PALplus (or PAL+) is an analogue television broadcasting system aimed to improve and enhance the PAL format while remaining compatible with existing television receivers. It followed experiences with the HD-MAC and D2-MAC, hybrid analogue-digital formats that were incompatible with PAL receivers. It was developed at the University of Dortmund in Germany, in cooperation with German terrestrial broadcasters and European and Japanese manufacturers.
In the 1980s, a new high definition broadcasting standard, HD-MAC, was created, offering twice the number of available scanning lines compared to PAL. As a transitional standard, D2-MAC was established. It had the same number of lines as PAL, but like HD-MAC it was designed for widescreen content. The MAC family of standards was adopted in Europe in 1983, primarily for Direct Broadcasting by Satellite (DBS) services.
European terrestrial broadcasters felt the need to better position themselves in order to compete with satellite and cable operators. PALplus was the name of a strategy group founded in 1989 to develop an enhanced system for terrestrial transmission compatible with PAL. While not attempting to produce HDTV standards of quality, the new format was meant to improve PAL in the following areas:
In the beginning, the task group consisted of the public broadcasting corporations of Germany (ARD and ZDF), Austria (ORF), Switzerland (SRG) and the United Kingdom (BBC and UKIB, United Kingdom Independent Broadcasters) together with the consumer electronics manufacturers Grundig, Nokia, Philips and Thomson. Sony as well as the Spanish and Portuguese broadcasters joined the group later on.
At the 1993 International Consumer Electronics Exhibition in Berlin, the first experimental PALplus broadcasts began. At the same year, the European Union approved a plan to support the production and broadcast of 16:9 programs.
In 1994 broadcasts began adopting the format and Nokia launched the first PALplus TV set in Germany.
Originally, the PALplus consortium included the following manufacturers: Philips, Grundig, Thomson, Nokia and Sony. In 1995 one of the four big Korean electronics manufacturers, Samsung, joined the PALplus consortium.
VCR manufacturers associated with the PALplus consortium were expected to launch updated VHS and S-VHS home recorders in 1995. The cost increasment compared to conventional PAL VCRs was expected to be small.
On January 1996, the PALplus board published the specifications of the standard in order to support the further dissemination of this standard for wide-screen transmissions. After German broadcasters started to broadcast some of their programmes in PAL+, the PALplus board ended its work at the end of that same year.
At the beginning of 1998, PALplus programmes were broadcast on a regular basis in nine European countries, which made PALplus the mostly used standard for widescreen transmissions in Europe at that time.
Evaluations, performed by ITU and EBU engineers in 1995-1998 concluded that the use of down-converted HDTV source material, as well as high-quality widescreen standard definition content, could be a significant benefit to the PALplus picture quality. Moreover, the experts felt that PALplus would not be out of place in an HDTV environment at viewing distances equal or farther to four heights of a television set.
It was presumed that the standard method of display of a PALplus signal would be in 625-line interlaced (50 Hz) form, although other display formats (for example, 50 Hz progressive, 100 Hz interlace, or 100 Hz progressive) could be receiver options.
A standard PAL receiver will display the 16:9 image in letterbox format with 432 active lines. This reproduces noticeably less detail than the 576 lines used for 4:3 broadcasts. A PALplus receiver can use extra information hidden in the black bars above and below the image to fully recover the 576 lines of vertical resolution.
For compatibility reasons, the horizontal bandwidth remains at 5.0 MHz. This means that a PALplus signal provides no extra horizontal resolution to compensate for the image being stretched across a wider screen. The result is a horizontal resolution that is 73% of the vertical resolution, or 51% when the Kell factor is ignored.
A special signal tells the receiver when PALplus is in use, and also whether the original content was interlaced ("Camera mode" 576i50) or progressive scanned ("Film mode" 576p25). An additional signal can enable a "Ghost Cancellation" feature.
A separate feature related to PALplus is ColourPlus, which improves colour decoding performance.
The PALplus standard comprises three extensions to standard PAL:
A broadcaster creates a PALplus signal by scaling an anamorphic 16:9 picture with 576 lines down to 432 lines, so that the picture appears letterboxed on a regular PAL TV set. For luminance, the scaling is done using a pair of matching low-pass and high-pass filters, with the low-pass result appearing in the broadcast. One out of every 4 lines of the high-pass result is then hidden in the remaining 144 black lines at the top and bottom of the picture, using the U colour subcarrier. The filtering is such that this is enough to restore the complete 576 line resolution. The use of the colour subcarrier means the signals sometimes appear as blue and yellow patterns on a regular PAL TV set.
The 16:9 PAL-plus receiver combines 432 visible lines plus 144 helper lines into 576 new visible lines. In Film mode (progressive scan), the operation is performed on a per-frame basis, while in Camera mode (interlaced) the operation is performed per-field.
The PAL colour carrier is modulated making use of correlation between 2 fields, in order to give a cleaner Y/C separation in the PAL-plus receiver. It is used with signals with high horizontal luminance frequencies (3 MHz) that share the spectrum with the chrominance signals. Colour pictures on both standard and PAL Plus receivers are enhanced.
For progressive "Film mode" material, "Fixed" Colour-Plus is used, as there is no motion between the image fields. For camera based images, "Motion Adaptive Color-Plus" (MACP) is used based on movement.
A special WSS signal tells the receiver whether 4:3/16:9/PALplus is in use, and also whether the original content was interlaced ("Camera mode") or progressive scanned ("Film mode"). An additional signal can enable a "Ghost Cancellation" feature. The bandwidth of these bits is low enough to be recorded on VHS and allow the receiver to switch to the proper format.
The standard permits using the mark "PAL-plus" if just the vertical helper reconstruction implemented, with Colour-plus being optional.
Some PALPlus compatible sets:
Most widescreen sets without any PAL-plus processing will switch the display format automatically between 4:3 and 16:9, based on the signaling bits. These sets will display only the centre 432 lines of the 4:3 image, to fill all of the 16:9 frame.
PALplus was used in the following European countries:
In Belgium, the Flemish public broadcasting service VRT had a policy that all of its self-created TV programmes are broadcast in PALplus. The commercial TV station VTM used to broadcast a lot in PALplus. Even the third broadcasting organisation SBS Belgium with its stations VT4 and VijfTV used to broadcast in PALplus for all of their new productions.
The Walloon public broadcasting service RTBF used to broadcast 16:9 programmes that it purchased in PALplus, but preferred creating their own programmes in 4:3. Walloon commercial TV station RTL-TVI used to broadcast almost all its shows in PALPlus.
In 2010 Belgium switched off analog television broadcast.
In Germany all public broadcasters (ARD, ZDF, etc) complied with this standard. However, private broadcasters (RTL, Pro Sieben, etc) have shown no interest in either this standard or in the 16:9 format.[ dubious ][ citation needed ] Pay-per-view channels such as those on Sky often broadcast in 16:9, but use a different standard that requires another kind of decoder.
In 2008 Germany switched off analog television broadcast.
In the Netherlands the public broadcasters used PALplus until 2005 but have stopped using it because they preferred digital television (anamorphic widescreen) over PALplus. The public broadcasters and all the major commercial stations have a policy of broadcasting their own and new shows in widescreen, this isn't converted to PALplus on the analogue signal of the cable operators. As cable is the most widespread form of receiving television in the Netherlands the system isn't used anymore. Terrestrial analogue signals stopped in November 2006 in this country.
In Portugal, the private broadcaster TVI began broadcasting movies in PALplus in 1994, but some years after it left the standard behind.
The public broadcaster RTP started using the format on December 5, 1997.The system was used to broadcast selected programs (about five programs each day) and some widescreen movies on analog terrestrial broadcasts. Cable distributors occasionally strip the signal of the WSS bits, rendering the system inoperative. Also, when Digital Terrestrial Television broadcasts started, there was no dedicated anamorphic simulcast for the digital channels. Therefore, PALPlus over terrestrial analog PAL broadcasts remained the only source of 576 lines widescreen TV in Portugal for many years.
Since the middle of 2010 PALPlus was dropped in favor of regular 16:9 letterbox, because the system caused considerable image degradation (with an effective horizontal resolution of only about ~400px compared to 720px of a digital SDTV image) when used on digital transmissions. After that, with the end of analog broadcasts by 2012, the system became officially obsolete.
In Finland, the commercial broadcaster MTV3 started broadcasting the youth music program Jyrki in PALplus format on August 18, 1997. The experiment ended when the program ended some four years later.
In 2007 Finland switched off analog television broadcast.
In Greece, there used to be sporadic PALplus broadcasts, on the national television (E.R.T. - Hellenic Radio Television). Throughout the '90s, there were a few attempts from commercial broadcasters to adopt the system, but they all failed to gain popularity.
Because of the nature of ERT's broadcasting equipment, events and documentaries shot by ERT in PALPlus used to be broadcast as such, as they left control room to be distributed. However, PALplus reaching audiences is a different story. PALplus is not preserved when content is distributed via NOVA, due to heavy MPEG encoding since WSS signaling and additional information embedded in PALplus are seriously degraded to the extent that renders them no longer decodable. As some of the repeaters of ERT's channels are fed via OTE (Greek public telecom provider) in uncompressed form over terrestrial links, and others are fed via NOVA (Greece's only satellite platform) it depends on each repeater's feed source whether the content terrestrially broadcast (VHF - UHF) is PALplus or not.
In Spain, the Catalan public television, TV3, trialled the PALplus format in the late 1990s, with a weekly broadcast of a film in this format. Other public regional stations (like Galicia's TVG) tested the format too, but after these trials the technology was dropped and 16:9 digital broadcasts were not introduced until 2007.
In the United Kingdom, Channel 4 used to broadcast selected films as PALplus during the mid to late 1990s. Some programmes, including Fifteen to One and the omnibus edition of Brookside were also broadcast this way. All of the six main broadcasters, BBC, ITV, Channel 4, Five, Sky and Virgin Media, now all broadcast in digital.
Analog television broadcast was switched off in the United Kingdom in 2012.
Digital television (DTV) is the transmission of television audiovisual signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high definition (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio in contrast to the narrower format of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same bandwidth as a single analog channel, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2000. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:
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.
Standard-definition television is a television system which uses a resolution that is not considered to be either high or enhanced definition. SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions. "Standard" refers to the fact that it was the prevailing specification for broadcast television in the mid- to late-20th century.
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.
Widescreen images are images that are displayed within a set of aspect ratios used in film, television and computer screens. In film, a widescreen film is any film image with a width-to-height aspect ratio greater than the standard 1.37:1 Academy aspect ratio provided by 35 mm film.
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.
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.
Anamorphic widescreen is a process by which a comparatively wide widescreen image is horizontally compressed to fit into a storage medium with a narrower aspect ratio, reducing the horizontal resolution of the image while keeping its full original vertical resolution. Compatible play-back equipment can then expand the horizontal dimension to show the original widescreen image. This is typically used to allow one to store widescreen images on a medium that was originally intended for a narrower ratio, while using as much of the frame – and therefore recording as much detail – as possible.
In television technology, widescreen signaling (WSS) is a digital stream embedded in the analog TV signal describing qualities of the broadcast, in particular the intended aspect ratio of the image. This can be used by a widescreen TV or other device to switch to the correct display mode.
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 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.
576p is the shorthand name for a video display resolution. The p stands for progressive scan, i.e. non-interlaced, the 576 for a vertical resolution of 576 pixels, usually with a horizontal resolution of 720 or 704 pixels. The frame rate can be given explicitly after the letter.
High-definition video is video of higher resolution and quality than standard-definition. While there is no standardized meaning for high-definition, generally any video image with considerably more than 480 vertical scan lines or 576 vertical lines (Europe) is considered high-definition. 480 scan lines is generally the minimum even though the majority of systems greatly exceed that. Images of standard resolution captured at rates faster than normal, by a high-speed camera may be considered high-definition in some contexts. Some television series shot on high-definition video are made to look as if they have been shot on film, a technique which is often known as filmizing.
Low-definition television (LDTV) refers to TV systems that have a lower screen resolution than standard-definition TV systems. The term is usually used in reference to digital TV, in particular when broadcasting at the same resolution as low-definition analog TV systems. Mobile DTV systems usually transmit in low definition, as do all slow-scan TV systems.
Multiplexed analogue components (MAC) was a satellite television transmission standard, originally proposed for use on a Europe-wide terrestrial HDTV system, although it was never used terrestrially.
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.
Broadcast-safe video is a term used in the broadcast industry to define video and audio compliant with the technical or regulatory broadcast requirements of the target area or region the feed might be broadcasting to. In the United States, the Federal Communications Commission (FCC) is the regulatory authority; in most of Europe, standards are set by the European Broadcasting Union (EBU).
High-definition television (HD) describes a television system providing an image resolution of substantially higher resolution than the previous generation of technologies. The term has been used since 1936, but in modern times refers to the generation following standard-definition television (SDTV), often abbreviated to HDTV or HD-TV. It is the current de facto standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television and Blu-ray Discs.