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Generation
The number of times an electronic signal is copied. First generation refers to the original material, usually in its unedited form. The edited videotape made from this material is considered to be second generation. All subsequent copies or duplicates are one generation removed from the material from which they were copied. Care must be taken to ensure that distortion and other defects do not degrade the video and audio quality.

With analog duplication techniques, distortion and other noticeable problems occur after only a few generations, typically 7 or 8. In the digital domain, a minimum of 20 generations may be made before any defects are noticeable.

Hard Copy
Also called a printout. A paper printout of computer data. In editing, a printout of an EDL. topˆ

HDTV
A television system that offers more than twice the picture resolution of a conventional television. The SMPTE 240-M system contains 1125 horizontal scan lines per frame while conventional television has 525 lines. The screen aspect ratio is typically 16:9 (1.78:1) as opposed to 4:3 (1.33:1) for standard television images.

HDTV videotape, when converted to film, compares favorably with the quality of direct optical photography using motion picture film cameras. topˆ

Helical Scan (also known as slant track)
VTR or VCR recording format that wraps the tape around the video scanner in a helix pattern. There are essentially two helical scan formats, the alpha wrap and the omega wrap. The alpha wrap was the first format to be used in early helical scan VTRs. The disadvantage of this format is that it requires the videotape to be wrapped 360 degrees around the scanner. This is cumbersome especially if the tape must be loaded or unloaded from the VTR in the middle of the reel.

Current helical scan VTRs and VCRs use an omega wrap. This configuration wraps the tape around the drum in a horseshoe or U pattern, allowing easy threading or removal of the tape. topˆ

Heterodyne Color Recording (color under)
A method of recording that translates the encoded chroma signal to a lower video frequency so that color recording may be effected in a limited bandwidth. It also electronically compensates for the timing jitter inherent in helical scat recorders. Used in consumer and industrial VCRs. topˆ

Hue
A specific color wavelength in the visible light spectrum, an attribute of color perception. Flesh tones, for example, may be changed by adjusting the hue control (sometimes marked color phase) on a television receiver or monitor. topˆ

Interlace
The combining of two sequential television field that make up a complete frame in the NTSC system. Field 1 contains the odd numbered scan lines, field 2 the even numbered line. When combined by interlacing, line 2 falls between 1 and 3, line 4 falls between 3 and 5, and so on. Interlaced scanning solves the problem of flicker at reasonable frame rates. An image repetition rate of less than 48 per second appears to flicker under typical viewing conditions. Interlacing provides a field repetition rate of 60 per second, well above the flicker threshold. The PAL system, having a field rate of 50 per second, often exhibits flicker to those not accustomed to it. Motion picture projection gets around the problem by using a 2-blade shutter assisted by viewing in a relatively dark room. Interlace bring with it motion artifacts that are noticeable at times.

While exhibiting superior motion rendition compared to 24 frame may show a double image particularly noticeable in sporting events or other fast action because of the 1/60th of a second offset between fields. The equalizing and vertical serrated pulses in the sync signal are essential to achieve perfect interlace. topˆ

 

 

 

 


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