I am working on drawing app for windows phone 8.I want to capture video while I am drawing in screen is it possible? please give me any idea if u have, Actually it's possible in iOS I had worked on that but I was searching a lot in internet there is no help please let me give any idea how it will be possible. Thanks
You could also use Expression Encoder 4 (http://www.microsoft.com/en-us/download/confirmation.aspx?id=27870) to screen capture the WP8 emulator and get a nice video out of it. You can define the screen area, clipping the emulator shell if you want.
Here is a couple of posts on how to do it: http://blogs.msdn.com/b/mikeormond/archive/2010/09/27/windows-phone-7-screen-capture.aspx http://richarddunbar.blogspot.co.uk/2013/01/a-cool-way-to-promote-your-app.html
Sadly nothing was released yet (at least nothing official). Some stores offer a HDMI cable for Nokia Lumia 920, but as I heard, it is a scam. Some developers succeeded in this with a jailbroken device, but that is not really a good solution. Finally - you can certainly use the emulator and record the Window using some kind of screen capturing software, but that will sadly cause performance issues (the emulator causes some lagging of apps). That means either that, or wait until Microsoft solves this somehow...
来源：https://stackoverflow.com/questions/14873226/capture-a-video-for-screen-activity-in-windows-phone-8