Understanding high-resolution digital TV

Understanding high-resolution digital TV

Digital Television (DTV) is the transmission of pure digital
television signals, along with the reception and display of those
signals on a digital TV set. The digital signals might be
broadcast over the air or transmitted by a cable or satellite
system to our homes. However, when this technology comes to
Indonesia, we would need a decoder to receive the signals and use
it, in digital form, to directly drive our digital TV sets.

Digital TV relies on a compression called MPEG-2 to fit its
stunning images into a reasonable amount of bandwidth. In each
image, the MPEG-2 software records just enough of the picture so
that it does not look like something is missing. In subsequent
frames, the software only records changes to an image and leaves
the rest of the image. MPEG-2 reduces the data 55 to 1. MPEG-2 is
already the industry standard for DVD videos and some satellite
TV broadcast systems.

Compression reduces image quality from what is seen by the
digital camera in the studio. However, MPEG-2 eliminates image
detail that the human eye ignores anyway. The quality of the
image is very good, and significantly better than "TV babe gue"
(traditional analog TV).

The use of MPEG-2 permits a HDTV receiver to interact with
computer multimedia applications directly. For example, a HDTV
show could be recorded on a multimedia computer, and CD-ROM
applications could be played on HDTV systems. A digital TV
decodes the MPEG-2 signals and displays it just as a computer
monitor does, giving it high resolution and stability.

HDTV

High Definition Television, or HDTV, is a short high-
resolution digital television (DTV) combined with Dolby Digital
surround sound (AC-3). The idea for HDTV came from wide-screen
movies. Soon after wide-screen was introduced, movie producers
discovered that individuals seated in the first few rows enjoyed
a level of participation in the action not possible with
conventional movies. HDTV is the highest DTV resolution in the
new set of standards. This combination creates a stunning image
with stunning sound.

HDTV requires new production and transmission equipment at the
HDTV stations, as well as new equipment for reception by
consumers. The higher resolution picture is the main selling
point of HDTV. Imagine 720 or 1080 lines of resolution compared
to analog TV's 525 lines (in US) or 625 lines (in Europe and
Indonesia).

Six of eighteen DTV format are HDTV format. The formats used
in HDTV are 720p -- 1280x720 pixels progressive and 1080i --
1920x1080 pixels interlaced. Interlaced or progressive refers to
the scanning system. In an interlaced format, the screen shows
every odd line at one scan of the screen, and then follows that
up with the even lines in a second scan. Since there are 30
frames shown per second, the screen shows one half of the frame
every 1/60 of a second. For smaller screens this is less
noticeable. As screens get larger, the problem with interlacing
is flicker. Progressive scanning shows the whole picture, every
line in one showing, every 1/60 of a second. This provides for a
much smoother picture, but uses slightly more bandwidth.

One of them uses interlaced scanning and five of them use
progressive scanning. Of the remaining formats, eight are SDTV
(four wide-screen formats with 16:9 aspect ratios, and four
conventional formats with 4:3 aspect ratios), and the remaining
four are Video Graphics Array (VGA) formats. Stations are free to
choose which format to broadcast. Broadcasters would have to
squeeze the increased picture detail and higher quality surround
sound into the same 6-megahertz bandwidth used by analog
television

Following the introduction of HDTV in the film industry,
interest began to build in developing an HDTV system for
commercial broadcasting. Such a system would have roughly double
the number of vertical lines and horizontal lines when compared
to conventional systems. An important and critical consideration
is whether the new HDTV standard should be compatible with
existing color TV standards. When will this technology arrive in
Indonesia? Next year, probably. We will just have to wait ... and
wait for the provider. (Gatot)