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)