如何在Windows.Forms.PictureBox中正确显示Kinect视频流？

I'm trying to display Kinect's video stream into PictureBox. The reason is, I'd like to overlay it with some images and use FillEllipse() method to add real time markers. However, I ended up with a box with a red x (cross) in it. Could someone show me, where did I go wrong? Should I use WritableBitmap instead? I had a thought of this, but Writeable bitmap does not offer method such as FillEllipse() to place markers.I'm trying to display Kinect's video stream int