Overview and Requirements

Video Streaming Note

In building this project I found network video cameras, such as those used for security and monitoring, work best for streaming video. I attempted to use a webcam that streamed video to sites such as Ustream or Livestream, but found the latency of those streams was extremely high--on the order of 10-15 seconds. With such high latency it is not possible to control the laser through the web in real time. I even tested setting up my own video streaming server with Amazon EC2 CloudFront, but still could not get a low enough latency video stream.

In addition to high latency, I also found embedded video streams (such as from video streaming web services) are not easily adapted for the control needs of this project. The problem is that web browsers enforce a strict cross-domain security model which does not allow a video embedded in an iframe or object (the typical means for embedding web video) to expose click and other events to the parent web page. This means targeting the laser with clicks on the video is not possible (at best you could present a 'track pad' target area below the video, or a joystick/direction pad control for manual movement--neither is as ideal as targeting directly from the video).

Using a network video camera that outputs an MJPEG video stream solves both these problems by having low latency encoding (at the expense of higher bandwidth compared to more modern video codecs), and the ability to embed directly in an image tag which is not subject to as strict cross-domain security restrictions.