Video input

Video input is the process of capturing full-motion images and storing them on a computer’s storage medium such as a hard disk or DVD. Some video devices record video using analog signals.
Computers, by contrast, use digital signals. To enter video from an analog device into a personal computer, the analog signal must be converted to a digital signal. To do this, plug a video camera or other analog video device in a video capture port on the system unit.
One type of adapter card that has a video capture port is a video capture card, which converts an analog video signal into a digital signal.
Most new computers are not equipped with a video capture card because not all users have the need for this type of adapter card.
 
A digital video (DV) camera, by contrast records video as digital signals instead of analog signals. Many DV cameras can capture still frames, as well as motion. 

To transfer recorded images to hard disk or DVD, users connect DV cameras directly to a USB port or a FireWire port on the system unit. Thus, the computer does not need a video capture card. After saving the video on a storage medium, you can play it or edit it using video editing software (Figure 5-16).
 A Web cam, also called a PC video camera, is a type of digital video camera that enables a home or small business user to capture video and still images, send e-mail messages with video attachments, add live images to instant messages, broadcast live images over the Internet, and make video telephone calls.
 
Attached to the computer’s USB port or FireWire port, a Web cam usually sits on top of the monitor. Some notebook computers have built-in Web cams. Some Web sites have live Web cams that display still pictures and update the displayed image at a specified time or time intervals, such as 15 seconds. A streaming cam has the illusion of moving images because it sends a continual stream of still images.

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