HDTV Resolutions: 480p - 720p - 1080i - 1080p

Reprinted from Wikipedia

480p is the shorthand name for a video mode. The p stands for progressive scan, i.e. non-interlaced, while the 480 denotes a vertical resolution of 480 lines, usually with a horizontal resolution of 854 pixels and a 16:9 aspect ratio on high-definition television (HDTV), or 640 pixels and 4:3 aspect ratio on standard-definition television (SDTV). The frame rate is usually 30 or 60 hertz and can be given explicitly after the letter. 480p is more common in countries that use or have used the interlaced NTSC system like North America and Japan. With doubled temporal resolution, 480p60 is considered enhanced-definition television (EDTV). It can be transported by both major digital television formats, ATSC and DVB.

720p

Reprinted from Wikipedia

720p is the shorthand name for a category of HDTV video modes. The number 720 stands for 720 lines of vertical display resolution, while the letter p stands for progressive scan or non-interlaced. When broadcast at 60 frames per second, 720p features the highest temporal (motion) resolution possible under the ATSC standard. Progressive scanning reduces the need to prevent flicker by filtering out fine details, so spacial (sharpness) resolution is much closer to 1080i than the number of scan lines would suggest.

Specifications

720p assumes a widescreen aspect ratio of 16:9, and a horizontal resolution of 1280 pixels for a total of about 0.92 million pixels. The frame rate (in this case equal to the field rate) can be either implied by the context or specified in hertz after the letter p. The five 720p frame rates in common use are 24, 25, 30, 50 and 60 Hz (or fps). In general, traditional PAL and SECAM countries (Europe, Australia, much of Asia, Africa, and parts of South America) are or will be using the 25p and 50p frame or field rates, whereas traditional NTSC countries (North and Central America, Japan, South Korea, Philippines ) are using 24p (for movies), and 60p for high motion programming. All variants can be transported by both major digital television formats, ATSC and DVB.

720p is directly compatible with newer flat panel technology such as plasma and LCD which are inherently progressive and must perform deinterlacing to display 1080i source material. 720p must be scan converted for display on most CRT-based consumer televisions which are generally interlaced-only display devices.[1] However, CRTs intended for use as computer monitors are progressive-only devices that can be run at 1280×720p60 either natively or through a refresh rate tweaking utility.

720p versus 1080i

Some United States broadcasters use 720p60 as their primary high-definition format; others use the 1080i standard. While 720p presents a complete 720 line frame to the viewer between 24 to 60 times each second (depending on the format), 1080i presents the picture as 50 or 60 partial 540 line "fields" (24 complete 1080-line fields, or "24p" is included in the ATSC standard though) which the human eye or a deinterlacer built into the display device must visually and temporally combine to build a 1080 line picture. The main tradeoff between the two is that 1080i may show more detail than 720p for a stationary shot of a subject at the expense of introducing interlace artifacts from a motion of the camera (such as a pan) or motion of the subject. 720p is used by ABC and ESPN because the smoother image is desirable for fast-action sports telecasts. Fox Broadcasting Company uses the tagline "the nation's finest high-definition standard" in advertising its 720p programming.

The European Broadcasting Union (EBU) recommends to its members to use 720p50 for emission with the possibility of 1080i50 on a programme-by-programme choice and 1080p50 as a future option[1][2]. The BBC is one of the only members so far transmitting in HDTV. All commercial European HDTV services so far use 1080i50.

References

1. ^ EBU Technical Recommendation R112 - 2004
2. ^ http://www.ebu.ch/en/technical/trev/trev_home.html
3. HD standards in use.

1080i

Reprinted from Wikipedia

1080i is the shorthand name for a category of video modes. The number 1080 stands for 1080 lines of vertical resolution, while the letter i stands for interlaced or non-progressive scan. 1080i is considered to be an HDTV video mode. The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal resolution of 1920 pixels and a frame resolution of 1920 × 1080 or about 2.07 million pixels, and a field resolution of 1920 × 1080 / 2 (because it's interlaced) or about 1.04 million pixels. The field rate (not the frame rate) in hertz can be either implied by the context or specified after the letter i. The two field rates in common use are 50 and 60 Hz, with the former (1080i50) generally being used in traditional PAL and SECAM countries (Europe, Australia, much of Asia, Africa), the latter (1080i60) in traditional NTSC countries (e.g. United States, Canada and Japan). Both variants can be transported by both major digital television formats, ATSC and DVB.

Some people prefer to use the line number of fields, which is half that of frames, in their nomenclature and thus call this mode 540i, likewise 240i and 288i. Others, including the European Broadcasting Union (EBU), prefer to use the frame rate instead of the field rate and separate it with a solidus from the resolution as in 1080i/30 and 1080i/25, likewise 480i/30 and 576i/25.

1080i is directly compatible with numerous CRT-based HDTV sets. 1080i is compatible with newer 720p- and 1080p-based televisions but must be deinterlaced first in order to be displayed on those sets.

Due to a curiosity of the NTSC format, the field rate of actual 1080i broadcasts is usually 0.1% slower than is implied. For example, a 1080i60 or "60 Hz" transmission actually displays about 59.94 fields each second. Both the straight 24/30/60 and 23.976/29.97/59.94 frequencies are supported by current standards.

1080i vs 1080p

The progressive-scan versions of the 1080-line resolution is known as 1080p. Current digital television broadcast systems and standards are not equipped for 1080p50/60 transmission. Also, the majority of consumer televisions offered for sale are currently not equipped to receive or decode a 1080p signal at any frequency. It is less bandwidth-intensive to broadcast a movie at 1080p24 than 1080i60, since 20% less data would be transferred. In addition, when the source material is 24 frames per second, as are most films, it would be easy to convert a 1080p24 broadcast to an NTSC 1080i60 format using a 3:2 pulldown process (see telecine). Moreover, displaying a p24 broadcast on an i50 system (such as PAL) requires the speed of video and audio be increased by over 4% (to 25 frames per second).

Therefore a hybrid is often used for movies and the like: the frames (25 or 30 per second) are segmented into two interlaced fields with equal time index (psf, progressive in or with segmented frames). The deinterlacer has to perform a simple weave only. This ensures compatibility with 1080i50/60 with only little less coding efficiency than 1080p25/30 and half the bandwidth requirement of 1080p50/60, but the SDTV problems of PAL speed-up and Telecine judder remain.

It is less efficient to transmit any signal with a frame rate significantly higher than that of its source, which is 24fps for movies, however frame differencing in the compression standards used for HDTV transmission greatly reduce the wasted bandwidth in these cases.

1080p

Reprinted from Wikipedia

1080p is the shorthand name for a category of video modes. The number 1080 represents 1,080 lines of vertical resolution[1], while the letter p stands for progressive scan or non-interlaced. 1080p is considered an HDTV video mode. The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal (display) resolution of 1920 dots across and a frame resolution of 1920 × 1080 or over two million pixels. The frame rate in hertz can be either implied by the context or specified after the letter p (such as 1080p30, meaning 30 frames per second).
1080p is sometimes referred to in marketing materials as "True High-Definition" or "Full High-Definition". 1080p is currently the digital standard for filming digital motion pictures. Directors such as George Lucas (in Star Wars Episode III: Revenge of the Sith) shoot their digital films in this high definition mode to be shown in theaters equipped with 1080p digital projectors.

Broadcasting standards

Due to bandwidth limitations of broadcast frequencies, the ATSC and DVB have standardized only the frame rates of 24, 25, and 30 frames per second (1080p24, 1080p25, 1080p30). 1080p30 is currently the most bandwidth-intensive video mode supported. If the standard MPEG-2 compression is used, versions with higher frame rate such as 1080p50 and 1080p60 could only be sent over higher-bandwidth channels; to send these over normal-bandwidth channels, a more modern codec such as the H.264/MPEG-4 AVC codec must be used. Higher frame rates such as 1080p50 and 1080p60 are currently for private or internal use only, and are not part of the broadcasting standard.

The ATSC is considering amending its standard to allow the incorporation of the newer codecs for optional usage like the DVB Consortium already has done with DVB-S2. However, doing so is not expected to result in widespread consumer availability of broadcast 1080p programming, since most of the existing digital television sets or external digital receivers 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 (i.e. both a 1080i or 720p MPEG-2 stream alongside a 1080p MPEG-4 stream) on the same broadcast channel.

Production standards

A new high-definition progressive scan format for picture creation is currently being developed to operate at 1080p at 50 or 60 frames per second. 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 field interlace 1920 × 1080 from 1.485 Gb/s to nominally 3 Gb/s. It is unable to be broadcast in a compressed transmission to current MPEG-2 based HD receivers. This format will improve final pictures because of the benefits of "oversampling" and removal of interlace artifacts.

1080i film-based content can become true 1080p

The following examples refer to content that is encoded in progressive-scan form during recording or transmission—what would be considered "native" progressive signals. However, where 24 fps film-based material is concerned, a 1080i encoded/transmitted stream can become a true "1080p" signal during playback by deinterlacing to re-combine the split field pairs into their original progressive film-scanned frames. Regarding 24 fps film-source material presented in conventional 1080i60 form, the deinterlacing process that achieves this goal is usually referred to as "3-2 pulldown reversal". The importance of this is that, where film-based content is concerned, all 1080-interlaced signals are potentially 1080p signals given the proper deinterlacing. As long as no additional image-degradation steps were applied during signal mastering (such as excessive vertical-pass filtering), the image from a properly deinterlaced film-source 1080i signal and a native-encoded 1080p signal will look exactly the same. As more and more processors and displays come to market able to apply 3-2 pulldown reversal to film-based 1080i60 signals, the amount of available "1080p" content for viewing expands (encompassing film-based 1080i60 feeds from broadcast HD, cable, and satellite).

Broadcasts

Even though various television networks in the world broadcast HDTV programming in 1080i and 720p, no 1080p broadcasting actually exists at this time. Material that has been digitized from a 35-mm film source is basically 1080p24 though, fit into 1080i50 or 1080i60 (progressive with segmented frames) and with proper 3-2 reversal deinterlacing, can be converted back into a true 1080p signal (see above explanation).

Internet Content

There has been some content released in the 1080p format on the Internet. Some notable examples include Microsoft's WMV HD Content Showcase, and the Apple trailers in HD format. 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.

Consumer televisions

There is a growing selection of consumer televisions with native 1080p at this time. Among the television sets with a 1080p resolution, however, some are not capable of both accepting and reproducing a 1080p input signal, especially via a digital input such as Digital Visual Interface (DVI) or High-Definition Multimedia Interface (HDMI).[2] In 2003, Sony released Qualia 004, a 1080p-resolution front-projector (it could not accept 1080p signals), while Mitsubishi released a 1080p rear-projection TV; both were based on LCoS technology and had limited availability. Several televisions in 2005 offered 1080p, including sets from Hewlett-Packard, Mitsubishi, Westinghouse Digital, Samsung and Sony. The 2006 Consumer Electronics Show (CES) introduced 1080p displays from most manufacturers, available in various display technologies. Also, 3-2 pulldown reversal 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

Cathode ray tube (CRT) computer monitors have long been capable of displaying (and exceeding) 1080p, albeit as a non-standard resolution since most CRT monitors have an aspect ratio of 4:3 (and those that aren't are 16:10, not 16:9). Most 17-inch computer monitors which support 1280 × 1024 at 60 Hz will accept an input signal at 1920 × 1080 at 60 Hz, although the projected resolution will exceed the physical limitations of the display screen itself, which for CRT devices is commonly documented as phosphor dot pitch. Some modern widescreen liquid crystal display (LCD) monitors can also natively display 1080p content. Widescreen WUXGA monitors for example support 1920x1200 resolution, which can display a pixel for pixel reproduction of the 1080p (1920x1080) format. These resolutions are supported by several laptops with 15.4 and 17 inch displays.

Storage format

1080p-encoded titles have been released on Blu-ray Disc and also on HD DVD[3]. However, the first generation of HD-DVD players can only output the content at 1080i resolution (see above for an explanation of why this may not lead to any difference in some cases). After a hardware generation or two, it is expected that HD DVD players will allow output of full 1080p, thereby catching up with Blu-ray disc players, which are able to output 1080p video from the first hardware generation, at least for some models (for example, the Samsung BD-P1000). Output of film-based material in conventional 1080i60 form will also be available, and 1080p displays that are able to apply 3-2 pulldown reversal could deinterlace film-based content and achieve full 1080p image quality.

1080p and near-1080p content has also been released on regular DVD-ROM disks using WMV HD compression. These titles cannot be played in normal DVD players and can only be viewed on a Windows-based computer with a (recommended) 3.0 GHz Pentium 4 processor or equivalent CPU, among other hardware requirements.[4]

Featured Product Reviews