It was first standard definition or SDTV. This system has a vertical resolution of 480 lines and uses an interlaced signal. An interlaced signal means that the signal draws frames, one pass for the even vertical lines and another pass for the odd lines. Enhanced definition TV (EDTV) came out next which uses software interpolation in its video distribution system. It delivers a more progressive scanning than SDTV. Progressive scanning emits smoother and better resolution than the interlaced signal produced in SDTV. It is especially good for programs which have fast and more movements like sports shows.



Then the HDTV video distribution system boomed. High-definition television or HDTV distribution is a broadcasting system with a higher image resolution than the SDTV or EDTV. It uses highly efficient modulation techniques and requires a much lower bandwidth in its digital broadcasting as long as the video compression is sufficient. It also reduced the use of antenna and receiver hardware requirements. With HDTV distribution, better image quality is projected since gaps are now invisible to the naked eye. Video distribution system of an HDTV is similar to a theater with its full 5.1 surround sound audio quality capabilities supported by Dolby Digital.

HDTV Distribution: 720p, 1080p or 1080i?

As defined by the Advanced Television Systems Committee, the standards used in an HDTV distribution are originally of 18 different standards, however, not all of these standards are used. The usual standards for an HDTV video distribution system are 720p, 1080p or 1080i. The letters correspond to the display technique being used. The letter ?p? stand for progressive scan while the letter ?i? means interlaced. The number before those letters represents the lines of resolution displayed in the television. It usually has a wide screen display, width to height ratio of 16:9. It is said that the higher the number, the better. But a 1080p is said to be the best choice for an HDTV distribution since it displays more picture information in a much better progressive format than the higher resolution 1080i.

There are three major parameters of an HDTV video distribution system. They are:

1.Frame Size

2.Framing Rate

3.Scanning System

Whatever video distribution system your television has, it is still significantly limited by the picture quality the source signal transmits to your television. This means that a 720p from ESPN, FOX, or ABC Channel will not come out improved picture quality even in your 1080p television. Television networks that broadcast 1080i are CBS and NBC. This will result to a sharper image projected in 1080i or 1080p HDTV. The difference is more visible and detailed when shown on television sets with larger screens.

For an HDTV distribution, a special chip scales the signal of a system that is lower than a 1080i or 1080p. It will interpolate to emit a much better picture quality and combine the odd and even frames to show its maximum distribution of 1080p. Hence, it will result to an optimum performance like that of a 1080p video.