Analog Television Video Formats - Ntsc, Pal And Secam - Creative Sound Blaster Audigy 2 ZS User Manual

Analog Television
Video Formats –
NTSC, PAL and
SECAM
The television standards define a video signal that is broadcast serially as a set of
horizontal scan lines with a varying brightness (luma) and color (chroma;
originally not present in the black-and-white days). There are one luma signal and
two chroma signals. The scan lines are reproduced on a television screen in fields –
th
every 60 of a second (for NTSC), half the entire image is displayed, then the
other half is displayed in the next 60
frame, which is thus displayed every 30
interlaced, since the even scan lines are displayed, then the odd scan lines. Since
the luma and chroma components are integrated into one signal, it is also
described as a composite video signal. The ratio of horizontal dimension to vertical
dimension of the frame, or aspect ratio, is 4x3, corresponding to the physical
dimensions of a television screen. Film content in contrast is projected on much
wider theater screens; in its digital form it has an aspect ratio called 16x9 or
widescreen.
NTSC
The television video system used in North America and certain Asian countries.
Uses 30 frames per second (29.97) and has 525 scan lines. The higher frame rate
reduces flicker.
PAL
The television video system used in Europe and parts of Asia. Uses 50 frames per
second, with 625 scan lines.
SECAM
The television video system used in France, eastern Europe and Africa. Like PAL,
uses 50 frames per second, with 625 scan lines.
Film video
24 frames per second; doesn't have scan lines since it is captured historically to
celluloid film just as in a conventional camera (a "motion picture"), for projection,
not broadcast. The frames are not split into fields (thus it is called progressive, not
interlaced, video). Employs an aspect ratio called widescreen or 16x9 in its digital
form.
th
of a second. These two fields make up a
th
of a second. The TV signal is said to be
Technology Glossary A-4