About Video Interfaces, Signals, and Connectors

There are many types of video interfaces, signal formats, and connectors that can be used when setting up your system.

Video Interfaces

Final Cut Pro allows you to use a wide variety of video interfaces for capture and output. The following sections show examples of the most common types of video interfaces available.

FireWire for DV

You can use the built-in FireWire port on your computer to capture and output to almost any DV device, including DV, DVCAM, DVCPRO, DVCPRO 50, and DVCPRO HD devices.

Figure. Diagram showing a computer, camcorder, and FireWire cable connector.

In this configuration, you need only your computer and a supported DV device. For more information, see Connecting DV Video Equipment.

Figure. Diagram of a computer, DV VTR device, and FireWire connectors.

FireWire for Uncompressed Digital Video

Interfaces such as the AJA Io connect to your computer via FireWire. However, instead of transferring compressed DV signals, the AJA Io transfers an uncompressed component 4:2:2 signal via FireWire. The AJA Io has a wide range of digital and analog connectors, as well as RS-422 device control.

Figure. Diagram showing a computer and an uncompressed digital video device with FireWire connector.

Important: Although this type of video interface uses FireWire, it is not used to connect DV devices. If you want to capture or output DV video, you can connect your DV device directly to the FireWire port on your computer.

Figure. Diagram showing a computer connected to an AJA Io device and the AJA IO device connected to an analog or digital VTR.

PCI Express Video Interface Card

If you are using professional analog or digital formats (either standard definition or high definition) without native FireWire connectivity, you need to purchase and install a PCI Express video interface card to connect your video deck or camcorder to your computer. Many PCI Express interface cards come with a breakout box where video, audio, and perhaps even 9-pin remote connectors are located (rather than on the PCI Express card itself). Interface cards are also referred to as video cards or capture cards. This is not the same as the video graphics card used to send signals to your main computer display.

Figure. Diagram showing a PCI video interface card placed in a computer.

PCI Express cards allow you to capture and output video with high data rates, such as uncompressed standard definition (SD) and high definition (HD) video. PCI Express cards are necessary for high-end applications such as compositing, online editing, and uncompressed video editing. Many PCI Express cards have BNC or RCA connectors mounted directly on the back of the card. In this configuration, you connect your video equipment directly to the PCI Express card connectors on the back of your computer.

Figure. Diagram showing a computer connected to an analog or digital VTR via a BNC connector.

Many PCI Express cards aren’t big enough to fit all of the necessary video and audio connectors. In these situations, a breakout box is connected to the PCI Express card via a multipin connector on a long cable, and the connectors are accessible on the breakout box instead of the back of the PCI Express card. A breakout box is also useful because it allows you to place the connectors somewhere more convenient than the back of your computer, such as an equipment rack or a desktop.

Figure. Diagram showing a computer connected to a breakout box, which is connected to an analog or digital VTR.

USB Video Interface

USB video interfaces cannot support the high data rates required for professional video use, so they are not commonly used. USB video interfaces are usually used for converting analog video sources to a digital signal for capture.

Figure. Diagram showing a computer connected to a USB interface, which is connected to an analog VTR.

Video Signals and Connectors

When you capture and output, the type of video signal you use to connect your equipment is a critical factor that goes into determining the quality of your video. Video camcorders, decks, and monitors can use different types of signals, depending on the environment they are intended for. Consumer equipment usually has limited video signal choices; professional equipment gives you the greatest range of options.

For more information, see Video Formats.

Composite

Composite is the lowest common denominator of video signals. A composite signal runs all color and brightness information on a single cable, resulting in lower-quality video compared to the quality of other formats. Nearly all video devices have a composite input and output. This format uses a single RCA or BNC connector.

In professional editing environments, composite video signals are most commonly used for troubleshooting, for menu outputs, and for low-quality preview monitoring. For consumer and home use, composite signals are often used to connect VCRs or DVD players to televisions.

Figure. Diagram of an RCA connector and a BNC connector.

S-Video

S-Video, also known as Y/C, is a higher-quality video signal used by high-end consumer video equipment. The image looks sharper and has better color than a composite video image because S-Video keeps the color and brightness information separate on two cables. Most low-cost analog-to-digital video interfaces have S-Video as their highest-quality video connector. Use care when working with S-video connectors; the four delicate pins can be bent easily.

Figure. Diagram showing an S-Video connector.

Component YUV and Component RGB

Professional video equipment, such as Betacam SP decks, has component YUV (Y′CBCR) video inputs and outputs. Component YUV separates color and brightness information into three signals, which keeps the color quality more accurate than that of other systems. Component YUV is as good as analog video gets. High-end consumer devices, such as DVD players and televisions, have increasingly begun to support component YUV.

Note: Another form of component video, component RGB, is not as widespread on professional equipment as component YUV.

Both component YUV and RGB signals use from three to five connectors. You can use three BNC connectors, plus a fourth (typically labeled “genlock” or “house sync”) to send a timing signal. Sync can also be embedded in the Y or G part of the signal (using three connectors), a separate composite signal on a fourth connector, or separate H and V drive signals (using five connectors). See your equipment’s documentation for more information.

Figure. Diagram showing component connectors and a YUV/RGB switch.

SCART

Consumer PAL equipment sometimes has a special connector called a SCART connector. A SCART connector has multiple pins that run composite, component RGB, and stereo audio in one bundle. SCART input or output can be broken up into individual connections using special adapters available from video and home electronics stores.

Figure. Diagram showing a SCART connector.

FireWire 400

FireWire 400, also called IEEE 1394a or i.LINK, is the consumer and professional standard for formats such as DV, DVCAM, DVCPRO, DVCPRO 50, DVCPRO HD, and HDV. FireWire is an inexpensive and easy way to capture and output high-quality digital video using a variety of camcorders and decks and is capable of data rates as high as 400 Mbps. Standard FireWire cables can be up to 4.5 meters long.

There are two kinds of FireWire connectors: a 4-pin connector (typically found on video equipment such as camcorders or decks) and a 6-pin connector (used for computer equipment). However, some newer video equipment uses the 6-pin connector, and some video interfaces use the 4-pin connector. See your equipment’s documentation for more information.

Figure. Diagram showing FireWire 400 (6-pin) and FireWire 400 (4-pin) connectors.

FireWire 800

FireWire 800, also called IEEE 1394b, is the next generation of FireWire after IEEE 1394a, a higher-bandwidth version capable of data transfer speeds of up to 800 Mbps. FireWire 800 is also capable of supporting cable distances of up to 100 meters.

9-pin-to-4-pin and 9-pin-to-6-pin FireWire 400 to FireWire 800 cables are available to connect older devices to a FireWire 800 interface.

Figure. Diagram showing a FireWire 800 9-pin connector.

Note: FireWire 800 is commonly used to connect hard disks and other data peripherals to your computer, but this connector is rarely used to connect video devices.

SDI

Serial Digital Interface (SDI) is the standard for high-end, uncompressed digital video formats such as D1, D5, and Digital Betacam. Many devices can send both video and audio data through a single SDI connection.

Figure. Diagram showing a BNC connector.

HD-SDI

High Definition Serial Digital Interface (HD-SDI) is a higher-bandwidth version of SDI designed for the extremely high data rates required by uncompressed HD video. Like SDI, HD-SDI is capable of sending both video and audio through a single connection. The following decks have HD-SDI interfaces: DVCPRO HD, D-5 HD, and HDCAM decks.

Some devices provide even higher data rates by pairing two HD-SDI channels together (known as dual-link HD-SDI). Uncompressed HD RGB video and other digital cinema formats can be transmitted using dual-link HD-SDI.

SDTI

Serial Digital Transport Interface (SDTI) is based on SDI, allowing native video formats to be sent in real time within an SDI video stream. SDTI does not define a specific video signal format but instead uses the structure of SDI to carry any kind of data. This allows video facilities to use their existing SDI patchbays and routers to transfer other native video formats, or transfer any kind of data. For example, some DV decks can transfer DV via SDTI, which means native DV can be transferred long distances over existing coaxial cable instead of via the usual FireWire connection. Other formats, such as HDCAM and MPEG, can also be transferred via packets within an SDTI transport stream.

VGA

VGA interfaces use a 15-pin D-subminiature connector to transfer analog RGB video and sync information between computers and computer CRT displays or video projectors. This connector and signal format is being replaced by newer display formats such as DVI and HDMI. However, adapters are available to convert between DVI and VGA.

Figure. Diagram showing a VGA connector.

DVI

Digital Visual Interface (DVI) transfers full-resolution analog or digital signals between computers or HD video devices and flat-panel displays or projectors. DVI connectors have up to 24 pins plus 4 additional pins for analog signals. Not all devices use all pins, so read the documentation included with your equipment before purchasing DVI cables and making connections.

Figure. Diagram showing a DVI connector.

DVI supports single- and dual-link connections. Single-link DVI connections are limited to 2.6 megapixels with a refresh rate of up to 60 Hz. Dual-link DVI connectors extend the number of pixels that can be transferred per second to drive larger displays.

Figure. Diagram showing single-link and dual-link DVI-I connectors and single-link and dual-link DVI-D connectors.

HDMI

High Definition Multimedia Interface (HDMI) supports both digital television and computer signals and can also include multiple digital audio channels. HDMI devices are compatible with single-link digital DVD signals via an adapter, although no audio or additional metadata can be included. Many HD display devices and digital television set-top boxes include HDMI connectors.

Figure. Diagram showing an HDMI connector.