int32]string{
+		0: "AUDIO",
+		1: "VIDEO",
+		2: "DATA",
+	}
+	TrackInfo_Type_value = map[string]int32{
+		"AUDIO": 0,
+		"VIDEO": 1,
+		"DATA":  2,
+	}
+)
+
+func (x TrackInfo_Type) Enum() *TrackInfo_Type {
+	p := new(TrackInfo_Type)
+	*p = x
+	return p
+}
+
+func (x TrackInfo_Type) String() string {
+	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
+}
+
+func (TrackInfo_Type) Descriptor() protoreflect.EnumDescriptor {
+	return file_model_proto_enumTypes[1].Descriptor()
+}
+
+func (TrackInfo_Type) Type() protoreflect.EnumType {
+	return &file_model_proto_enumTypes[1]
+}
+
+func (x TrackInfo_Type) Number() protoreflect.EnumNumber {
+	return protoreflect.EnumNumber(x)
+}
+
+// Deprecated: Use TrackInfo_Type.Descriptor instead.
+func (TrackInfo_Type) EnumDescriptor() ([]byte, []int) {
+	return file_model_proto_rawDescGZIP(), []int{5, 0}
+}
+
 type Node struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -363,11 +412,9 @@ type ParticipantInfo struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields

-	Id       string                `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
-	Name     string                `protobuf:"bytes,2,opt,name=name,proto3" json:"name,omitempty"`
-	State    ParticipantInfo_State `protobuf:"varint,3,opt,name=state,proto3,enum=livekit.ParticipantInfo_State" json:"state,omitempty"`
-	HasAudio bool                  `protobuf:"varint,4,opt,name=has_audio,json=hasAudio,proto3" json:"has_audio,omitempty"`
-	HasVideo bool                  `protobuf:"varint,5,opt,name=has_video,json=hasVideo,proto3" json:"has_video,omitempty"`
+	Id    string                `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
+	Name  string                `protobuf:"bytes,2,opt,name=name,proto3" json:"name,omitempty"`
+	State ParticipantInfo_State `protobuf:"varint,3,opt,name=state,proto3,enum=livekit.ParticipantInfo_State" json:"state,omitempty"`
 }

 func (x *ParticipantInfo) Reset() {
@@ -423,18 +470,68 @@ func (x *ParticipantInfo) GetState() ParticipantInfo_State {
 	return ParticipantInfo_JOINING
 }

-func (x *ParticipantInfo) GetHasAudio() bool {
-	if x != nil {
-		return x.HasAudio
-	}
-	return false
+// describing
+type TrackInfo struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Id   string         `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
+	Type TrackInfo_Type `protobuf:"varint,2,opt,name=type,proto3,enum=livekit.TrackInfo_Type" json:"type,omitempty"`
+	Name string         `protobuf:"bytes,3,opt,name=name,proto3" json:"name,omitempty"`
 }

-func (x *ParticipantInfo) GetHasVideo() bool {
-	if x != nil {
-		return x.HasVideo
+func (x *TrackInfo) Reset() {
+	*x = TrackInfo{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_model_proto_msgTypes[5]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
 	}
-	return false
+}
+
+func (x *TrackInfo) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*TrackInfo) ProtoMessage() {}
+
+func (x *TrackInfo) ProtoReflect() protoreflect.Message {
+	mi := &file_model_proto_msgTypes[5]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use TrackInfo.ProtoReflect.Descriptor instead.
+func (*TrackInfo) Descriptor() ([]byte, []int) {
+	return file_model_proto_rawDescGZIP(), []int{5}
+}
+
+func (x *TrackInfo) GetId() string {
+	if x != nil {
+		return x.Id
+	}
+	return ""
+}
+
+func (x *TrackInfo) GetType() TrackInfo_Type {
+	if x != nil {
+		return x.Type
+	}
+	return TrackInfo_AUDIO
+}
+
+func (x *TrackInfo) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
 }

 type DataChannel struct {
@@ -449,7 +546,7 @@ type DataChannel struct {
 func (x *DataChannel) Reset() {
 	*x = DataChannel{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_model_proto_msgTypes[5]
+		mi := &file_model_proto_msgTypes[6]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -462,7 +559,7 @@ func (x *DataChannel) String() string {
 func (*DataChannel) ProtoMessage() {}

 func (x *DataChannel) ProtoReflect() protoreflect.Message {
-	mi := &file_model_proto_msgTypes[5]
+	mi := &file_model_proto_msgTypes[6]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -475,7 +572,7 @@ func (x *DataChannel) ProtoReflect() protoreflect.Message {

 // Deprecated: Use DataChannel.ProtoReflect.Descriptor instead.
 func (*DataChannel) Descriptor() ([]byte, []int) {
-	return file_model_proto_rawDescGZIP(), []int{5}
+	return file_model_proto_rawDescGZIP(), []int{6}
 }

 func (x *DataChannel) GetSessionId() string {
@@ -525,29 +622,34 @@ var file_model_proto_rawDesc = []byte{
 	0x69, 0x6f, 0x6e, 0x5f, 0x74, 0x69, 0x6d, 0x65, 0x18, 0x03, 0x20, 0x01, 0x28, 0x03, 0x52, 0x0c,
 	0x63, 0x72, 0x65, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x54, 0x69, 0x6d, 0x65, 0x12, 0x14, 0x0a, 0x05,
 	0x74, 0x6f, 0x6b, 0x65, 0x6e, 0x18, 0x04, 0x20, 0x01, 0x28, 0x09, 0x52, 0x05, 0x74, 0x6f, 0x6b,
-	0x65, 0x6e, 0x22, 0xe5, 0x01, 0x0a, 0x0f, 0x50, 0x61, 0x72, 0x74, 0x69, 0x63, 0x69, 0x70, 0x61,
+	0x65, 0x6e, 0x22, 0xab, 0x01, 0x0a, 0x0f, 0x50, 0x61, 0x72, 0x74, 0x69, 0x63, 0x69, 0x70, 0x61,
 	0x6e, 0x74, 0x49, 0x6e, 0x66, 0x6f, 0x12, 0x0e, 0x0a, 0x02, 0x69, 0x64, 0x18, 0x01, 0x20, 0x01,
 	0x28, 0x09, 0x52, 0x02, 0x69, 0x64, 0x12, 0x12, 0x0a, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x18, 0x02,
 	0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x12, 0x34, 0x0a, 0x05, 0x73, 0x74,
 	0x61, 0x74, 0x65, 0x18, 0x03, 0x20, 0x01, 0x28, 0x0e, 0x32, 0x1e, 0x2e, 0x6c, 0x69, 0x76, 0x65,
 	0x6b, 0x69, 0x74, 0x2e, 0x50, 0x61, 0x72, 0x74, 0x69, 0x63, 0x69, 0x70, 0x61, 0x6e, 0x74, 0x49,
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-	0x6f, 0x61, 0x64, 0x18, 0x02, 0x20, 0x01, 0x28, 0x0c, 0x52, 0x07, 0x70, 0x61, 0x79, 0x6c, 0x6f,
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-	0x76, 0x65, 0x6b, 0x69, 0x74, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
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+	0x4e, 0x49, 0x4e, 0x47, 0x10, 0x00, 0x12, 0x0a, 0x0a, 0x06, 0x4a, 0x4f, 0x49, 0x4e, 0x45, 0x44,
+	0x10, 0x01, 0x12, 0x0a, 0x0a, 0x06, 0x41, 0x43, 0x54, 0x49, 0x56, 0x45, 0x10, 0x02, 0x12, 0x10,
+	0x0a, 0x0c, 0x44, 0x49, 0x53, 0x43, 0x4f, 0x4e, 0x4e, 0x45, 0x43, 0x54, 0x45, 0x44, 0x10, 0x03,
+	0x22, 0x84, 0x01, 0x0a, 0x09, 0x54, 0x72, 0x61, 0x63, 0x6b, 0x49, 0x6e, 0x66, 0x6f, 0x12, 0x0e,
+	0x0a, 0x02, 0x69, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x02, 0x69, 0x64, 0x12, 0x2b,
+	0x0a, 0x04, 0x74, 0x79, 0x70, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x0e, 0x32, 0x17, 0x2e, 0x6c,
+	0x69, 0x76, 0x65, 0x6b, 0x69, 0x74, 0x2e, 0x54, 0x72, 0x61, 0x63, 0x6b, 0x49, 0x6e, 0x66, 0x6f,
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+	0x61, 0x6d, 0x65, 0x18, 0x03, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x22,
+	0x26, 0x0a, 0x04, 0x54, 0x79, 0x70, 0x65, 0x12, 0x09, 0x0a, 0x05, 0x41, 0x55, 0x44, 0x49, 0x4f,
+	0x10, 0x00, 0x12, 0x09, 0x0a, 0x05, 0x56, 0x49, 0x44, 0x45, 0x4f, 0x10, 0x01, 0x12, 0x08, 0x0a,
+	0x04, 0x44, 0x41, 0x54, 0x41, 0x10, 0x02, 0x22, 0x46, 0x0a, 0x0b, 0x44, 0x61, 0x74, 0x61, 0x43,
+	0x68, 0x61, 0x6e, 0x6e, 0x65, 0x6c, 0x12, 0x1d, 0x0a, 0x0a, 0x73, 0x65, 0x73, 0x73, 0x69, 0x6f,
+	0x6e, 0x5f, 0x69, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x09, 0x73, 0x65, 0x73, 0x73,
+	0x69, 0x6f, 0x6e, 0x49, 0x64, 0x12, 0x18, 0x0a, 0x07, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+	0x18, 0x02, 0x20, 0x01, 0x28, 0x0c, 0x52, 0x07, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64, 0x42,
+	0x31, 0x5a, 0x2f, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x6c, 0x69,
+	0x76, 0x65, 0x6b, 0x69, 0x74, 0x2f, 0x6c, 0x69, 0x76, 0x65, 0x6b, 0x69, 0x74, 0x2d, 0x73, 0x65,
+	0x72, 0x76, 0x65, 0x72, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2f, 0x6c, 0x69, 0x76, 0x65, 0x6b,
+	0x69, 0x74, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }

 var (
@@ -562,25 +664,28 @@ func file_model_proto_rawDescGZIP() []byte {
 	return file_model_proto_rawDescData
 }

-var file_model_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_model_proto_msgTypes = make([]protoimpl.MessageInfo, 6)
+var file_model_proto_enumTypes = make([]protoimpl.EnumInfo, 2)
+var file_model_proto_msgTypes = make([]protoimpl.MessageInfo, 7)
 var file_model_proto_goTypes = []interface{}{
 	(ParticipantInfo_State)(0), // 0: livekit.ParticipantInfo.State
-	(*Node)(nil),               // 1: livekit.Node
-	(*NodeStats)(nil),          // 2: livekit.NodeStats
-	(*Room)(nil),               // 3: livekit.Room
-	(*RoomInfo)(nil),           // 4: livekit.RoomInfo
-	(*ParticipantInfo)(nil),    // 5: livekit.ParticipantInfo
-	(*DataChannel)(nil),        // 6: livekit.DataChannel
+	(TrackInfo_Type)(0),        // 1: livekit.TrackInfo.Type
+	(*Node)(nil),               // 2: livekit.Node
+	(*NodeStats)(nil),          // 3: livekit.NodeStats
+	(*Room)(nil),               // 4: livekit.Room
+	(*RoomInfo)(nil),           // 5: livekit.RoomInfo
+	(*ParticipantInfo)(nil),    // 6: livekit.ParticipantInfo
+	(*TrackInfo)(nil),          // 7: livekit.TrackInfo
+	(*DataChannel)(nil),        // 8: livekit.DataChannel
 }
 var file_model_proto_depIdxs = []int32{
-	2, // 0: livekit.Node.stats:type_name -> livekit.NodeStats
+	3, // 0: livekit.Node.stats:type_name -> livekit.NodeStats
 	0, // 1: livekit.ParticipantInfo.state:type_name -> livekit.ParticipantInfo.State
-	2, // [2:2] is the sub-list for method output_type
-	2, // [2:2] is the sub-list for method input_type
-	2, // [2:2] is the sub-list for extension type_name
-	2, // [2:2] is the sub-list for extension extendee
-	0, // [0:2] is the sub-list for field type_name
+	1, // 2: livekit.TrackInfo.type:type_name -> livekit.TrackInfo.Type
+	3, // [3:3] is the sub-list for method output_type
+	3, // [3:3] is the sub-list for method input_type
+	3, // [3:3] is the sub-list for extension type_name
+	3, // [3:3] is the sub-list for extension extendee
+	0, // [0:3] is the sub-list for field type_name
 }

 func init() { file_model_proto_init() }
@@ -650,6 +755,18 @@ func file_model_proto_init() {
 			}
 		}
 		file_model_proto_msgTypes[5].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*TrackInfo); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_model_proto_msgTypes[6].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*DataChannel); i {
 			case 0:
 				return &v.state
@@ -667,8 +784,8 @@ func file_model_proto_init() {
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_model_proto_rawDesc,
-			NumEnums:      1,
-			NumMessages:   6,
+			NumEnums:      2,
+			NumMessages:   7,
 			NumExtensions: 0,
 			NumServices:   0,
 		},
--- a/proto/livekit/rtc.pb.go
+++ b/proto/livekit/rtc.pb.go
@@ -143,6 +143,7 @@ type SignalResponse struct {
 	//	*SignalResponse_Answer
 	//	*SignalResponse_Negotiate
 	//	*SignalResponse_Trickle
+	//	*SignalResponse_Update
 	Message isSignalResponse_Message `protobuf_oneof:"message"`
 }

@@ -213,6 +214,13 @@ func (x *SignalResponse) GetTrickle() *Trickle {
 	return nil
 }

+func (x *SignalResponse) GetUpdate() *ParticipantUpdate {
+	if x, ok := x.GetMessage().(*SignalResponse_Update); ok {
+		return x.Update
+	}
+	return nil
+}
+
 type isSignalResponse_Message interface {
 	isSignalResponse_Message()
 }
@@ -237,6 +245,11 @@ type SignalResponse_Trickle struct {
 	Trickle *Trickle `protobuf:"bytes,4,opt,name=trickle,proto3,oneof"`
 }

+type SignalResponse_Update struct {
+	// sent when participants in the room has changed
+	Update *ParticipantUpdate `protobuf:"bytes,5,opt,name=update,proto3,oneof"`
+}
+
 func (*SignalResponse_Join) isSignalResponse_Message() {}

 func (*SignalResponse_Answer) isSignalResponse_Message() {}
@@ -245,6 +258,8 @@ func (*SignalResponse_Negotiate) isSignalResponse_Message() {}

 func (*SignalResponse_Trickle) isSignalResponse_Message() {}

+func (*SignalResponse_Update) isSignalResponse_Message() {}
+
 type Trickle struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -352,7 +367,8 @@ type JoinResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields

-	Participant *ParticipantInfo `protobuf:"bytes,1,opt,name=participant,proto3" json:"participant,omitempty"`
+	Participant       *ParticipantInfo   `protobuf:"bytes,1,opt,name=participant,proto3" json:"participant,omitempty"`
+	OtherParticipants []*ParticipantInfo `protobuf:"bytes,2,rep,name=other_participants,json=otherParticipants,proto3" json:"other_participants,omitempty"`
 }

 func (x *JoinResponse) Reset() {
@@ -394,6 +410,13 @@ func (x *JoinResponse) GetParticipant() *ParticipantInfo {
 	return nil
 }

+func (x *JoinResponse) GetOtherParticipants() []*ParticipantInfo {
+	if x != nil {
+		return x.OtherParticipants
+	}
+	return nil
+}
+
 type MediaControl struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -436,6 +459,8 @@ type ParticipantUpdate struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
+
+	Participants []*ParticipantInfo `protobuf:"bytes,1,rep,name=participants,proto3" json:"participants,omitempty"`
 }

 func (x *ParticipantUpdate) Reset() {
@@ -470,6 +495,13 @@ func (*ParticipantUpdate) Descriptor() ([]byte, []int) {
 	return file_rtc_proto_rawDescGZIP(), []int{6}
 }

+func (x *ParticipantUpdate) GetParticipants() []*ParticipantInfo {
+	if x != nil {
+		return x.Participants
+	}
+	return nil
+}
+
 var File_rtc_proto protoreflect.FileDescriptor

 var file_rtc_proto_rawDesc = []byte{
@@ -490,7 +522,7 @@ var file_rtc_proto_rawDesc = []byte{
 	0x20, 0x01, 0x28, 0x0b, 0x32, 0x15, 0x2e, 0x6c, 0x69, 0x76, 0x65, 0x6b, 0x69, 0x74, 0x2e, 0x4d,
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 	0x6f, 0x6e, 0x73, 0x65, 0x12, 0x2b, 0x0a, 0x04, 0x6a, 0x6f, 0x69, 0x6e, 0x18, 0x01, 0x20, 0x01,
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@@ -504,24 +536,36 @@ var file_rtc_proto_rawDesc = []byte{
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 }

 var (
@@ -548,20 +592,23 @@ var file_rtc_proto_goTypes = []interface{}{
 	(*ParticipantInfo)(nil),    // 7: livekit.ParticipantInfo
 }
 var file_rtc_proto_depIdxs = []int32{
-	3, // 0: livekit.SignalRequest.offer:type_name -> livekit.SessionDescription
-	3, // 1: livekit.SignalRequest.negotiate:type_name -> livekit.SessionDescription
-	2, // 2: livekit.SignalRequest.trickle:type_name -> livekit.Trickle
-	5, // 3: livekit.SignalRequest.control:type_name -> livekit.MediaControl
-	4, // 4: livekit.SignalResponse.join:type_name -> livekit.JoinResponse
-	3, // 5: livekit.SignalResponse.answer:type_name -> livekit.SessionDescription
-	3, // 6: livekit.SignalResponse.negotiate:type_name -> livekit.SessionDescription
-	2, // 7: livekit.SignalResponse.trickle:type_name -> livekit.Trickle
-	7, // 8: livekit.JoinResponse.participant:type_name -> livekit.ParticipantInfo
-	9, // [9:9] is the sub-list for method output_type
-	9, // [9:9] is the sub-list for method input_type
-	9, // [9:9] is the sub-list for extension type_name
-	9, // [9:9] is the sub-list for extension extendee
-	0, // [0:9] is the sub-list for field type_name
+	3,  // 0: livekit.SignalRequest.offer:type_name -> livekit.SessionDescription
+	3,  // 1: livekit.SignalRequest.negotiate:type_name -> livekit.SessionDescription
+	2,  // 2: livekit.SignalRequest.trickle:type_name -> livekit.Trickle
+	5,  // 3: livekit.SignalRequest.control:type_name -> livekit.MediaControl
+	4,  // 4: livekit.SignalResponse.join:type_name -> livekit.JoinResponse
+	3,  // 5: livekit.SignalResponse.answer:type_name -> livekit.SessionDescription
+	3,  // 6: livekit.SignalResponse.negotiate:type_name -> livekit.SessionDescription
+	2,  // 7: livekit.SignalResponse.trickle:type_name -> livekit.Trickle
+	6,  // 8: livekit.SignalResponse.update:type_name -> livekit.ParticipantUpdate
+	7,  // 9: livekit.JoinResponse.participant:type_name -> livekit.ParticipantInfo
+	7,  // 10: livekit.JoinResponse.other_participants:type_name -> livekit.ParticipantInfo
+	7,  // 11: livekit.ParticipantUpdate.participants:type_name -> livekit.ParticipantInfo
+	12, // [12:12] is the sub-list for method output_type
+	12, // [12:12] is the sub-list for method input_type
+	12, // [12:12] is the sub-list for extension type_name
+	12, // [12:12] is the sub-list for extension extendee
+	0,  // [0:12] is the sub-list for field type_name
 }

 func init() { file_rtc_proto_init() }
@@ -667,6 +714,7 @@ func file_rtc_proto_init() {
 		(*SignalResponse_Answer)(nil),
 		(*SignalResponse_Negotiate)(nil),
 		(*SignalResponse_Trickle)(nil),
+		(*SignalResponse_Update)(nil),
 	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
--- a/proto/model.proto
+++ b/proto/model.proto
@@ -45,10 +45,21 @@ message ParticipantInfo {
  string id = 1;
  string name = 2;
  State state = 3;
-  bool has_audio = 4;
-  bool has_video = 5;
 }

+// describing
+message TrackInfo {
+  enum Type {
+    AUDIO = 0;
+    VIDEO = 1;
+    DATA = 2;
+  }
+  string id = 1;
+  Type type = 2;
+  string name = 3;
+}
+
+
 message DataChannel {
  string session_id = 1;
  bytes payload = 2;
--- a/proto/rtc.proto
+++ b/proto/rtc.proto
@@ -24,7 +24,8 @@ message SignalResponse {
    SessionDescription negotiate = 3;
    // sent when an ICE candidate is available
    Trickle trickle = 4;
-
+    // sent when participants in the room has changed
+    ParticipantUpdate update = 5;
  }
 }

@@ -39,6 +40,7 @@ message SessionDescription {

 message JoinResponse {
  ParticipantInfo participant = 1;
+  repeated ParticipantInfo other_participants = 2;
 }

 message MediaControl {
@@ -46,5 +48,5 @@ message MediaControl {
 }

 message ParticipantUpdate {
-
+  repeated ParticipantInfo participants = 1;
 }