I add below code , but no change
//add listeners
f.addListener(WCSEvent.ErrorStatusEvent, errorEvent);
f.addListener(WCSEvent.ConnectionStatusEvent, connectionStatusListener);
f.addListener(WCSEvent.StreamStatusEvent, streamStatusListener);
var configuration = new Configuration();
configuration.wsPlayerCanvas = document.getElementById('videoCanvas');
contents=configuration.wsPlayerCanvas.getContext("2d"); // add by my
contents.rotate(30*Math.PI/180); // add by my
configuration.wsPlayerReceiverPath = "WSReceiver.js";
configuration.videoWidth = 320;
configuration.videoHeight = 240;
in vow-player.js