diff --git a/cmd/mjpeg/mjpeg.go b/cmd/mjpeg/mjpeg.go
index 5c16999e..fe68e17d 100644
--- a/cmd/mjpeg/mjpeg.go
+++ b/cmd/mjpeg/mjpeg.go
@@ -121,6 +121,8 @@ func handlerWS(tr *api.Transport, _ *api.Message) error {
 		return err
 	}
 
+	tr.Write(&api.Message{Type: "mjpeg"})
+
 	tr.OnClose(func() {
 		stream.RemoveConsumer(cons)
 	})
diff --git a/cmd/mp4/ws.go b/cmd/mp4/ws.go
index 64faa6ee..0aba83c3 100644
--- a/cmd/mp4/ws.go
+++ b/cmd/mp4/ws.go
@@ -86,6 +86,8 @@ func handlerWSMP4(tr *api.Transport, msg *api.Message) error {
 		return err
 	}
 
+	tr.Write(&api.Message{Type: "mp4", Value: cons.MimeType})
+
 	tr.OnClose(func() {
 		stream.RemoveConsumer(cons)
 	})