Is there a webcam that I can use as a document camera. A document camera is a camera placed above a book or other document and the video is shown on a computer screen. For this application, I need to have little video lag as I want to draw figures with a pen on the book or paper pad. Most webcams claim HD resolution at 30 frames per second but none of them so far can deliver. Any help out there?
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No, because I don’t expect brilliant (or even decent) output from a webcam.
The only webcam I have is the 720p integrated camera on my laptop, and even it reduces shutter speed to the point that most video looks as though it’s being captured at ~15fps. It does well enough in lots of sunlight though.
“If you look at the uncompressed data rate of the video, it is 1.5 gbits/sec much higher than USB 2 can support.”
Well, you’d need DVI or HDMI to transfer uncompressed 1080p video. That’s why all USB video devices either (a) make use of an integrated video encoder, or (b) stream video that has been pre-compressed (a USB blu-ray drive works this way).
The video encoder is a fixed-function DSP–it’ll have no problem outputting a 10-30mbps 1080p h.264 video stream. If the computer on the other end is less than 8 years old, it should have no problem decoding that stream. However, the optics in webcams are quite poor and usually have trouble capturing HD video in less than stellar lighting conditions. To compensate, they cut shutter speed in half (sometimes even more) in order to make the output video a little easier to see. That reduced shutter speed is what makes the video choppy.
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