The purpose of this white paper is to provide a semi technical explanation of what a capture card is and some common uses for such. (links from this page are to Wikipedia)
Other common names for a Capture Card are:
Frame Grabber
Video Capture Card
Video Acquisition Device
Video input device
Capture Board
Scope of this article:
There are “commercial grade” and “consumer grade” capture cards, this paper will be commercial grade focused but general principals will apply to both. References will be to commercial grade devices and software.
Definition:
A capture card is an electronic device that accepts a single or multiple video or video and audio signal(s), digitizes them and makes the captured signals available to other hardware or software for further processing such as display on a monitor connected to host system, compressing, streaming, transmitting, recording or some combination of above.
A capture card is typically a PCI or PCI Express type printed circuit board that resides in a host microcomputer systems slot. So a capture card is a component of a larger system that performs some specific function. (Note: There are standalone capture devices that typically interface with microcomputers via some data interface connection such as USB. This paper will not explore standalone devices, rather the card or board types.) Depending on the manufacturer of the capture card, multiple cards can reside in a single host system allowing multiple concurrent video/audio streams to be captured and processed. In addition various capture cards can accept different analog or digital signal types. e.g. HDMI with digital embedded audio, DVI digital or analog, VGA analog, composite video, component video, serial digital video (SDI), DisplayPort etc.
Picture of a Capture Card:
A Datapath VisionRGB -E2s Capture Card
Datapath Sound Cards & Media Devices Driver
Datapath has added a pair of advanced capture cards to its VisionSC range. The latest products from the advanced graphics display technology specialist are the VisionSC-HD4+ high bandwidth, four channel HDMI capture card and the VisionSC-SDI4, the company’s first four-channel 3G-SDI capture card. Voultar's Double Penetration SD is essentially a splitter designed to be paired with Datapath E1/E1S capture cards and handles 240p/480i 15 Khz signals. This device will split a signal into two outputs which is a very convenient way of dealing with the input only on Datapath E1/E1S capture cards. Many of DataPath’s cards and services are auto-substantiated and purchases are verified at the point-of-service. This means that qualified expenses for FSAs and HSAs, and at doctors’ offices or other verified merchants, are authenticated when those items and services are purchased.