Video Hooking

I want to write an app that hooks the changes in the video, so they can be played back like a movie of the screen activity.  Can anyone help me get started?  I am looking for working examples of this.
perksterAsked:
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mdouganCommented:
When you say "changes in the video" are you taking about changes to the "desktop", meaning anychanges that appear on the screen?

If so, then there are pieces of code that I could give you that you might be able to pull together to get it to work, but I don't know how satisfying it will be for you.

The basic approach would be to get the window handle of the desktop window (I think if you use GetWindow(0) or some API call like that you can get the window handle of the desktop.  Once you have that, you can hook the window proc of that window.

The window proc will be called whenever the window needs to repaint (which for the desktop is probably very often).  You can look for this message, and then do something each time the message arrives.  Namely, you can get the hDC of the desktop window, and then bitblt it to a picturebox, then save the picture out to a bmp file.

However, it will take some time to output each bmp, and if you are getting a lot of paint events, then you run the risk of bogging down the desktop refreshes.

Ideally, you'd be able to send each screen capture to a frame in an AVI or MPEG video, but you'd probably need a special control for this.  I'm not sure how it would work.

Saving all of these bmps will take up a huge amount of disk space (even if you convert the pictures to jpg before saving them).  So, it's not clear how practical your request is.
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perksterAuthor Commented:
I appreciate the good info.
What I am looking for is to create an application similar to Lotus ScreenCam, etc.  where you can record the activity on your screen like a movie.
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DanRollinsCommented:
Hi perkster,
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