HD-MAC (High Definition Multiplexed Analogue Components) was a broadcast television standard proposed by the European Commission in 1986, as part of Eureka 95 project. It belongs to the MAC - Multiplexed Analogue Components standard family. It is an early attempt by the EEC to provide high-definition television (HDTV) in Europe. It is a complex mix of analogue signal (based on the Multiplexed Analogue Components standard), multiplexed with digital sound, and assistance data for decoding (DATV). The video signal (1250 lines/50 fields per second in 16:9 aspect ratio, with 1152 visible lines) was encoded with a modified D2-MAC encoder. HD-MAC could be decoded by normal D2-MAC standard definition receivers, but no extra resolution was obtained and certain artifacts were visible. To decode the signal in full resolution a specific HD-MAC tuner was required .
Naming convention The European Broadcasting Union video format description is as follows: width x height [scan type: i or p] / number of full frames per second European standard definition digital broadcasts use 720×576i/25, meaning 25 interlaced frames measuring 720 pixels wide and 576 pixels high per second: odd lines (1, 3, 5 ...) are grouped to build the odd field, which is transmitted first, then it is followed by the even field containing lines 2, 4, 6... Thus, there are two fields in a frame, resulting in a field frequency of 25 × 2 = 50 Hz. The visible part of the video signal provided by an HD-MAC receiver was 1152i/25, which exactly doubles the vertical resolution of standard definition. The amount of information is multiplied by 4, considering the encoder started its operations from a 1440x1152i/25 sampling grid.
Standard history Work on HD-MAC specification started officially in May 1986. The purpose was to react against a Japanese proposal, supported by the US, which aimed to establish the NHK-designed Hi-Vision (also known as MUSE) system as a world standard. Besides preservation of the European electronic industry, there was also a need to produce a standard that would be compliant with the 50 Hz field frequency systems (used by a large majority of countries in the world). Truth be said, the precisely 60 Hz of the Japanese proposal was also worrying the US, as their NTSC M-based standard definition infrastructure used a practical frequency of 59.94 Hz, potentially leading to incompatibility problems. In September, 1988, the Japanese performed the first High Definition broadcasts of the Olympic games, using their Hi-Vision system (NHK produced material using this format since 1982). In that same month of September, Europe showed for the first time a credible alternative, namely a complete HD-MAC broadcasting chain, at IBC 88 in Brighton. This show included the first progressive scan HD video camera prototypes (Thomson/LER).
Golden SCART was developed as a transmission interface for consumer devices, a special and backward-compatible implementation of the normal SCART connection. Some television sets from Philips and Telefunken are said to have been equipped with it. For the Albertville 1992 Winter Olympics and Barcelona 1992 Summer Olympics, a public demonstration of HD-MAC broadcasting took place. 60 HD-MAC receivers for the Albertville games and 700 for the Barcelona games were set up in "Eurosites" to show the capabilities of the standard. 1250 lines (1152 visible) CRT projectors were used to create an image a few meters wide in public spaces in Barcelona for the Olympics. There were some Thomson "Space system" 16:9 CRT TV sets as well. The project sometimes used rear-projection televisions. In addition, some 80,000 viewers of D2-MAC receivers were also able to watch the channel (though not in HD). It is estimated that 350,000 people across Europe were able to see this demonstration of European HDTV. 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 also demonstrated at Seville Expo '92, exclusively using equipment designed to work with the standard such as Plumbicon and CCD cameras, direct view and rear projection CRT TVs, BCH 1000 Type B VTRs, single mode fiber optic cables, and Laserdisc players with their respective discs. Production equipment was visible to the public through windows. Because UHF spare bandwidth was very scarce, HD-MAC was usable "de facto" only to cable and satellite providers, where their bandwidth was less constricted, similarly to Hi-Vision that was only broadcast by the NHK through a dedicated satellite channel called BShi. However, the standard never became popular among broadcasters. For all this, analogue 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 use MAC from 1986. However, the launch of middle-powered satellites by SES and the use of PAL allowed broadcasters to bypass HD-MAC, reducing their transmission costs. HD-MAC was left for transcontinental satellite links, however. 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. This article about IFA 1993 provides a view of the project's status close to its end. It mentions "a special BBC compilation encoded in HD-MAC and replayed from a D1 Video Tape Recorder". HD-MAC development was stopped alongside the EUREKA project in 1996, because picture quality was not deemed to be good enough, receiving TVs didn't have enough resolution, the 16:9 aspect ratio that would later become standard was seen as exotic, and receiving TVs weren't large enough to exhibit the image quality of the standard, and those that were, were CRT TVs which made them extremely heavy.
Technical details
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