Hot answers tagged capturing
You can do this with Processing. You would have to write a processing sketch to step through the movie frame-by-frame, and calculate how different each was from the previous frame. When the difference is above a certain threshold, save the whole frame as an image file. Here is a forum post about something very similar. Other than processing, you may ...
1 - No, you will need more than one card. 2 - It's entirely dependant on your motherboard, but where i work we have 2 Black Magic Intensity Pro cards, and they do an excellent job of capturing HD footage over HDMI. They are also relatively cheap, so would suit your needs. They also allow you to run multiple cards in a single system.
The cheapest boards i know: the elgato game capture HD. the BMD Intensity series. In that price-category you will need one board per camera. You don't need additional HDMI- or FiWi-cards. These boards can capture via HDMI, so there are ports for that signal. Edit: Yes, this boards can capture the audiosignal too.
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