Wednesday, April 2, 2008


1080p is the shorthand name for a category of display resolutions. The number "1080" represents 1,080 lines of vertical resolution,[1] while the letter p stands for progressive scan (meaning the image is not interlaced). 1080p is considered an HDTV video mode. The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal resolution of 1920 pixels. This creates a frame resolution of 1920×1080, or 2,073,600 pixels in total. The frame rate in Hertz can be either implied by the context or specified after the letter p, such as 1080p30, meaning 30 Hz.

1080p is sometimes referred to in marketing materials as "Full High-Definition". However, 2K/4K digital cinema technology is commercially available, and ultra-high definition video is in the research phase.

In addition to the meaning of 1080p as a display resolution, 1080p is also used to describe video equipment capabilities. Use of 1080p and the closely related 1080i labels in consumer products may refer to a range of capabilities. For example, video equipment that upscales to 1080p takes lower resolution material and reformats it for a higher resolution display. The image that results is different from the display of original 1080p source material on a native 1080p capable display. Similarly, equipment capable of displaying both 720p and 1080i may in fact not have the capability to display 1080p or 1080i material at full resolution. It is common for this material to be downscaled to the native capability of the equipment. The term "native 1080p capable" is sometimes used to refer to equipment capable of rendering 1080p fully.

Broadcasting standards

The ATSC and DVB support 1080p video, but only at the frame rates of 24, 25, and 30 frames per second (1080p24, 1080p25, 1080p30) and their 1000/1001-rate slow versions (e.g., 29.97 frames per second instead of 30). Higher frame rates, such as 1080p50 and 1080p60, could only be sent with more bandwidth or if a more advanced codec (such as H.264/MPEG-4 AVC) were used. Higher frame rates such as 1080p50 and 1080p60 are foreseen as the future broadcasting standard for production.[2]

In the United States, the ATSC is considering amending its standard to allow the incorporation of the newer codecs for optional usage like the DVB Project consortium already has done with DVB-S2.[3] However, doing so is not expected to result in widespread consumer availability of broadcast 1080p60 programming, since most of the existing digital television sets or external digital receivers in use in the United States would still only be capable of decoding the older, less-efficient MPEG-2 codec, while the bandwidth limitations do not allow for broadcasting two simultaneous streams on the same broadcast channel (e.g. both a 1080i MPEG-2 stream alongside a 1080p MPEG-4 stream).

Production standards

The movie industry has embraced 1080p24 as a mastering format in both native 24p form and in 24PsF form. This may be the first universal video standard which transcends continental boundaries, an area previously reserved for film.[4] Wrapping progressive video into the interlaced stream allows the video to maintain the progressive format, while minimizing bandwidth requirements using interlaced equipment.[5]

A new high-definition progressive scan format is not available for picture creation, but is currently being developed to operate at 1080p at 50 or 60 frames per second.[2][6] This format will require a whole new range of studio equipment including cameras, storage, edit and contribution links as it has doubled the data rate of current 50 or 60 fields interlaced 1920 × 1080 from 1.485 Gbit/s to nominally 3 Gbit/s. It is unable to be broadcast in a compressed transmission to legacy MPEG-2 based HD receivers. This format will improve final pictures because of the benefits of "oversampling" and removal of interlacing artifacts.



It's a common misconception that HDTV broadcasts cannot be in 1080p. In the United States, the ATSC standard allows 1080p24 and 1080p30 video. In practice, all major networks use a 60 Hz format in the MPEG-2 header -- either 720p60 or 1080i30. But that only dictates the formal output of the MPEG-2 decoding process, not the actual means of encoding the frames.

For material that originated from a 24 fps source (such as film), MPEG-2 allows the video to be coded as 1080p24, irrespective of the final output format. The progressively-coded frames are then tagged with metadata (literally, fields of the PICTURE header) instructing a decoder how to perform a 3:2 pulldown to interlace them. While the formal output of the MPEG-2 decoding process from such stations is 1080i30, the actual content is coded as 1080p24 and can be viewed as such. That is to say, twenty-four progressively-coded frames per second are present in the bitstream; it is the decoder that turns them into 60 interlaced fields per second. NBC is known to use this method with some stations.

Even for content that has not been encoded in this fashion, it is still usually possible to extract the original 24 source frames from a 1080i30 broadcast of 24 fps material, since no information is lost even when the broadcaster (as opposed to the receiver) performs the 3:2 pulldown

Internet content

There has been some content released in the 1080p format on the Internet. Some notable examples include the Apple QuickTime Trailers in the QuickTime HD 720p/1080p format, and the Microsoft WMV HD Content Showcase which offers clips in both 720p and 1080p formats. Another example of 1080p content is the MacBreak 1080p podcast created by Leo Laporte and Alex Lindsay. This podcast is distributed via the BitTorrent method of distribution because of the large file sizes resulting from the high bit-rates. BitTorrent also contains many 1080p movies which have been copied from Blu-ray Disc or Broadcast sources. Often the internet is the only source for many high definition movies.[citation needed] These are frequently in MKV/WMV format and are difficult for most computers to render smoothly. All 1080p content currently (as of March 2007) distributed on the Internet has frame rate of 24, 25, or 30 frames per second.

Consumer televisions and projectors

There is a growing selection of consumer televisions with support for both 1080p inputs and outputs. Several televisions in 2005 offered 1080p, including sets from JVC (using a technology called D-ILA which is a variation of LCoS), Hewlett-Packard, Mitsubishi, Sony, Panasonic, etc. The 2006 Consumer Electronics Show (CES) introduced 1080p displays from most manufacturers, available in various display technologies. The manufacturers of 1080p TFT LCD screens include Sharp and a few others in Asia. Also, 3:2 pulldown reversal (reverse telecine) for film-based 1080i60 signals is beginning to appear in some newer 1080p displays, which can produce a true 1080p quality image from film-based 1080i60 programs.

Computer monitors

Some modern widescreen liquid crystal display (LCD) monitors can natively display 1080p content. Widescreen WUXGA monitors for example support 1920×1200 resolution, which can display a pixel for pixel reproduction of the 1080p (1920×1080) format. The resolution is rare amongst laptops, but some laptops have a 15" or a 17" display that run 1920×1200. Additionally, many 23, 24 and 27 inch widescreen LCD displays use 1920×1200 as their native resolution. Other 1080p-compatible LCDs, on the other hand, have lower than 1920×1080 native resolution and cannot display 1080p pixel for pixel. The output is resized; and although it may not be noticeable to the viewer, what is seen is a slightly degraded version of the original image.

Cathode ray tube (CRT) computer monitors have long been capable of displaying (and exceeding) 1080p. However, since most CRT monitors have an aspect ratio of 4:3, one would either have to view the content stretched vertically or leave ¼ of the screen blank. Most CRT monitors will accept an input signal of 1920×1080 at 60 Hz, even if the specifications state that the maximum resolution is only 1024×768 at 85 Hz.[citation needed] This is because CRT circuitry only place a hard limit on the combination of vertical resolution and refresh rate, thus a lower refresh rate will allow a higher vertical resolution

Storage format

1080p-encoded titles have been released on HD DVD and Blu-Ray. Since the introduction of their first hardware generation, both players have been able to output 1080p video.[citation needed] Current players both allow output of film-based material in conventional interlaced 1080i30 form, and 1080p displays that are able to apply 3:2 pulldown reversal can deinterlace film-based content and achieve full 1080p image quality.

Video game consoles

Video game consoles such as Microsoft's Xbox 360 and Sony's PlayStation 3 are able to display 1080p through Component video and HDMI. Xbox 360 also supports 1080p on PC monitor or HDTV using the VGA input, the VGA HD AV cable allows the user to select specific computer resolution such as 1920x1200 and 1280x1024.

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