High-definition television

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High-definition television (HDTV) is a new television broadcasting system which uses a higher resolution than a normal television. With HDTV, people can watch television in higher quality than old television, giving a more vivid and clear screen.

Most HDTV systems use digital signals with a 16:9 aspect ratio (width to height). This is different to SDTV (standard-definition television) which uses analog signals and a 4:3 aspect ratio.

HDTV picture resolution is at least twice that of SDTV, so it can present a more vivid screen than analog television or DVD. HDTV can control resolution efficiently.

Some videos on the website YouTube, a free video sharing website that lets people upload and view videos, are in HD.

There are different standards. Common ones are:

  • 1920x1080, progressive scan, requiring about 2,07 MPixels per frame. This is known as 1080p.
  • 1920x1080, interlaced, 1.04 MPixel per field. This is known as 1080i.
  • 1280×720, progressive, 0.92 MPixel per frame. This is known as 720p.

As a comparison, PAL plus is at 1024x576 pixels, and NTSC at 853x480 pixels.

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