Video and audio: playing media in the browser - HTML5 in Action - page 367

You will also need a Grayed button inside the menu and a handler in the switch statement.
This will work analogously to the Framed button you created in listing 8.13 , so we won't
repeat the code here.
Code check!
The file index-6.html in the topic's code download is a working version of the code to this
point (but see section 8.3.1 if you're using IE9).
Note
Image processing works pixel by pixel, which means it becomes increasingly more expens-
ive the higher the quality of the video. Unless you're building an application to preview
video processing results, your users will usually be grateful if you do expensive real-time
processing on the server, instead of in their browser.
8.4.4. Building the telestrator features
Using the techniques from the previous section of rendering the video through a <can-
vas> element and overlaying graphics on that video, you can now add the telestration
feature. The results, demonstrating the artistic abilities of the authors, are shown in figure
8.10 .