In 1983, the International Telecommunication Union’s radiotelecommunications sector (ITU-R) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. This WP considered many views and through the 1980s served to encourage development in a number of video digital processing areas such as conversion between 30/60 and 25/50 picture rates using motion vectors that led to other outcomes. While a single standard was never finalized, a common aspect ratio of 16:9 was agreed to at the first meeting at the BBC’s R & D establishment at Kingswood Warren. Initially the Japanese 5:3 ratio was considered but a proposal to widen it to 5 1/3:3 = 16:9 was accepted. The resulting ITU-R Recommendation ITU-R BT.709-2 (”Rec. 709″) includes the 16:9 aspect ratio, specified colorimetry, and 1080i (1,080 actively-interlaced lines of resolution) and 1080p (1,080 progressively-scanned lines) scanning modes. It also includes the 1440 x 1152 HDMAC scanning format. 720p formats were strongly resisted by some ITU-R members[citation needed] and were not standardized there. Both 1920×1080 and 1280×720p (720 progressively-scanned lines) systems for a range of frame and field rates are also defined by several SMPTE standards.
However, the standardization of HDTV did not lead to its adoption. Early HDTV commercial experiments such as NHK’s MUSE required over four times the bandwidth of a standard definition broadcast, and despite the effort made to shrink the required bandwidth into about 2 times of that of the SDTV’s, it still was distributable only by satellite. In addition, recording and reproducing an HDTV signal was also a technical challenge in the early years of HDTV. Nevertheless, the first HDTV sets went on sale in the United States in 1998.
Japan is the only country with successful commercial analog HDTV, known as “Hi-vision”, featuring a 5:3 aspect ratio screen with 1,125 interlaced lines (1,035 active lines) at the rate of 60 fields per second. Elsewhere, in Europe, analog 1,125-line HD-MAC television failed in its test broadcasts in the early 1990s.
However, it was not until the early 2000’s that storage means of enough capacity and computer processing power for dense compression algorithms made commercial applications of HDTV affordable for consumers and profitable for TV channels or the video rental industry.
HDTV became viable due to the transition from analog to digital TV broadcasting. Digital compression methods such as MPEG-2 and MPEG-4 allow the bandwidth of a single TV channel (in the US, 6 MHz) to carry up to 5 TV programs of standard definition or up to 2 channels of high definition.
Current HDTV broadcast standards include ATSC (US) and DVB (Europe). HDTV can also provide 5.1-channel surround sound audio using e.g. the Dolby Digital (AC-3) format.
Sorce = wikipedia