720p is a shorthand name for a high definition TV format. The number 720 stands for its 720 lines of horizontal resolution (or 720 pixels of vertical resolution if you prefer), and the letter p stands for progressive scan, or non-interlaced. When broadcast at 60 frames per second, 720p features the highest motion resolution possible under broadcast standards. Incidentally, movies shot on film—the kind you see at the theater—are only 24 frames per second, meaning that 720p has much smoother motion than movies!
Progressive scanning means you don’t have to worry about filtering out fine details to prevent flickering. Also, with progressive scan content, things like stripes in an image are unlikely to cause the moiré patterns that interlaced video is prone to. Interlaced is exactly what it sounds like—the horizontal lines fire in an alternating fashion, so that you never have a full frame, but rather two half-frames interlaced. Progressive scan is more like a movie, wherein an entire frame passes the screen, then another, then another, and so on.
720p is compatible with most flat panel TVs, like plasma and LCD TVs. These TVs must de-interlace images such as regular broadcast video and 1080i source material as they are inherently progressive scan. If you are using a CRT style TV, however, 720p must be converted to interlaced video before it hits your screen. Computer monitors are better able to handle progressive scan content as computers output exclusively progressive scan images, thus a computer CRT would be better equipped to play 720p content than a traditional CRT television.
Broadcast high definition is shown in either the 720p format or the 1080i standard. While the 1080i ostensibly has more lines of resolution, it is interlaced (Thus the i next to the number). This means you are looking at 540 line fields rather than a full frame. In effect, 720p is basically higher resolution than 1080i as a result of this interlacing. The scan lines on 1080i don’t translate directly into more resolution.
HD DVD players are capable of playing true 720p video. HD DVD players offer backward compatibility, enabling users to use a single player to play all types of HD DVD, DVD and CD. There is also a hybrid HD DVD format that contains both DVD and HD DVD versions of the same movie on a single disc. This format was intended to offer a smooth transition for the studios in terms of publishing movies, and to allow consumers with only DVD players to use the discs. DVD manufacturing companies can use their current equipment with only minor modifications when changing over to HD DVD.
HD DVD lost the high definition format war with Sony’s Blu-Ray format. As a result the cost of the HD DVD disks has fallen from $40 in some cases to as little as $10.Payers can be bought for less than $60, compared with about $250 for a Blu-Ray player. Thousands of HD DVD titles are still available, including some recent hits like American Gangster.
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