DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

In 1993, the International Radio
Consultative Committee (CCIR) was
renamed ITU-R. 576i (or 625/50)
scanning is sometimes misleadingly
and incorrectly referred to as CCIR.
ITU-R (former CCIR)
International agreement is necessary to avoid contention
in the use of the electromagnetic (radio frequency,
RF) spectrum. The International Telecommunications
Union (ITU) is the body that achieves international
agreement on matters concerning RF spectrum. Its
ITU-R branch is responsible for setting television broadcast
standards. ITU-R agreements often result in de jure
(regulatory) standards in its member states; those
standards effectively have the force of law.
The ITU-R jurisdiction over radio transmission has, over
the years, extended into the domain of international
program exchange on videotape. Historically, videotape
recording standards have been intimately related to
studio signals; consequently, ITU-R is involved in studio
video standards. Its agreements in that domain are
called Recommendations in international standards
lingo; they amount to voluntary standards, comparable
to those of ISO or IEC.
The ITU-R also collects information from member states
about technical aspects of broadcasting. The ITU-R
publishes this information in Reports. ITU-R Reports are
not standards, although they are important guides to
implementors and users.
ITU-R scanning nomenclature
ITU-R notation for television transmission combines
scanning lines per frame and field rate with various
baseband video and RF transmission parameters, into
a system designated by a single letter such as B, G, H, or
M. ITU-R designations apply to the radiated signal;
there is no standard system of nomenclature for signals
at baseband, or signals on videotape or videodisc.
The ITU-R denotes a transmitted analog video signal by
its scanning system and bandwidth, denoted by a letter,
followed by a slash and its color-encoding method
(NTSC, PAL, or SECAM). Full specification of a color
video signal also requires the subcarrier frequency,
though this is usually implicit because only certain
combinations are in use. Informally, a color video signal
is denoted by the color-encoding method, followed by
572 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES