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MOTION VIDEO

Videotape recording has basically replaced motion-picture film making. Motion video has a number of advantages compared to motion-picture coverage. Some of these advantages are as follows:

  • A videotape camera can record black and white as well as color.
  • No time-consuming film processing is required and recordings can be played back immediately.
  • When necessary videotape may be partially or completely erased and used again for several more recordings. It can be played back numerous times and may be stored indefinitely.
  • Videotape is edited or assembled more quickly than film.
  • Videotapes are duplicated and distributed easily to other locations.

A video camera is optically similar to a movie camera, except it does not use film. Considering the technical complexity of a video camera, it is fundamentally simple. To understand clearly motion video, you must be familiar with some key terms. These terms will be seen commonly in all publications pertaining to video.

KEY TERMS AGC-Automatic gain control. Regulates the volume of the audio or video light levels automatically within a camcorder.

Analog-An analog signal that fluctuates exactly like the original stimulus (examples, sweep second-hand clock, phonograph player).

Ambient Sound-Background sound or "wild" sound. Sound that surrounds the scene or location, received by the microphone and recorded onto magnetic tape.

Aspect Ratio-The ratio of the height to the width of the film or television frame. Three units high to four units wide (3:4).

Audio Track-The area of a videotape that is used for recording audio information.

Beam Splitter-An optical device within a color camera that splits the white light into three primary colors: red, green, and blue.

Camcorder-A portable video camera with videotape recorder (VTR) and a microphone attached to form a single unit.

Capstan-An electrically driven roller that rotates and transports the videotape past the recorder heads at precise and fixed speeds.

CCD-Charged-coupled device, also called a chip. A small, solid state (silicon resin) imaging device used in a video camera instead of camera pickup tubes. Inside the chip, image sensing elements translate the optical image into a video signal.

Character Generator-An electronic device used to create words or graphics that may be electronically inserted or "keyed" over the video picture.

Color Bars-A color standard used by the television industry for the alignment of cameras and videotape recordings.

Component-The processing of RGB (red, green, blue) channels as three separate channels.

Composite Signal (Y/C)-(Also called NTSC signal) The video signal in which luminance "Y" (black and white) and chrominance (red, green, blue) and sync information are encoded into a single signal.

Control Track-The area of the videotape used for recording the information necessary to synchronize the all elements during playback.

Digital VTR-A videotape recorder that translates and records the analog video signal in digital form. Dub-Duplication of an electronic recording. Dub is always one generation away from the original recording.

Dropout-A loss of part of the video signal, which appears as white glitches. Caused by dirty VTR heads or poor quality videotape.

Field-Scanning lines in one-half of one video or television frame. There are two fields (one odd and one even) in a frame. One field equals 262.5 scanning lines, which create a total of 525 standard television lines or one frame. Also known as the NTSC signal (U.S. TV system).

Frame-The smallest unit in television or film, a single picture. A complete scanning cycle of the two fields occurs every 1/30 second. A frame equals 525 scan lines.

Gain-The level of amplification for a video or audio signals. Increasing the video gain increases the picture contrast.

Generation-The number of dubs or copies away from the original recording. The greater the number of generations, the greater the loss of picture quality.

Heads-A small assemble within an audio or video recording system, which can erase, record or playback the signal in electromagnetic impulses.

Helical Scan, or Helical VTR-(Also called slant track). A videotape recording or a videotape recorder in which the video signal is put on tape in a slanted, diagonal way. Because the tape wraps around the head drum in a spiral-like configuration, it is called helical.

Noise-Unwanted sounds or electrical interference in a audio or video signal. In the audio track, there is a hiss or humming sound. In the video picture the interference appears as "snow."

NTSC-National Television Standards Committee. U.S. standards for television or video signal broad-casting. Also known as the composite signal (Y/C).

Pickup Tube-The imaging device in a video camera that converts light into electrical energy (video signal).

Pixel-The smallest single picture element with which an image is constructed. The light-sensitive elements in a CCD (chip) camera.

Preroll-To start a videotape and let it roll for a few seconds before it is put in the playback or record mode so that the electronic system has time to stabilize.

RGB-The separate red, green, and blue color (chrominance), or "C," video signals.

Slant Track-Same as helical scan.

Time Base Corrector (TBC)-An electronic accessory to a videotape recorder that helps make playbacks or transfers electronically stable. A TBC helps to maintain picture stability even in dubbing-up operations.

Video Cassette-A plastic container in which a videotape moves from a supply reel to a take-up reel. Used in all but the 1-inch VTRs. VTR-Videotape recorder or recording. Includes video cassette recorders.

Y/C-The separate processing of the luminance (Y) and chrominance (C) signals.