Xref: utzoo comp.graphics:6807 rec.video:7476 sci.electronics:7373
Path: utzoo!attcan!uunet!cs.utexas.edu!sun-barr!newstop!sun!vector!poynton
From: poynton@vector.Sun.COM (Charles A. Poynton)
Newsgroups: comp.graphics,rec.video,sci.electronics
Subject: HDTV and ATV Glossary (TN32)
Summary: High Definition Television and Advanced Television Glossary
Keywords: 525/59.94, 625/50, NTSC, PAL, SECAM, Component, Composite, 
	  S-video, MAC, Interlace, Progressive, IDTV, EDTV, 
	  Picture Aspect Ratio, Letter-box, Wide-screen, ATV, HDTV, 
	  Production, Exchange, Distribution, Transmission, 
	  Channel-compatible, Re
Message-ID: <120919@sun.Eng.Sun.COM>
Date: 11 Aug 89 05:54:38 GMT
Sender: news@sun.Eng.Sun.COM
Lines: 257

Here's a contribution that may unravel some of the confusion surrounding
HDTV, ATV. IDTV, EDTV, and so on.  The most important point is that HDTV
relates to production and exchange of programs, and has immediate
relevance to computer graphics.  Advanced television (ATV) concerns the
delivery of entertainment programming to consumers, and has very little to
do with computing.

To me it is ludicrous to suggest that is strategically important for the
U.S. to resurrect domestic colour television receiver manufacturing.  Even
more ridiculous is the suggestion (by George Gilder in Fortune) that the
U.S. can, in a year or two, leapfrog current [Japanese] HDTV technology.

Let's get on with exploiting HDTV technology in computing, where we've
ALREADY got a vital and profitable industry!  (Or should I say, WHILE
we've still got it?)

The preceeding was my opinion.  What follows is fact.

C.

p.s.  1250/24, 2048-by-1152, 74.25 MHz.  Dare to be square!

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Charles A. Poynton			Sun Microsystems Inc.
			2550 Garcia Avenue, MS 8-04
415-336-7846				Mountain View, CA 94043

"Japan has no laws against damage to its flag, but it has strict laws
forbidding the burning of foreign flags lest this give offense to the
country in question." -- The Economist, July 1, 1989, p. 19.
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High Definition Television (HDTV) and Advanced Television (ATV) Glossary

Charles A. Poynton, Sun Microsystems, Inc.         TN32  89/08/07  18:26


525-LINE, 625-LINE  TELEVISION TERMS

525/59.94/2:1.  A raster scanning standard used primarily in North 
America and Japan, having 525 total lines (of which approximately 483 
contain picture information), a field rate of 59.94 Hz, and interlace.  
Without the "/2:1" notation, interlace is implicit.  Colour in 525/59.94 
systems is commonly encoded using the NTSC method.  Often colloquially 
referred to as 525/60, and often incorrectly denoted NTSC.

625/50/2:1.  A raster scanning standard used primarily in Europe and 
Asia, having 625 total lines (of which 575 contain picture information), 
a field rate of 50 Hz, and interlace.  Without the "/2:1" notation, 
interlace is implicit.  Colour in 625/50 systems is usually encoded 
using the PAL method (although France, the USSR, and certain other 
countries use SECAM).  Often incorrectly denoted PAL or SECAM.  

NTSC,  National Television Systems Committee.  (1) The group which in 
1953 established 525-line, 2:1 interlaced, 59.94 Hz field rate, 
composite colour television signals in the U.S.  More properly referred 
to as NTSC-II.  [The original NTSC, now properly referred to as NTSC-I, 
established 525-line, 2:1 interlaced, 60.00 Hz field rate monochrome 
television in the U.S. in 1943.]  (2) A method of composite colour 
encoding based on quadrature modulation of U and V colour difference 
signals onto a colour subcarrier.  Used only in 525/59.94 systems, with 
a subcarrier frequency of about 3.579455 MHz.  

PAL, Phase Alternate Line.  A method of composite colour encoding 
similar to NTSC, except that the phase of the V-axis colour difference 
signal inverts at the horizontal line rate.  Commonly used in 625/50 
systems with a subcarrier frequency of about 4.433618 MHz, but also used 
with a subcarrier of about 3.579455 MHz in the PAL-N system (e.g. 
Argentina), and with 525/59.94 scanning and a subcarrier frequency of 
about 3.575611 MHz in the PAL-M system (e.g. Brazil).  

SECAM, Sequential Couleur avec Memoire.  A method of composite colour 
encoding using line-alternate U and V colour difference signals, 
frequency modulated onto a subcarrier.  Used only in 625/50 systems 
(e.g. France, USSR).  

Component.  A video system which conveys colour using three separate
signals.  Examples are RGB, YUV, MAC.

Composite.  A video system which uses the spectral interleaving (or 
frequency interleaving) technique to encode (combine) luminance and 
colour information into a single signal.  Examples are NTSC, PAL, SECAM.  

S-video, S-connector, YC3.58, YC4.43.  An interface which conveys 
luminance, and quadrature modulated chrominance, as two separate signals 
on a specific 4-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 completely separable.  

MAC, Multiplexed Analog Component.  A video system which transmits three 
colour components, usually YUV, in time-compressed serial analog form.  

Interlace.  A video signal in which alternate raster lines of a frame 
are separated into two fields displaced in time by half the frame time. 
Also called 2:1 Interlace.  Examples are 525/59.94/2:1, 625/50/2:1, 
1125/60.00/2:1.  

Progressive.  A video signal in which all scan lines of a complete frame 
are closely related in time.  Also called 1:1 Interlace, Sequential, 
Non-interlaced, Pro-scan.  Examples are 525/59.94/1:1, 1250/24/1:1.  

IMPROVED, EXTENDED, ADVANCED, HIGH DEFINITION TELEVISION TERMS

IDTV, Improved Definition Television.  A television system which offers 
picture quality substantially improved over conventional receivers, for 
signals originated in standard 525-line or 625-line format, by 
processing which 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, 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 Definition Television.  A television system which offers 
picture quality substantially improved over conventional 525-line or 
625-line receivers, by employing techniques at the transmitter and at 
the receiver which are transparent to (and cause no visible quality 
degradation to) existing 525-line or 625-line receivers.  Examples are 
improved luminance/colour separation made possible by pre-combing the 
transmitted signals such as has been suggested by Faroudja, Central 
Dynamics, and Dr William Glenn, in order to reduce or eliminate NTSC 
artifacts such as dot crawl and hanging dots.  Another example 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 
systems both have a picture aspect ratio of 4:3.  

Letter-box.   A television system which 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 which has a wide aspect 
ratio.  

Wide-screen.  A television system which 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 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 which 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 system which has approximately 
twice the horizontal and vertical resolution of current 525-line and 
625-line television, a frame rate of at least 24 Hz, component colour 
coding (e.g. RGB or YUV), and a picture aspect ratio of 16:9.  

PRODUCTION, EXCHANGE, DISTRIBUTION TERMS

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

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%.  

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 which has carrier-frequency assignments conformant to 
current 525-line or 625-line television transmission.  According to FCC 
Docket 87-268, terrestrial VHF/UHF ATV transmissions in the U.S. are 
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 which 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 U.S.  are constrained to be receiver-compatible. 
Receiver-compatibility can be accomplished by single-channel ATV, 
augmentation-channel ATV, or simulcasting.  

Single-channel ATV.  An ATV transmission system which alters the 
525-line or 625-line broadcasting standard by the addition of 
augmentation signals within the channel bandwidth of the current 
standard.  Such systems may degrade reception of current signals.  
Sarnoff ACTV-I is an example of a single-channel ATV system.  

Augmentation-channel ATV.  An ATV transmission system which transmits an 
augmentation signal associated with a main channel 525/59.94 or 625/50 
signal, in order that signals from both channels can be combined in an 
ATV receiver to form an ATV signal.  Augmentation-channel systems 
provide receiver-compatibility by default.  Augmentation channels of 
3 MHz and 6 MHz have been proposed for the U.S.  Examples of 
augmentation-channel ATV systems are N.A. Philips HDS-NA, and NYIT 
VISTA.  Sarnoff ACTV-II is an example of a hybrid single-
channel/augmentation-channel system, because it transmits augmentation 
information in both the main NTSC channel and a separate augmentation 
channel.  

Simulcast ATV. A system which transmits a complete ATV signal within an 
RF channel of the same bandwidth as current 525-line or 625-line 
broadcasts, and which achieves receiver-compatibility through simulcast 
of the same program material, possibly with reduced aspect ratio, in a 
separate standard channel.  Zenith SC-TV is an example of such a system, 
which in this case is optimized to exploit a currently-unused VHF/UHF 
taboo channel to convey an entire ATV signal.  Sometimes confused with 
Incompatible ATV.  

Incompatible ATV.  A system which transmits a complete ATV signal in a 
format not intimately related to existing broadcast standards.  An 
example of an incompatible system is NHK MUSE-9.  An incompatible ATV 
system is channel-compatible if it transmits the ATV signal within a 
6 MHz channel. An incompatible ATV system is receiver-compatible if it 
employs simulcast of the same program material, possibly with reduced 
aspect ratio, in a separate NTSC channel.  

DIGITAL HDTV TERMS

CIF, Common Image Format.  The standardization of the structure of the 
samples which represent picture information 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, applicable to two or more different frame rates.

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.  

Orthogonal sampling.  Sampling a digital HDTV picture with an array of 
samples placed on a regular two-dimensional 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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