STANDARD DEFINTION TELEVISION

Standard definition Television in Australia follows the PAL (Phase Alternating Line) standard as opposed to the North American standard of NTSC (National Television System Committee).

In the PAL system, the picture is made up of 576 horizontal lines. Each one of those lines is comprised of 720 "picture elements" or Pixels, so a PAL standard TV frame is described as 720 x 576 in frame size. In fact, on a TV, it is not possible to see all these lines and about 10% of the picture is lost due to this anomaly called 'overscan'.

As an aside, this 'unseen' overscanned section of the picture is that part which lies outside the outer 'safe' zone guideline seen when the 'View Safe zone' option is turned on in your editing package.

In the older televisions, the ratio of the width to the height of the Display screen was set at 4:3. To get this ratio to work a standard was introduced that required the pixels be 'non-square' and so it came about that the ratio of the pixel width to height in standard definition 4:3 TVs was 1.06666.

By Frank McLeod

Dr Frank McLeod is a specialist physician who in his ‘day job' works in the area of Addiction Medicine. Frank reckons he ‘dribbled' into video as a way to get information across to his patients and their families in an accessible way that avoided information overload. From there, the monster just grew. With a long-time interest in things technical and gadgetry of all kinds, he had been writing tech review-type-articles on a casual basis for a medical publication for some time, when an introduction to David Hague led to his continuing this level of activity in the field of video.

Frank says that one of the parts he likes best about his involvement with Australasian Camcorder is the opportunity to play with other people's toys. The downside, he says, is having to give them back at the end of ‘playtime' that precedes publication of the resulting review.

"I suppose I want to present information from the non-professional point of view, which is not difficult, given that I am the only amateur punter in the camp," he says. With a strong commitment to the amateur video club movement, he is the Secretary of his local video club. In part because of this, and with a long time history as an avid DIY-er behind him, Frank has an interest in the do-it-yourself construction of devices for the amateur videographer and strongly wishes to continue this type of contribution as part of his future involvement with auscam

Comments(1):

1. Making Sense of TV Standards

   Frank, Just one matter in your article needs clarification. My understanding is that there is no PAL high definition standard. Similarly there is no NTSC high definition standard. The terms PAL and NTSC have no valid meaning in the High Definition world. Pal and NTSC refer specifically to analogue standard definition systems. Both European and American High Def systems use the same frame dimensions and the same colour space. The only difference is the 60hz (America) and 50Hz (Europe) frame refresh rates. Common usage may well be PAL and NTSC, but is technically wrong. The poor handling of colour by NTSC in Nth America is not the case with HD. May be best to use terms like 60HzHD and 50HzHD and leave terms like PAL and NTSC in the past where they belong. John Devenish

   Tuesday, March 30, 2010 John