The Difference between EDTV and HDTV

by Kenny Hemphill

Confused by EDTV vs HDTV? We don't blame you. The number of acronyms floating about with regard to digital TV is frightening. What's even more worrying is that very often they are used by people who have little or no knowledge about what they mean. If the person selling you doesn't know the difference between EDTV vs HDTV, how are customers supposed to decide which TV or projector to go for? In our guide below, we've tried to distill the technical info into as few words as possible and make it as straightforward to understand as we can. To properly explain EDTV vs HDTV, we need to step back a bit. Traditional TV has 525 lines of video which are interlaced. Interlacing just means that every frame of video is split into two fields and each field is shown alternately. Although there are 525 lines in the signal, only 480 lines contain video, so it is sometimes referred to as 480i (480 lines interlaced). This is known as Standard Definition TV, or SDTV. While this has worked well enough for fifty years, as TV sets have got bigger and projectors more popular, the quality deficiencies have become increasingly apparent. The ultimate answer to improving the quality of the image displayed on your TV is HDTV, however, as a step on the road to HDTV, the industry came up with Enhanced Definition TV, or EDTV. This system contains the same 480 lines as SDTV, but they are progressive scan. Hence EDTV is also known as 480p. Progressive scanning just means that instead of splitting the signal into two fields and showing half the lines at a time, all 480 lines of video are shown at once. This results in a noticeable improvement in the quality of video. The bad news in relation to EDTV vs HDTV is that you need a completely new TV or projector to display both EDTV and HDTV. Most DVD players on the market today are progressive scan, meaning they output EDTV signals, however, in order to view the progressive scan picture in all its glory, you need a TV or projector capable of displaying it and that, unfortunately, means getting a new TV. In terms of content, there is very limited TV content available in HDTV format, and there is still wrangling about the standard for HD DVDs. However, every DVD disc on the market can be displayed in EDTV right now. Bottom line? Pretty much every HDTV projector or TV on the market today will display EDTV as well. So while there may not seem like a great deal of point in getting a new display for the limited HDTV content that is available today, it is worth it to watch your DVD collection in EDTV, the difference between SDTV and EDTV really is that big. About the Author Kenny Hemphill is the editor and publisher of The HDTV Tuner