Audio / Video Tutorial
What are Audio / Video products?
Audio/Video products consist of cables, adapters, converters and extenders which utilize various video and audio interfaces to transmit and receive video and / or audio signals.
How are Audio / Video products used?
The primary function of Audio/Video cables is the interconnection between a signal generating device such as a CPU (Central Processing Unit) and a display device such as a monitor. The interfaces used to make this connection have evolved over the years and include EVC, HD15, DVI, HDMI and DisplayPort to name a few. Also there are Audio/Video converters which convert two different technologies such as HDMI to DisplayPort etc. Audio/Video extenders amplify, extend and repeat Audio/Video signals.
Where are Audio / Video products used?
Audio/Video products are used in a wide variety of video and/or audio signal transmission applications found in both office and home environments from business computers to home entertainment systems. Additionally these products are used in government and military applications as well as Industrial and process control environments.
Audio / Video Terms
Analog Signals: Both video and audio signals that are continuously varying in level are said to be analog.
Attenuation: A reduction in the strength of a signal.
Bandwidth: The difference between the upper and lower usable limits of a band of frequencies.
Baseband: Unmodulated video or audio signals with an exclusive transmission path.
Chroma: The color portion of a video signal “C”.
Composite Sync: A combination of horizontal and vertical sync pulses.
db: A logarithmic unit of measure where 3db represents a doubling or halving the power level from a given starting point.
DDC: (Data Display Channel) is a standard that defines communication between a monitor and a host system.
DVI: Digital Video Interface
Digital Signals: Data presented as discrete values i.e. On/Off or Binary.
HDMI: High Definition Multimedia Interface. All digital audio and video.
Luma: The brightness portion of a video signal (“Y”).
Pixel: A single point on a display.
Resolution: The density of pixels in a given area typically expressed as the horizontal x vertical values, (ex. 640x480).
Refresh Rate: Also referred to as scan rate. It is the number of times in one second (Hz) that the electron beam travels across the screen horizontally from one scan line to the next.
RGB: Red, Green and Blue.
SVGA: Super Video Graphics Array.
S-Video: A video signal that separates the “Y” or Luma and “C” or chroma information.
Standard VGA vs. VGA with DDC™ Comparison
A quick examination of the pinout tables listed shows the use of pins 9 and 15 in the right hand column.
A DDC enabled port can be easily identified by the royal blue color of the insulator. New monitors with this implementation require the presence of pins 9 and 15 to operate correctly.
Various DVI Configurations
Shown are a number of DVI connector interfaces that can be identified by the pin configurations. They include DVI-A (analog only), DVI-D (digital only) and DVI-I (analog and digital). In addition, single link and dual link configurations exist for both DVI-D and DVI-I. Shown are the major configurations illustrating the distinguishing features for each type of DVI interface.
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Analog and Digital
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Analog Only
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DVI-A
One row of 5 pins, one row of 3 pins and one row of 4 pins with two contacts above and below the flat blade. |
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Digital Only
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DVI-I Single Link
Three rows of 6 pins and two contacts above and below the flat blade. |
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DVI-D Single Link
Three rows of 6 pins and no contacts above or below the flat blade. |
DVI-I Dual Link
Three rows of 8 pins and two contacts above and below the flat blade. |
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DVI-D Dual Link
Three rows of 8 pins and no contacts above or below the flat blade. |
Common Computer Interfaces
The interconnection between a Central Processing Unit (CPU) and the Monitor, Mouse, Keyboard and Speakers found in a typical desktop computer set up uses a number of different interfaces. Below is a list of some of the more common types.
Major Digital Interfaces
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