[rec.video] TN32--HDTV and ATV Glossary

poynton@vector.Sun.COM (Charles A. Poynton) (03/07/90)

TN32--High-Definition Television (HDTV) and Advanced Television (ATV) Glossary

(c) 90/03/03 
Charles A. Poynton 
Sun Microsystems, Inc.

525-line, 625-line Television Terms

Scanning Standard. The parameters associated with raster scanning of a pickup
  device or a display device, or the associated signal in a channel or a
  recording device. A scanning standard is denoted by its total line count,
  field rate and interlace ratio (e.g. 525/59.94/2:1 or 625/50/2:1). 

Colour Standard. The parameters associated with transmission of colour
  information, for example RGB, YCbCr or MAC component colour standards or NTSC,
  PAL or SECAM composite colour standards. 

525/59.94/2:1. A scanning standard used primarily in North America and Japan,
  having 525 total lines per frame (of which approximately 484 contain picture
  information), a field rate of 59.94 Hz and interlace. Without the "/2:1"
  notation, interlace is implicit. A raster notation such as 525/59.94 does not
  specify colour coding; colour in 525/59.94 systems is commonly conveyed in the
  studio using either RGB or YCbCr components and encoded for transmission using
  the composite NTSC method. Known internationally as CCIR System M. Often
  colloquially referred to as 525/60; often incorrectly called NTSC (which
  properly refers to a colour standard, not a scanning standard). 

625/50/2:1. A scanning standard used primarily in Europe and Asia, having 625
  total lines per frame (of which 576 contain picture information), a field rate
  of 50 Hz and interlace. Without the "/2:1" notation, interlace is implicit. A
  raster notation such as 625/50 does not specify colour coding; colour in
  625/50 systems is commonly conveyed in the studio using RGB or YCbCr
  components and distributed by satellite using the MAC system, or distributed
  by terrestrial VHF/UHF television using the composite PAL method (although
  France, the USSR and certain other countries use SECAM). Often incorrectly
  called PAL or SECAM (which properly refer to colour standards). 

NTSC (National Television Systems Committee). (1) The group that in 1941
  established 525-line, 60.00 Hz field rate, 2:1 interlaced monochrome
  television in the United States. Now properly referred to as NTSC-I. (2) The
  group, more properly referred to as NTSC-II, that in 1953 established 525-line
  59.94 Hz field rate, 2:1 interlaced, composite colour television signals
  in the United States. (3) A method of composite colour encoding based on
  quadrature modulation of B-Y and R-Y colour difference signals onto a colour
  subcarrier and adding the resulting chroma signal to luminance. Used only in
  525/59.94 systems, with a subcarrier frequency of 455/2 times the horizontal
  line rate, i.e. about 3.579545 MHz. (4) Often used incorrectly to denote
  525/59.94 scanning. 

PAL, Phase Alternate Line. A composite colour standard similar to NTSC, except
  that the R-Y-axis subcarrier reference signal inverts in phase at the
  horizontal line rate. Commonly used in 625/50 systems with a subcarrier
  frequency of 4.43361875 MHz, but also used in 625/50 systems with a subcarrier
  of 3.58205625 MHz in the PAL-N system (e.g. Argentina); and with 525/59.94
  scanning and a subcarrier frequency of 3.575612 MHz in the PAL-M system (e.g.
  Brazil). Often used incorrectly to denote 625/50 scanning. 

SECAM, Sequential Couleur avec Memoire. A composite colour standard based on
  line-alternate B-Y and R-Y colour difference signals, frequency modulated onto
  a colour subcarrier. In use only with 625/50 scanning (e.g. France, USSR). 

Component Colour. A video system that conveys three colour component signals
  independently. Examples are RGB, YCbCr and MAC. 

Composite Colour. A video system that uses the spectral interleaving
  (frequency interleaving) technique to encode (combine) luminance and colour
  information into a single signal. The three colour components are
  simultaneously present in the composite signal. Examples are NTSC, PAL and
  SECAM. 

S-video, S-connector, YC3.58, YC4.43. An interface that conveys luminance and
  quadrature modulated chrominance as two separate signals on a specific four-
  pin mini-DIN connector. There are only two types of S-video: YC3.58, which has
  a 525/59.94 raster and chrominance modulated as in NTSC and YC4.43, which has
  a 625/50 raster and chrominance modulated as in PAL. S-video is a form of
  component video, in that the three components are conveyed independently
  (although the colour difference components have limited bandwidth). 

MAC, Multiplexed Analog Component. A colour standard that transmits three
  colour components, usually in YCbCr form, in time-compressed serial analog
  form. Used primarily with 625/50 scanning. 

2:1 Interlace. A scanning standard in which alternate raster lines of a frame
  are displaced vertically by the scanning line pitch and displaced temporally
  by half the frame time, to form an odd field and an even field. Also called
  2:1 Interlace. Examples are 525/59.94/2:1, 625/50/2:1, 1125/60.00/2:1. Systems
  with high order interlace have been proposed but none have been introduced in
  practice, so interlace implies 2:1 interlace. 

Progressive. A video signal in which successive scan lines in each complete
  frame are vertically and temporally adjacent. Also called 1:1 Interlace,
  Sequential, Non-interlaced, Pro-scan. Examples of proposed progressive systems
  are 525/59.94/1:1 and 1250/25/1:1. 

Improved, Extended, Advanced, High-Definition Television Terms

IDTV, Improved Definition Television. A television system that offers picture
  quality substantially improved over conventional receivers, for signals
  originated in standard 525-line or 625-line format, by processing that
  involves the use of field store and/or frame store (memory) techniques at the
  receiver. One example is the use of field or frame memory to implement
  de-interlacing at the receiver in order to reduce inter-line twitter compared
  to that of an interlaced display. IDTV techniques are implemented entirely at
  the receiver and involve no change to picture origination equipment and no
  change to emission standards. 

EDTV, Extended [or Enhanced] Definition Television. A television system that
  offers picture quality substantially improved over conventional 525-line or
  625-line receivers, by employing techniques at the transmitter and at the
  receiver that are transparent to (and cause no visible quality degradation to)
  existing 525-line or 625-line receivers. One example of EDTV is the improved
  separation of  luminance and colour components by pre-combing the signals
  prior to transmission, using techniques that have been suggested by Faroudja,
  Central Dynamics and Dr William Glenn; these techniques reduce or eliminate
  NTSC artifacts such as dot crawl and hanging dots. Another example of EDTV is
  the use of progressive scanning at the camera, interlaced transmission and
  reconstruction of a progressive display at the receiver to reduce or eliminate
  interlace artifacts, as in the Faroudja SuperNTSC system. EDTV systems require
  changes in picture origination equipment, but are completely compliant with
  current emission regulations. 

Picture Aspect Ratio. The ratio of picture width to picture height. Usually
  abbreviated to Aspect Ratio. Current 525-line and 625-line scanning standards
  have a picture aspect ratio of exactly 4:3. HDTV is defined to have 16:9
  aspect ratio. 

Letter-box.  A television system that limits the recording or transmission of
  useful picture information to about three-quarters of the available vertical
  picture height of the distribution format (e.g. 525-line), in order to offer
  program material that has a wide picture aspect ratio. 

Wide-screen. A television system that offers a picture aspect ratio
  substantially wider than 4:3, using the full vertical picture area afforded by
  the distribution signal format (e.g. 525-line). Emission regulation changes
  are required for wide-screen terrestrial (UHF/VHF) TV transmission.
  Wide-screen may or may not be combined with EDTV; wide-screen is inherent in
  ATV and HDTV. 

ATV, Advanced Television. A system that distributes wide-screen television
  signals with resolution substantially improved over 525-line and 625-line
  systems. Terrestrial ATV broadcasting (VHF/UHF) would require substantial
  changes to current emission regulations. There is general acknowledgement that
  any ATV distribution system should offer at least stereo (two channel) audio,
  of CD quality. 

HDTV, High-Definition Television. A television system with approximately twice
  the horizontal and twice the vertical resolution of current 525-line and
  625-line systems, component colour coding (e.g. RGB or YCbCr), a picture
  aspect ratio of 16:9 and a frame rate of at least 24 Hz. 

Production, Exchange, Distribution Terms

HDTV Production. The original creation and editing of HDTV program material. 

SMPTE 240M. An HDTV production standard with 1125/60.00/2:1 scanning. 

HDTV Exchange. The interchange of HDTV program material among production,
  distribution and transmission organizations. Editing at the exchange stage is
  limited to insertion of segments such as commercials and lengthening or
  shortening the duration of program material up to 5 percent. 

ATV Distribution. The distribution of ATV program material to the ultimate
  viewing audience. Distribution may be by physical media such as videotape or
  videodisc; or by transmission (see below). 

ATV Transmission. The distribution of ATV program material to the ultimate
  viewing audience through RF media such as terrestrial VHF/UHF broadcasting,
  cable television (CATV) or direct broadcast satellite (DBS). 

ATV Transmission Terms

Channel-compatible ATV.  A system for transmitting ATV through VHF/UHF or CATV
  media whose RF spectrum assignment conforms to the six megahertz RF channels
  of current television transmission. According to FCC Docket 87-268,
  terrestrial VHF/UHF ATV transmission in the United States is constrained to be
  channel-compatible with 6 MHz channels. Channel-compatibility does not
  necessarily require single-channel transmission. 

Receiver-compatible ATV.  An ATV transmission system that provides ATV program
  material, possibly with reduced aspect ratio, to current 525-line or 625-line
  receivers. According to FCC Docket 87-268, ATV transmissions in the United
  States are constrained to be receiver-compatible. Receiver-compatibility can
  be obtained by augmentation-channel techniques or by simulcasting. 

Augmentation ATV.  An ATV transmission system that transmits an augmentation
  signal that is intimately associated with a main channel signal conformant to
  current broadcast standards. The two signals can be combined in an ATV
  receiver to recreate a complete ATV signal. Augmentation systems provide
  receiver-compatibility by default. No 625-line country is currently planning
  to use an augmentation channel approach for ATV. 

In-Band Augmentation ATV. An ATV transmission system that alters the 525-line
  or 625-line broadcasting standard by the addition of an augmentation signal
  within the RF channel bandwidth of the current standard. Such systems
  necessarily degrade reception of current signals. Sarnoff ACTV is an example
  of an in-band augmentation ATV system.  

Out-of-Band Augmentation ATV. A system that transmits an augmentation signal
  in an RF channel outside the main channel. The NYIT VISTA system is an example
  of an out-of-band augmentation system. 

Side Panels. In a wide-screen augmentation system, those portions of the width
  of a wide aspect ratio picture that are not conveyed in the 4:3 aspect ratio
  main channel. It is a technical challenge in an augmentation system to avoid
  visible seams between side panels and the main picture. 

Self-contained ATV.  A system that transmits a complete ATV signal in its own
  RF channel. A self-contained ATV system is channel-compatible if it transmits
  the ATV signal within a 6 MHz channel and receiver-compatible if it employs
  simulcasting. An example of a self-contained, non-channel-compatible system is
  NHK MUSE-9. Sometimes misleadingly called incompatible. 

Simulcast ATV. A system that transmits a self-contained ATV signal and
  achieves receiver-compatibility by simultaneously transmitting the same
  program material, possibly with reduced aspect ratio, in a separate 525/59.94
  or 625/50 channel. Zenith SC-HDTV is an example of such a system that in this
  case is optimized to exploit a currently-unused VHF/UHF taboo channel to
  convey the self-contained ATV signal. Sometimes confused with Incompatible
  ATV. 

Compatible ATV. An ATV transmission system that is intimately related in some
  manner to current broadcast. Although it is a self-contained ATV system,
  Zenith SC-HDTV is called compatible because of its use of a frame rate of
  59.94 Hz, its line rate of three times current 525/59.94 and the relationship
  of its RF channel utilization with NTSC. 

MUSE. A family of transmission standards for ATV that has been developed by
  NHK (Japanese Broadcasting Network). MUSE Hardware has been demonstrated for
  the 1125/60 system; other MUSE variants have been proposed. 

Digital HDTV Terms

CIF, Common Image Format.  The standardization of the structure of the samples
  that represent the picture information of a single frame in digital HDTV,
  independent of frame rate and sync/blanking structure. 

CDR, Common Data Rate. The standardization of a single data rate for digital
  HDTV, independent of the choice of image format, frame rate and sync/blanking
  structure. 

CFR, Common Frame Rate. The standardization of a single frame rate for digital
  HDTV. 

Sample Aspect Ratio.  The ratio of horizontal sample pitch to vertical sample
  pitch. A sample aspect ratio of unity achieves square pixels. 

"Square Pixels". A colloquial expression derived from computer graphics: a
  sample aspect ratio of precisely unity. 

Orthogonal Sampling.  Sampling a digital HDTV picture using samples placed on
  a regular two-dimensional spatial array or three-dimensional spatio-temporal
  array. 

Offset Sampling. Sampling a digital HDTV picture with an array of samples
  where alternate rows of samples are displaced by half of the pitch of the
  samples along that axis. Offset sampling may be applied to any combination of
  the horizontal/vertical/temporal sampling axes of a video signal. Also called
  Quincunx sampling. Offset sampling in the vertical/temporal plane is more
  commonly called interlace.

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