Now you can watch videos on YouTube in 720p High Definition (HD) quality for Free

YouTube recently launched an exclusive High Definition section for the US users. Users who have access to this section can watch the videos in 720p HD quality.



720p

720p refers to a progrssive HDTV signal with 720 horizontal lines and an Aspect Ratio (AR) of 16:9 (1.78:1). All major HDTV broadcasting standards include a 720p format which has a resolution of 1280x720, however there are other formats, including HDV and AVCHD for camcorders, which utilize 720p images with the standard HDTV resolution.

For HDTVs themselves 720p can also have different meanings. While you might expect a 720p HDTV to have a resolution of 1280x720, this isn't always the case. For many flat panel 720p HDTVs the actual native resolution is 1024x768. While these TVs accept 720 input signals (as do all HDTVs) they must downscale horizontally while slightly upscaling vertically to their native resolution, resulting in somewhat lower picture quality.

Advantages
Because it has fewer than half the number of pixels of the other standard HDTV picture format, 1080i, 720p can often include more accurate information for each pixel. This can result in more accurate approximations of the images displayed or higher framerates. While all HDTVs being manufactured today are capable of at least 60fps refresh rates, only 720p has matching profiles for actually encoding video. 720p displays are especially good for viewing most sports broadcasts, which generally originate in this format.

Disadvantages
For larger screens and new video sources 720p displays provide slightly lower quality than 1080p. Both Blu-ray and HD DVD use 1080p resolution for almost all encoding of the main feature on a disc.

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