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video capture board

An expansion card that provides inputs and outputs for analog and digital video. It is used to link video cameras, camcorders and tape decks to the computer for editing. Analog video inputs are converted to digital YUV or RGB color spaces for processing and converted back to analog formats for analog destinations. Capture boards that support SDI connections are used for high-end video editing. See SDI.

A High-End Video Capture Board
Blackmagic Design's DeckLink HD card supports standard and high definition and all major analog and digital sources and destinations. The four BNC connectors on the card (top) are SDI links, and all the cables (bottom) plug into the 15-pin D-Sub connector on the card. (Images courtesy of Blackmagic Design Pty. Ltd,


(1) See software-defined infrastructure, Single Document Interface, Strategic Defense Initiative and Switched Digital International.

(2) (Serial Digital Interface) A hardware interface for transmitting digital video. SDI uses a high grade of coaxial cable and a BNC connector with Teflon insulation. It also supports optical fibers with ST, SC and FC connectors. Following are the common formats transmitted over SDI. See ITU-R BT.601, BNC connector, fiber-optic connectors and serial interface.

 SD-SDI                  Aspect  Transfer
 (Standard Definition)   Ratio   Rate
 Digitized NTSC (4FSC)    4:3    143 Mbps
 Digitized PAL (4FSC)     4:3    177 Mbps
 Component ITU-R BT.601   4:3    270 Mbps
 Component ITU-R BT.601  16:9    360 Mbps

 HD-SDI (High Definition)  See HD-SDI.
 Component ITU-R BT.709  16:9  1,485 Mbps
 Dual-link (two cables)        2,970 Mbps

 3G-SDI (3 Gbps)
 One-cable version of HD-SDI   2,970 Mbps

Blackmagic SDI Capture Board
Two sockets are input, and two are output. At 4:2:2 color sampling, SDI uses one line for in or out. However, HD-SDI at 4:4:4 requires two lines. See chroma subsampling. (Image courtesy of Blackmagic Design Pty. Ltd,

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