Ulead MEDIASTUDIO PRO 6.0, Руководство пользователя

Страница: 338 / 360

MEDIASTUDIO PRO USER GUIDE 338
The world of analog video
Video, in general, starts out as a series of electrical signals (analog waves)
which have been recorded by a camera and then broadcast over airwaves
or played back from a video tape. To be able to see and hear the video
information contained within this signal, it has to follow certain standards
and be decoded by a specific device. The most common device is a
television set and the most common standards are NTSC (National Televi-
sion Standards Committee) and PAL (Phase Alternating Line). NTSC is
predominant in North America and many Asian countries, while most of
Europe and the South Pacific follow the PAL standard. These different
standards explain why you cannot view video recorded in England on a
television set in the United States and vice versa, without special equip-
ment.
Inside the video signal
The standard video signal defines color by two factors: luminance and
chrominance. Luminance is the black and white values of color and serve
to control the brightness and contrast of the picture, whereas chrominance
is the colors of the video itself and control the hue and saturation of the
picture. The NTSC and PAL standards both utilize luminance and chromi-
nance and merge them into the one signal along with any audio informa-
tion. This type of signal is called composite video as it combines the
various aspects of video. Another type of signal, component, separates the
luminance and chrominance values of a video signal and offers better
quality through greater control over the various aspects of color. A good
example of component video is Betacam.