Advantages of HDTV expressed in technical terms

Plus, high-definition television (HDTV) yields a better-quality image than does standard television, because it has a greater number of lines of resolution. Because the signal is of a digital nature, it produces neither a snowy nor pale image from a weak signal or signal interference effects, such as herringbone patterns, or vertical rolling. Image colours are more realistic, because of the greater bandwidth. The visual information is some 2-5 times sharper because the gaps between the scan lines are narrower or invisible to the naked eye. Television content photographed and preserved on 35 mm film can be viewed at nearly its original resolution.

The lower-case "i" appended to the numbers denotes interlaced; the lower-case "p" denotes progressive. The interlaced scanning method, the 1,080 lines of resolution are divided into two, the first 540 lines are painted on a frame, the second 540 lines are painted on a second frame, reducing the bandwidth. The progressive scanning method simultaneously displays all 1,080 lines of resolution at 60 frames per second, on a greater bandwidth. (See: An explanation of HDTV numbers and laymen's glossary)

Often, the broadcast HDTV video signal soundtrack is Dolby Digital 5.1 surround sound, enabling full, surround sound capabilities, while STBC television signals include either monophonic or stereophonic audio, or both. Stereophonic broadcasts can be encoded with Dolby Surround audio signal. Brasil opted to upgrade the ISDB-T Japanese standard to H.264 AVC Mpeg4 part 10 in the video compression and HE-AAC for audio compression because Dolby is not open and the royalty fees are more expensive that of Mpeg4 H.264 AVC and renamed the upgraded standard to ISDB-Tb that now became the International ISDB-T standard.

http://en.wikipedia.org/wiki/High-definition_television