About [HD]

HD (High-Definition) Videos

For high-definition video in broadcasting, see High-definition television. For other uses, see High-definition.

High-definition video is video of higher resolution than is standard. While there is no specific meaning for high-definition, generally any video image with more than 480 horizontal lines (North America) or 570 lines (Europe) is considered high-definition. 720 scan lines is generally the minimum even though many systems greatly exceed that. Images of standard resolution captured at rates faster than normal (60 frames/second North America, 50 fps Europe), by a high-speed camera may be considered high-definition in some contexts.
  

History

From a historical perspective, the first electronic scanning format 405 lines was the first "high definition" television system as the previous mechanical systems had far fewer scanning lines.
From 1939, the US and other European countries experimented with 441 lines and 605 lines until, in 1941, the Federal Communications Commission (FCC) mandated 525 lines for the US. In wartime France, René Barthélemy experimented with higher definitions, reaching 1015 and even 1042 lines. Official French transmissions finally began with 819 lines in late 1949; however, this standard was abandoned in 1984 upon the adoption of 625-line color on the TF1 network.

1980s

Modern HD specifications date to the early 1970s, when Japanese engineers developed the HighVision 1,125-line interlaced TV standard (also called MUSE) that ran at 60 frames per second. The Sony HDVS system was presented at an international meeting of television engineers in Algiers, April 1981 and Japan's NHK presented its analog HDTV system at a Swiss conference in 1983.

The NHK system was standardized in the United States as Society of Motion Picture and Television Engineers (SMPTE) standard #240M in the early 1990s, but abandoned later on when it was replaced by a DVB analog standard. HighVision video is still usable for HDTV video interchange, but there is almost no equipment around to perform this function. Attempts at shoehorning in HighVision into a 6 MHz broadcast channel were mostly unsuccessful. All attempts at using this format for terrestrial TV transmission were forsaken by the mid-1990s.
Europe developed HD-MAC (1,250 lines, 50 Hz), a member of the MAC family of hybrid analogue/digital video standards; however, it never took off as a terrestrial video transmission format. HD-MAC was never designated for video interchange except by the European Broadcasting Union.
The current high-definition video standards in North America were developed during the course of the advanced television process initiated by the Federal Communications Commission in 1987 at the request of American broadcasters. In essence, the end of the 1980s was a death knell for most analog high definition technologies that had developed up to that time.

1990s

The FCC process, led by the Advanced Television Systems Committee (ATSC) adopted a range of standards from interlaced 1,080-line video (a technical descendant of the original analog NHK 1125/30 Hz system) with a maximum frame rate of 60 Hz, and 720-line video, progressively scanned, with a maximum frame rate of 60 Hz.
In the end, however, the DVB standard of resolutions (1080, 720, 480) and respective frame rates (24, 25, 30) were adopted in conjunction with the Europeans that were also involved in the same standardization process. The FCC officially adopted the ATSC transmission standard (which included both HD and SD video standards) in 1996, with the first broadcasts on October 28, 1998.

2000s

In the early 2000s, it looked as if DVB would be the video standard far into the future. However, both Brazil and China have adopted alternative standards for high-definition video^{[HD Videos 4U]} that preclude the interoperability that was hoped for after decades of largely non-interoperable analog TV broadcasting.

Common High-Definition Video Modes

Video mode	Frame size in pixels (W×H)	Pixels per image1	Scanning type	Frame rate (Hz)
720p	1,280×720	921,600	Progressive	23.976, 24, 25, 29.97, 30, 50, 59.94, 60, 72
1080i	1,920×1,080	2,073,600	Interlaced	25 (50 fields/s), 29.97 (59.94 fields/s), 30 (60 fields/s)
1080p	1,920×1,080	2,073,600	Progressive	24 (23.976), 25, 30 (29.97), 50, 60 (59.94)

HD Content

High-definition image sources include terrestrial broadcast, direct broadcast satellite, digital cable, high definition disc (BD), digital cameras, internet downloads and the latest generation of video game consoles.

• Most computers are capable of HD or higher resolutions over VGA, DVI, and/or HDMI.

• The optical disc standard Blu-ray Disc can provide enough digital storage to store hours of HD video content. Digital Versatile Discs or DVDs (that hold 4.7 GB* for a Single layer or 8.5 GB* for a Double layer), look best on screens that are smaller than 36 inches (91 cm)^[HD], so they are not always up to the challenge of today's high-definition (HD) sets. Storing and playing HD movies requires a disc that holds more information, like a Blu-ray Disc (which hold 25 GB* in single layer form and 50 GB* for double layer) or High Definition Digital Versatile Discs HD-DVDs which hold 15 GB* or 30 GB* in single and double layer. * = Gigabyte = 1,073,641,324 bytes, 1,048,576 killabytes, or 1024 megabytes.

Blu-ray Discs were jointly developed by 9 initial partners including Sony, Phillips (which developed CDs),and Pioneer (which developed its own Laser-disc previously with some success) among others. HD-DVD discs were primarily developed by Toshiba and NEC with some backing from Microsoft, Warner Bros., Hewlett Packard, and others. On February 19, 2008 Toshiba announced it was abandoning the format and would discontinue development, marketing and manufacturing of HD-DVD players and drives.

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About [HD]

By: Azam Bilal on: 1:08 AM