What is High Definition Television?
High-definition television (HDTV) has a higher resolution than conventional television (known as standard-definition TV, or SDTV). HDTV is a digitally broadcast system and consequently uses less bandwidth than traditional analogue systems. The less the bandwidth then the easier and almost certainly faster it is to deliver the data or picture to your TV set. There have been several predecessors to the now current HDTV and any concept of high definition is relative to existing systems. The system we now have was in fact first broadcast publicly in 1997 by CBS in the USA. The HDTV we have implemented today is based on the ATSC HDTV standards (the American Advanced Television Systems Committee) for North America and the DVB HDTV for South America, Africa, Europe and parts of Asia.
The key factors which define the bandwidth and hence the eventual quality of a digital picture is:-
1. The number of pixels on a screen. There are many technical issues defining the standards but in layman’s terms there are really 2 HDTV resolutions and they are 1280 x 720 (just under 1 million pixels) or 1920 x 1080 (just over 2 million pixels). The bigger your screen then the more likely that you’ll have the 2 mega-pixel resolution.
2. The number of frames per second to be displayed. Again there are different technologies providing different definitions but put simply HDTV frame rates are 25 frames per second or 30 frames per second.
3. The data compression or video compression algorithms used are now the Mpeg-2 and Mpeg-4 standards. There are common standards for the compression (and subsequent reverse of the compression) which can be accommodated on some chip or small card. Compression simply means that there are some clever formulae which remove the necessity to store each pixel for each frame. If for example we record the changes from one frame to another then we’d have some form of compression.
Did you enjoy this post? Why not leave a comment below and continue the conversation, or subscribe to my feed and get articles like this delivered automatically to your feed reader.
Comments
No comments yet.
Sorry, the comment form is closed at this time.