        |
 
| Learn About Alpha's Services |
|
         |
|
|
|
SELECTED VIDEO DEFINITIONS
ADA: Analog Distribution Amplifier. A device that takes in one signal and distributes it to several outputs without "tying" those outputs together (buffered).
ADAPTER: A linking device that allows two dissimilar devices to connect physically, and/or communicate electronically, such as VGA to Mac adapter.
ADC: Analog-to-digital converter. A device used to convert analog signals to digital signals.
ADDITIVE COLOR PROCESS: Also called "RGB". A color generation process used in video that combines red, green and blue to make all colors. All three colors (red, green and blue) at 100% combine to make white on a video screen; the absence of all three colors (0%) makes black.
BALANCED AUDIO: method that uses three conductors for one audio signal. They are plus (+), minus (-) and ground. The ground conductor is strictly for shielding, and does not carry any signal. Also called "differential audio".
COMPONENT VIDEO: Color television systems start with three channels of information: red, green, and blue (RGB). In the process of translating these channels to a single composite video signal, they are often first converted to Y, R-Y, and B-Y. Both 3-channel systems, RGB and Y, R-Y, B-Y, are component video signals. They are the components that eventually make up the composite video signal. Higher quality program production is possible if the elements are assembled in the component domain.
COMPOSITE VIDEO: An all-in-one video signal comprised of the luma (black and white), chroma (color), blanking pulses, sync pulses and color burst.
HDTV: High Definition Television. HDTV refers to a complete product/system with the following minimum performance attributes: a receiver that receives ATSC terrestrial digital transmissions and decodes all ATSC Table 3 video formats; a display scanning format with active vertical scanning lines of 720 progressive (720p), 1080 interlaced (1080i), or higher; aspect ratio capabilities for displaying a 16:9 image; receives and reproduces, and/or outputs Dolby Digital audio.
SCALING: Scaling is changing the size of an image without changing its shape. Scaling may be required when the image size does not fit the display device. An example of scaling down would be to take a 640 x 480 resolution TV image and display it as a smaller picture on the same screen, so that multiple pictures can be shown at the same time. (Such as with picture-in-picture, PIP.) If the original image is scaled down to a resolution of 320 x 240, this is 1/4 of the original size, allowing four pictures to be shown on the same screen at the same time.
An example of "scaling up" would be to take a lower resolution image (e.g. 800 x 600 = 480,000 pixels) to display it on a higher resolution (1024 x 768 = 786,432 pixels) device. The number of pixels is the product of the two numbers. This means that pixels must be created. The problem is, create them from what? There are many different methods for image scaling, and some produce better results than others.
SCAN CONVERTER: Also called "video converter" or "TV converter", a scan converter is a device that changes the scan rate of a source video signal to fit the needs of a display device. Examples: computer-video to NTSC (TV), or NTSC to computer-video.
S-VIDEO: A composite video signal separated into the luma (?Y? is for luma, or black and white information; brightness) and chroma (?C? is an abbreviation for chroma, or color information). Also referred to as Y/C. Typical connectors are 4-Pin DIN or BNC.
VGA: Video Graphics Array. The computer video outputs to a 15-pin HD connector and has a horizontal scan frequency of 31.5kHz and a vertical frequency of 70Hz. VGA has a pixel by line resolution of 640 x 480. SVGA, XGA, and UXGA represent much higher resolution. They all wire the same at the HD15-pin connector.
|
|
        |
