webrtc: fix support for video + audio

internal/core/webrtc_conn.go

@@ -349,9 +349,10 @@ outer:
 	writeError := make(chan error)
 
 	for _, track := range tracks {
+		ctrack := track
 		res.stream.readerAdd(c, track.media, track.format, func(dat data) {
 			ringBuffer.Push(func() {
-				track.cb(dat, ctx, writeError)
+				ctrack.cb(dat, ctx, writeError)
 			})
 		})
 	}

internal/core/webrtc_index.html

@@ -93,7 +93,7 @@ class Receiver {
 
         this.pc.ontrack = (evt) => {
             console.log("new track " + evt.track.kind);
-            document.getElementById("video").srcObject = new MediaStream([evt.track]);
+            document.getElementById("video").srcObject = evt.streams[0];
         };
 
         const direction = "sendrecv";