HD-MAC
Encyclopedia
HD-MAC was a proposed broadcast television systems standard by the European Commission
in 1986 (MAC
standard) . It was an early attempt by the EEC to provide High-definition television
(HDTV) in Europe
. It was a complex mix of analogue signal (Multiplexed Analogue Components
), multiplexed with digital sound. The video signal ( 1250 (1152 visible) lines/50 frames in 16:9
aspect ratio) was encoded with a modified D2-MAC encoder.
HD-MAC could be decoded by a standard D2-MAC receivers(SDTV), but in that mode only 625 (576) lines and certain artifacts were visible. To decode the signal in full resolution required a specific HD-MAC tuner.
36 MHz were required to broadcast in HD-MAC (PAL
SDTV
uses 6-, 7- (VHF
), or 8 MHz (UHF
)). Because UHF spare bandwidth was very scarce, HD-MAC was usable "de facto" only to cable and satellite providers, where there bandwidth was less constricted. However, the standard never became popular among broadcasters. For all this, analog HDTV could not replace conventional SDTV(terrestrial) PAL
/SECAM
, making HD-MAC sets unattractive to potential consumers.
It was required that all high-powered satellite broadcasters to use MAC from 1986. However, the launch of middle-powered satellites by SES Astra
and the use of PAL
allowed broadcasters to bypass HD-MAC, reducing their transmission costs. HD-MAC (the high-definition variant of MAC) was left for transcontinental satellite links, however.
In the 1992 Summer Olympics
, an experimental HD-MAC broadcasting took place. 100 HD-MAC receivers (in that time, retroprojectors) in Europe were used to test the capabilities of the standard. This project was financed by the EEC. The PAL-converted signal was used by mainstream broadcasters such as SWR
, BR
and 3Sat
.
The HD-MAC standard was abandoned in 1993, and since then all EU
and EBU
efforts have focused on the DVB system (Digital Video Broadcasting), which allows both SDTV and HDTV.
The signal was captured with 50 full frames per second, each at a resolution of 2048×1152. To increase horizontal resolution of the D2-MAC norm, only its bandwidth had to be increased. This was easily done as unlike PAL
, the sound is not sent on a sub-carrier, but multiplexed with the picture. However, to increase vertical bandwidth was more complex, as the line frequency had to stay at 15'625 Hz
to be compatible with D2-MAC. This offered three choices:
As none of the three modes would have been sufficient, the choice during encoding was not made for the whole picture, but for little blocks of 8×8 pixels. The signal then contained hints that controlled which de-interlacing method the decoder should use. To fully decode the picture, the signal had to be digitized and then read from the memory several times.
Related standards:
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....
in 1986 (MAC
Multiplexed Analogue Components
Multiplexed Analogue Components was a satellite television transmission standard, originally proposed for use on a Europe-wide terrestrial HDTV system, although it was never used terrestrially.- Technical overview :...
standard) . It was an early attempt by the EEC to provide High-definition television
High-definition television
High-definition television is video that has resolution substantially higher than that of traditional television systems . HDTV has one or two million pixels per frame, roughly five times that of SD...
(HDTV) in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. It was a complex mix of analogue signal (Multiplexed Analogue Components
Multiplexed Analogue Components
Multiplexed Analogue Components was a satellite television transmission standard, originally proposed for use on a Europe-wide terrestrial HDTV system, although it was never used terrestrially.- Technical overview :...
), multiplexed with digital sound. The video signal ( 1250 (1152 visible) lines/50 frames in 16:9
16:9
16:9 is an aspect ratio with a width of 16 units and height of 9. Since 2009, it has become the most common aspect ratio for sold televisions and computer monitors and is also the international standard format of HDTV, Full HD, non-HD digital television and analog widescreen television ...
aspect ratio) was encoded with a modified D2-MAC encoder.
HD-MAC could be decoded by a standard D2-MAC receivers(SDTV), but in that mode only 625 (576) lines and certain artifacts were visible. To decode the signal in full resolution required a specific HD-MAC tuner.
36 MHz were required to broadcast in HD-MAC (PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
SDTV
Standard-definition television
Sorete-definition television is a television system that uses a resolution that is not considered to be either enhanced-definition television or high-definition television . The term is usually used in reference to digital television, in particular when broadcasting at the same resolution as...
uses 6-, 7- (VHF
Very high frequency
Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
), or 8 MHz (UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
)). Because UHF spare bandwidth was very scarce, HD-MAC was usable "de facto" only to cable and satellite providers, where there bandwidth was less constricted. However, the standard never became popular among broadcasters. For all this, analog HDTV could not replace conventional SDTV(terrestrial) PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
/SECAM
SECAM
SECAM, also written SÉCAM , is an analog color television system first used in France....
, making HD-MAC sets unattractive to potential consumers.
It was required that all high-powered satellite broadcasters to use MAC from 1986. However, the launch of middle-powered satellites by SES Astra
SES Astra
Astra is the name for the geostationary communication satellites, both individually and as a group, which are owned and operated by SES S.A., a global satellite operator based in Betzdorf, in eastern Luxembourg. The name is sometimes also used to describe the channels broadcasting from these...
and the use of PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
allowed broadcasters to bypass HD-MAC, reducing their transmission costs. HD-MAC (the high-definition variant of MAC) was left for transcontinental satellite links, however.
In the 1992 Summer Olympics
1992 Summer Olympics
The 1992 Summer Olympic Games, officially known as the Games of the XXV Olympiad, were an international multi-sport event celebrated in Barcelona, Catalonia, Spain, in 1992. The International Olympic Committee voted in 1986 to separate the Summer and Winter Games, which had been held in the same...
, an experimental HD-MAC broadcasting took place. 100 HD-MAC receivers (in that time, retroprojectors) in Europe were used to test the capabilities of the standard. This project was financed by the EEC. The PAL-converted signal was used by mainstream broadcasters such as SWR
SWR
SWR may refer to:Technology:* Standing wave ratio, a wave and antenna concept* Steel Wire ropeRadio stations:* Südwestrundfunk, a public broadcasting company for the southwest of Germany...
, BR
BR
- Places :* Bedroom* BR postcode area, a group of eight postal districts in southeast London* Baton Rouge, Louisiana* Brazil , according to:** Its two-letter country code defined in ISO 3166-1 alpha-2** The prefix for Brazil's ISO 3166-2 subdivision codes...
and 3Sat
3sat
3sat is the name of a public, advertising-free, television network in Central Europe. The programming is in German and is broadcast primarily within Germany, Austria and Switzerland .3sat was established for cultural...
.
The HD-MAC standard was abandoned in 1993, and since then all EU
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
and EBU
European Broadcasting Union
The European Broadcasting Union is a confederation of 74 broadcasting organisations from 56 countries, and 49 associate broadcasters from a further 25...
efforts have focused on the DVB system (Digital Video Broadcasting), which allows both SDTV and HDTV.
Technical details
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
, the sound is not sent on a sub-carrier, but multiplexed with the picture. However, to increase vertical bandwidth was more complex, as the line frequency had to stay at 15'625 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
to be compatible with D2-MAC. This offered three choices:
- 50 frames per second with only 288 lines for fast moving scenes
- 25 frames per second with 576 lines for normally moving scenes
- 12.5 frames per second with all 1152 lines for slow motion
As none of the three modes would have been sufficient, the choice during encoding was not made for the whole picture, but for little blocks of 8×8 pixels. The signal then contained hints that controlled which de-interlacing method the decoder should use. To fully decode the picture, the signal had to be digitized and then read from the memory several times.
See also
TV transmission systems- Analog high-definition television systemsAnalog high-definition television systemsHistorically, the term high-definition television was first used to refer to a 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...
- PALPALPAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
, what MAC technology tried to replace - SECAMSECAMSECAM, also written SÉCAM , is an analog color television system first used in France....
, what MAC technology tried to replace - A-MACA-MACA-MAC carries the digital information: sound, data-teletext on an FM subcarrier at 7 MHz. Since the vision bandwidth of a standard MAC signal is 8.4 MHz, the horizontal resolution on A-MAC has to be reduced to make room for the 7 MHz carrier...
- B-MACB-MACB-MAC is a form of analog video encoding, specifically a type of B-MAC is a form of analog video encoding, specifically a type of B-MAC is a form of analog video encoding, specifically a type of (Multiplexed Analogue Components (MAC) encoding. MAC encoding was designed in the mid 80s for use with...
- C-MACC-MACC-MAC is the variant approved by the European Broadcasting Union for satellite transmissions. The digital information is modulated using 2-4PSK , a variation of quadrature PSK where only two of the phaser angles are used....
- D-MACD-MACAmong the family of MAC or Multiplexed Analog Components systems for television broadcasting, D-MAC is a reduced bandwidth variant designed for transmission down cable....
- E-MACE-MACE-MAC is 16:9 version of C-MAC. Originally E-MAC was designed for 15:9 pictures, it later adopted the 16:9 aspect ratio. The format is backwards compatible with C-MAC. It embeds additional information in field blanking and line blanking signals. E-MAC has a lower data capacity because of this...
- S-MAC
- D2-MAC
- HD-MAC, an early high-definition television standard allowing for 2048x1152 resolution.
- DVB-SDVB-SDVB-S is an abbreviation for Digital Video Broadcasting — Satellite; it is the original Digital Video Broadcasting forward error coding and demodulation standard for satellite television and dates from 1994, in its first release, while development lasted from 1993 to 1997...
, MAC technology was replaced by this standard - DVB-TDVB-TDVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
, MAC technology was replaced by this standard
Related standards:
- NICAMNICAMNear Instantaneous Companded Audio Multiplex is an early form of lossy compression for digital audio. It was originally developed in the early 1970s for point-to-point links within broadcasting networks...
-like audio coding is used in the HD-MAC system. - Chroma subsamplingChroma subsamplingChroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance....
in TV indicated as 4:2:2, 4:1:1 etc...
External links
- Multiplexed Analogue Components in "Analog TV Broadcast Systems" by Paul Schlyter