replace video track on demand.

internal/types/event/events.go

@@ -11,6 +11,7 @@ const (
 	SIGNAL_ANSWER    = "signal/answer"
 	SIGNAL_PROVIDE   = "signal/provide"
 	SIGNAL_CANDIDATE = "signal/candidate"
+	SIGNAL_VIDEO     = "signal/video"
 )
 
 const (

internal/types/message/messages.go

@@ -57,6 +57,11 @@ type SignalAnswer struct {
 	SDP   string `json:"sdp"`
 }
 
+type SignalVideo struct {
+	Event   string `json:"event,omitempty"`
+	VideoID string `json:"video_id"`
+}
+
 /////////////////////////////
 // Member
 /////////////////////////////