Audio/Video Signal Protocols

AES EBU Digital Audio

AES/EBU (Audio Engineering Society/European Broadcasting Union) is a balanced, digital audio transfer standard that uses an XLR connector with a single cable carrying  left-channel and right-channel audio data.


(See Y/Pb/Pr)


Composite Video is a single signal which carries both the chrominance (color) and luminance (brightness) components of a video signal, along with sync information, on a single wire. Unlike an RF signal, a composite video signal does not need to be demodulated to be understood by a video display. Like other baseband video formats, a composite video signal does not carry any audio content, which must be handled separately.


(see Composite) Composite video is sometimes designated by the acronym CVBS. There is some confusion about the expansion of this acronym with some commonly used alternatives being: "Colour, Video, Blank & Sync", "Composite Video Baseband Signal", "Composite Video Burst Signal" or "Composite Video with Burst & Sync".


DVI (Digital Video Interface) is a video interface standard used primarily with flat panel LCD monitors and high-end video graphics cards. DVI-D and DVI-I formats can use Single or Dual link connectors with the dual link providing an increase in speed and signal quality. DVI Digital and Analogue formats are non-interchangeable.


DVI-A (Analogue format) is  just the RGBHV signal format using a different connector.


DVI-D (Digital format) is a parallel digital standard having up to seven balanced lines. In addition to carrying the video signal, five conductors are used for carrying other information. Because this is a digital rather than an analogue signal, it can only be converted to another format through a device that is equipped to decode the digital bit-stream and render it in analogue form.


DVI-I (Integrated Analogue and Digital format) is capable of transmitting either a digital-to-digital signal or an analog-to-analog signal.

EIA 770.3

(see Y/Pb/Pr)


Is a "Red Book" standard for digital audio (stereo or multi-channel) that uses light from an LED "transmitter" as the source. (Also see TOSLINK).


(see IEEE1394). Apple's®  trademarked name for the IEEE1394 standard.


High Definition Media Interface is a signal format, backwardly compatible with DVI-D and employing the same encoding/decoding scheme. Video is kept in uncompressed digital format and 8-channel audio is offered. Combines a digital audio and a digital video cable into a single connector. The video signals on HDMI are backwardly compatible with DVI-D.


An external bus standard that supports data transfer rates of up to 400Mbps (1394a) and 800Mbps (1394b). It also supports isochronous data - delivering data at a guaranteed rate, making it ideal for devices that need to transfer high levels of data in real-time, such as video devices.


(see IEEE1394). Sony's®  proprietary name for the IEEE1394 standard.


RF, or Radio Frequency, is the type of signal that comes through the air by antenna or through a cable TV connection. In standard-definition broadcast and analogue cable, a composite video signal and accompanying audio are mixed, at the transmitting end, with high-frequency radio waves, and are broadcast through the air or distributed through a cable system. To be viewed on a display, these signals have to be separated from the other channels in the line and converted to unmodulated "baseband" video and audio signals using a television tuner (found in any conventional television set or VCR). RF is used as a distribution medium because (1) it propagates through the air very well, making it suitable for over-the-air broadcast, and (2) many video signals can be modulated at many different frequencies, it's possible for us to have many "channels" available simultaneously without having them interfere with one another.


The original "component video" was RGB, which appears in three principal varieties, each requiring a different number of connections. The most common type is RGBHV, with five lines: one for red, one for green, one for blue, one for the horizontal sync and one for the vertical sync. RGBHV is the standard used in VGA and other types of analogue PC computer monitors. DVI-A is the same signal format but using a different connector. RGBS, having four connections, differs from RGBHV in having the vertical and horizontal sync combined on a single channel. RGsB, or "sync-on-green," places the sync information on the green channel--not unlike, but still not compatible with, Y/Pb/Pr component video.


SCSI stands for "Small Computer System Interface", and is a standard interface and command set for transferring data between devices on a computer bus, It's most commonly used for hard-drives and tape storage devices, but also connects a wide range of other devices, including DVD drives.


SDI is "Serial Digital Video", run in an unbalanced line and used primarily in professional production environments. The technical standard is maintained by the Society of Motion Picture and Television Engineers (SMPTE) as SMPTE 259M. Uses standard single 75 Ohm coaxial cable with a single BNC connector on each end.


SPDIF (Sony/Philips Digital Interface) is a CD "Red Book" standard digital audio transfer file format, for either stereo or multi-channel sound. 


S-video (Super Video) is a format which splits the chrominance (color) and luminance (brightness) separately onto two lines, "C" and "Y," each requiring its own coaxial cable with the sync pulses carried on the luminance line. Typically uses a 4-pin Mini DIN plug/socket.


(see EIJA Optical). TOSLINK (Toshiba Link) is Toshiba's proprietary name.


Universal Serial Bus (USB) is a hardware interface for low-speed peripherals and MPEG-1 and MPEG-2 digital video. Uses a 4-wire USB cable terminated with type-A or type-B USB connectors.


Uses the RGBHV standard which is a variant of RGB, with five lines: one for red, one for green, one for blue, one for the horizontal sync and one for the vertical sync and is the standard used for analogue PC computer monitors.


(see Y/Pb/Pr) 


In Y/Pb/Pr Component Video, there is a luminance channel, "Y," which carries the luminance along with the sync pulses, and two color-difference channels, which carry signals representing Blue minus Luminance (B-Y, or Pb) and Red minus Luminance (R-Y, or Pr). From these signals, the display device separates out the sync information and reconstitutes the red, green and blue components of the picture. Just as s-video requires two signal-carrying wires instead of one, component video requires three  connections color-coded green (Y, or Luminance), blue (Pb) and red (Pr). RGBHV will usually, though not always, be color-coded red, green, blue, yellow (horizontal sync) and white (vertical sync).


(see Y/Pb/Pr)

Use our audio/video interconnect reference page to identify the type of connectors commonly used to terminate a particular cable. Our suggested color code for audio/video interconnects that identifies the role of a particular cable, is based on common industry practice. Our cables reference page to identify the different cable types commonly used for audio/video installations.


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