HDTV Formats Explained

There are a few varieties of HDTV formats currently in use today. All are considerably better in image quality that conventional Standard Definition television or SDTV -- therefore the High Definition moniker. However not all HDTV formats are created equal. In this section of the Home Theater Systems FAQ the differences in standard definition and high definition formats are explained in progressive order of image quality.


The standard NTSC television broadcast format which has been in use since the early days of television broadcasting. It is an archaic format compared to modern standards but still serves the viewing public quite well out of necessity. In 525i there are actually only 480 lines of usable picture information available. The remaining lines are used for synchronization pulses. The "i" designation refers to "interlaced" scan format wherein alternating lines of the image are created from top to bottom of the screen. First the odd numbered lines are drawn and then the even numbered lines are created. The 525i format is prone to "jaggies" on straight line images which is an undesirable artifact of NTSC.


Most standard DVD players currently on the market are capable of 480p playback through the RGB video connections. 480p is considered EDTV or "extended definition" television. The "p" designation refers to progressive scan wherein the image is drawn progressively from top to bottom of the screen. The image quality is superior to 525/480i and is much more smooth and film-like in quality. 480p is only usable on TVs with RGB inputs which include EDTV and HDTV sets.


Much better image quality is offered by the 720p format. This is due to almost twice the lines of resolution over 480p. Again the image is drawn from top to bottom progressively. 720p is utilized by many "upscaling" DVD players to increase the image quality of standard DVD players and is also utilized by FOX and ABC on their HD broadcasts.


Again by greatly increasing the available lines of resolution - 1080i is an improvement over 480p but is marginal over 720p due to the interlaced image production. In fact many videophiles prefer 720p over 1080i. 1080i is utilized by NBC and CBS for their HD programming.


The best HDTV format, 1080p offers the most lines of resolution drawn progressively on the screen. Unfortunately the only 1080p sources are currently available via HD-DVD and Blu-ray discs. If your budget can handle it there is no better image available than a Blu-ray disc on a 1080p HD video display.

HDTV Formats

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