576i is a standard-definition video mode originally used for terrestrial television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because of its close association with the colour encoding system, it is often referred to as simply PAL , PAL/SECAM or SECAM when compared to its 60 Hz (typically, see PAL-M) NTSC-colour-encoded counterpart, 480i. In digital applications it is usually referred to as "576i"; in analogue contexts it is often called "625 lines", and the aspect ratio is usually 4:3 in analogue transmission and 16:9 in digital transmission.
The 576 identifies a vertical resolution of 576 lines, and the i identifies it as an interlaced resolution. The field rate, which is 50 Hz, is sometimes included when identifying the video mode, i.e. 576i50; another notation, endorsed by both the International Telecommunication Union in BT.601 and SMPTE in SMPTE 259M, includes the frame rate, as in 576i/25.
Its basic parameters common to both analogue and digital implementations are: 576 scan lines or vertical pixels of picture content, 25 frames (giving 50 fields) per second.
In analogue 49 additional lines without image content are added to the displayed frame of 576 lines to allow time for older cathode ray tube circuits to retrace for the next frame,giving 625 lines per frame. Digital information not to be displayed as part of the image can be transmitted in the non-displayed lines; teletext and other services and test signals are often implemented.
Analogue television signals have no pixels; they are rastered in scan lines, but along each line the signal is continuous. In digital applications, the number of pixels per line is an arbitrary choice as long as it fulfils the sampling theorem. Values above about 500 pixels per line are enough for conventional free-to-air television; DVB-T, DVD and DV allow better values such as 704 or 720.
The video format can be transported by major digital television formats, ATSC, DVB and ISDB, and on DVD, and it supports aspect ratios of standard 4:3 and anamorphic 16:9.
When 576i video is transmitted via baseband (i.e., via consumer device cables, not via RF), most of the differences between the "one-letter" systems are no longer significant, other than vertical resolution and frame rate.
In this context, unqualified 576i invariably means
576i when it is transmitted over free-to-air satellite signals is transmitted substantially differently from terrestrial transmission.
Full transponder mode (e.g., 72 MHz)
Half-transponder mode (e.g., 36 MHz)
In digital video applications, such as DVDs and digital broadcasting, color encoding is no longer significant; in that context, 576i means only
There is no longer any difference (in the digital domain) between PAL and SECAM. Digital video uses its own separate color space, so even the minor color space differences between PAL and SECAM become moot in the digital domain.
When 576i is used to transmit content that was originally composed of 25 full progressive frames per second, the odd field of the frame is transmitted first. This is the opposite of NTSC. Systems which recover progressive frames, or transcode video should ensure that this field order is obeyed, otherwise the recovered frame will consist of a field from one frame and a field from an adjacent frame, resulting in 'comb' interlacing artifacts.
Motion pictures are typically shot on film at 24 frames per second. When telecined and played back at PAL's standard of 25 frames per second, films run about 4% faster. This also applies to most TV series that are shot on film or digital 24p.Unlike NTSC's telecine system, which uses 3:2 pulldown to convert the 24 frames per second to the 30 fps frame rate, PAL speed-up results in the telecined video running 4% shorter than the original film as well as the equivalent NTSC telecined video.
Depending on the sound system in use, it also slightly increases the pitch of the soundtrack by 70.67 cents (0.7067 of a semitone). More recently, digital conversion methods have used algorithms which preserve the original pitch of the soundtrack, although the frame rate conversion still results in faster playback.
Conversion methods exist that can convert 24 frames per second video to 25 frames per second with no speed increase, however image quality suffers when conversions of this type are used. This method is most commonly employed through conversions done digitally (i.e. using a computer and software like VirtualDub), and is employed in situations where the importance of preserving the speed of the video outweighs the need for image quality.
Many movie enthusiasts prefer PAL over NTSC despite the former's speed-up, because the latter results in telecine judder, a visual distortion not present in PAL sped-up video.states "the majority of authorities on the subject favour PAL over NTSC for DVD playback quality". Also DVD reviewers often make mention of this cause. For example, in his PAL vs. NTSC article, the founder of MichaelDVD says: "Personally, I find [3:2 pulldown] all but intolerable and find it very hard to watch a movie on an NTSC DVD because of it." In the DVD review of Frequency, one of his reviewers mentions: "because of the 3:2 pull-down artefacts that are associated with the NTSC format (…) I prefer PAL pretty much any day of the week". This is not an issue on modern upconverting DVD players and personal computers, as they play back 23.97 frame/s–encoded video at its true frame rate, without 3:2 pulldown.
PAL speed-up does not occur on native 25 fps video, such as British or European TV-series or movies that are shot on video instead of film.
Software which corrects the speed-up is available for those viewing 576i DVD films on their computers, WinDVD's "PAL TruSpeed" being the most ubiquitous[ citation needed ]. However, this method involves resampling the soundtrack(s), which results in a slight decrease in audio quality. There is also a DirectShow Filter for Windows called ReClock developed by RedFox (formerly SlySoft) which can be used in a custom DirectShow Graph to remap the reference audio timing clock to correct the clock timing skew using an accurate self-adaptive algorithm resulting in effective removal of judder during panning caused by Euro pulldown including audio pitch correction via time-stretching with WASAPI Exclusive Mode and SPDIF AC/3 Encoding output modes.
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
NTSC, named after the National Television System Committee, is the analog television color system that was introduced in North America in 1954 and stayed in use until digital conversion. It was one of three major analog color television standards, the others being PAL and SECAM.
Phase Alternating Line (PAL) is a colour encoding system for analogue television used in broadcast television systems in most countries broadcasting at 625-line / 50 field per second (576i). It was one of three major analogue colour television standards, the others being NTSC and SECAM.
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode ray tube (CRT) systems which were later replaced by flat panel displays of several types.
Interlaced video is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. This enhances motion perception to the viewer, and reduces flicker by taking advantage of the phi phenomenon.
Telecine is the process of transferring motion picture film into video and is performed in a color suite. The term is also used to refer to the equipment used in the post-production process. Telecine enables a motion picture, captured originally on film stock, to be viewed with standard video equipment, such as television sets, video cassette recorders (VCR), DVD, Blu-ray Disc or computers. Initially, this allowed television broadcasters to produce programmes using film, usually 16mm stock, but transmit them in the same format, and quality, as other forms of television production. Furthermore, telecine allows film producers, television producers and film distributors working in the film industry to release their products on video and allows producers to use video production equipment to complete their filmmaking projects. Within the film industry, it is also referred to as a TK, because TC is already used to designate timecode. Motion picture film scanners are similar to telecines.
Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that standard, is used mostly in the United States, Mexico, Canada, and South Korea. Several former NTSC users, in particular Japan, have not used ATSC during their digital television transition, because they adopted their own system called ISDB.
Broadcast television systems are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analog television systems in use around the world until the late 2010s (expected): NTSC, PAL, and SECAM. Now in digital terrestrial television (DTT), there are four main systems in use around the world: ATSC, DVB, ISDB and DTMB.
Enhanced-definition television, or extended-definition television (EDTV) is a Consumer Electronics Association (CEA) marketing shorthand term for certain digital television (DTV) formats and devices. Specifically, this term defines formats that deliver a picture superior to that of standard-definition television (SDTV) but not as detailed as high-definition television (HDTV).
The refresh rate is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate, which describes how many images are stored or generated every second by the device driving the display.
In video technology, 24p refers to a video format that operates at 24 frames per second frame rate with progressive scanning. Originally, 24p was used in the non-linear editing of film-originated material. Today, 24p formats are being increasingly used for aesthetic reasons in image acquisition, delivering film-like motion characteristics. Some vendors advertise 24p products as a cheaper alternative to film acquisition.
Deinterlacing is the process of converting interlaced video into a non-interlaced or progressive form. Interlaced video signals are commonly found in analog television, digital television (HDTV) when in the 1080i format, some DVD titles, and a smaller number of Blu-ray discs.
HD-MAC was a proposed broadcast television systems standard by the European Commission in 1986, a part of Eureka 95 project. It is an early attempt by the EEC to provide High-definition television (HDTV) in Europe. It is a complex mix of analogue signal, multiplexed with digital sound, and assistance data for decoding (DATV). The video signal was encoded with a modified D2-MAC encoder.
Analog high-definition television was an analog video broadcast television system developed in the 1930s to replace early experimental systems with as few as 12-lines. On 2 November 1936 the BBC began transmitting the world's first public regular analog high-definition television service from the Victorian Alexandra Palace in north London. It therefore claims to be the birthplace of television broadcasting as we know it today. John Logie Baird, Philo T. Farnsworth, and Vladimir Zworykin had each developed competing TV systems, but resolution was not the issue that separated their substantially different technologies, it was patent interference lawsuits and deployment issues given the tumultuous financial climate of the late 1920s and 1930s.
MUSE, was an analog high-definition television system, using dot-interlacing and digital video compression to deliver 1125-line high definition video signals to the home. Japan had the earliest working HDTV system, which was named Hi-Vision with design efforts going back to 1979. The country began broadcasting wideband analog HDTV signals in 1989 using 1035 active lines interlaced in the standard 2:1 ratio (1035i) with 1125 lines total. By the time of its commercial launch in 1991, digital HDTV was already under development in the United States. Hi-Vision continued broadcasting in analog until 2007.
Three-two pull down is a term used in filmmaking and television production for the post-production process of transferring film to video.
Television standards conversion is the process of changing a television transmission or recording from one television system to another. The most common is from NTSC to PAL or the other way around. This is done so television programs in one nation may be viewed in a nation with a different standard. The video is fed through a video standards converter, which makes a copy in a different video system.
CCIR System A was the 405-line analog broadcast television system broadcast in the UK and Ireland. System A service was discontinued in 1985.
CCIR System I is an analog broadcast television system. It was first used in the Republic of Ireland starting in 1962 as the 625-line broadcasting standard to be used on VHF Band I and Band III, sharing Band III with 405-line System A signals radiated in the north and east of the country. The UK started its own 625-line television service in 1964 also using System I, but on UHF only – the UK has never used VHF for 625-line television except for some cable relay distribution systems.