View source for Multiplexed Analogue Components

{{Short description|1980s analog television standard}}
{{Tone|date=February 2017}}
{{Use dmy dates|date=March 2015}}
[[Image:PAL and D2-MAC Transmission.png|thumb|250px|The simultaneous [[PAL]] transmission of all TV-picture elements and the multiplexed transmission of the TV picture elements with D2-MAC.]]
[[Image:Multiplexed Analogue Components transmission (real signal).png|thumb|250px|625-lines MAC signal. From left to right: digital data, chrominance and luminance. Both fields (odd and even lines) are shown.]]

'''Multiplexed Analogue Components''' ('''MAC''') was an [[analog television]] standard where [[luminance]] and [[chrominance]] components were transmitted separately.<ref>{{Cite book |last=ITU Radiocommunication Assembly |url=https://extranet.itu.int/brdocsearch/R-REC/R-REC-BO/R-REC-BO.650/R-REC-BO.650-2-199203-I/R-REC-BO.650-2-199203-I!!PDF-E.pdf#page=18 |title=RECOMMENDATION ITU-R BO.650-2 - Standards for conventional television systems for satellite broadcasting in the channels defined by Appendix 30 of the Radio Regulations |year=1992 |pages=18}}</ref><ref name="auto1">{{Cite web|url=https://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?lang=eng&i=1&index=ent&codom2nd_wet=1&srchtxt=D2-MAC|title=D2-MAC [1 record] - TERMIUM Plus® — Search - TERMIUM Plus®|first=Public Works and Government Services Canada|last=Government of Canada|date=8 October 2009|website=www.btb.termiumplus.gc.ca}}</ref> This was an evolution from older color TV systems (such as [[PAL]] or [[SECAM]]) where there was interference between chrominance and luminance.

MAC was originally proposed in the 1980s<ref name="auto1" /> for use on a Europe-wide [[Terrestrial television|terrestrial]] [[High-definition television|HDTV]] system. Terrestrial transmission tests were conducted in France, although the system was never used for that purpose. Various variants were developed, collectively known as the "MAC/packet" family.<ref name="auto5">{{Cite journal|url=https://digital-library.theiet.org/content/journals/10.1049/jiere.1986.0020|title=Standards proposed by the EBU for satellite broadcasting and cable distribution|first1=Henri|last1=Mertens|first2=David|last2=Wood|date=1 February 1986|journal=Journal of the Institution of Electronic and Radio Engineers|volume=56|issue=2|pages=53–61|via=digital-library.theiet.org|doi=10.1049/jiere.1986.0020}}</ref>

In 1985 MAC was recommended for [[Satellite television|satellite]] and [[Cable television|cable broadcasts]] by the [[European Broadcasting Union|European Broadcasting Union (EBU)]], with specific variants for each medium. [[C-MAC|C-MAC/packet]] was intended for [[Satellite television#Direct-to-home and direct broadcast satellite|Direct Broadcast Satellite (DBS)]], [[D-MAC|D-MAC/packet]] for wide-band cable, and [[D2-MAC|D2-MAC/packet]] for both for DBS and narrow-band cable.<ref name="auto5" /><ref name="auto12">{{Cite web |last=Government of Canada |first=Public Works and Government Services Canada |date=8 October 2009 |title=D2-MAC [1 record] - TERMIUM Plus® — Search - TERMIUM Plus® |url=https://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?lang=eng&i=1&index=ent&codom2nd_wet=1&srchtxt=D2-MAC |website=www.btb.termiumplus.gc.ca}}</ref><ref name="Glossary and acronyms">{{Cite web |date=2006-02-09 |title=Glossary and acronyms |url=http://www.europa.eu.int/information_society/services/glossary/index_en.htm#m |access-date=2023-03-19 |website=Europe's Information Society|archive-url=https://web.archive.org/web/20060209144241/http://www.europa.eu.int/information_society/services/glossary/index_en.htm#m |archive-date=9 February 2006 }}</ref>

== History ==
MAC was originally developed by the [[Independent Broadcasting Authority]]<ref name="auto3">{{Cite journal|url=https://ieeexplore.ieee.org/document/5186077|title=Why IBA says MAC for Europe|first=T.S.|last=Robson|date=19 September 1982|journal=Electronics and Power|volume=28|issue=9|pages=578–580|via=IEEE Xplore|doi=10.1049/ep.1982.0302}}</ref><ref name="auto">{{Cite book |last=J.N. |first=Slater |url=https://nvhrbiblio.nl/biblio/boek/Slater%20-%20Modern%20television%20systems;%20to%20HDTV%20and%20beyond.pdf#page=69 |title=Modern Television Systems : To HDTV and Beyond |year=1991 |isbn=0-203-26370-7 |pages=60}}</ref> in the early 1980, as a system for delivering high quality pictures via direct broadcast satellites, that would be independent of European countries' choice of terrestrial colour-coding standard.<ref>{{cite web |title=World Analogue Television Standards and Waveforms - Colour Standards |url=http://www.pembers.freeserve.co.uk/World-TV-Standards/Colour-Standards.html#MAC |archive-url=https://web.archive.org/web/20140221112432/http://www.pembers.freeserve.co.uk/World-TV-Standards/Colour-Standards.html |archive-date=21 February 2014 |website=www.pembers.freeserve.co.uk}}</ref>

In 1982,<ref name="auto3"/> MAC was adopted as the transmission format for the UK's forthcoming DBS television services,<ref name="auto"/> eventually provided by [[British Satellite Broadcasting]]. The following year, MAC was adopted by the [[European Broadcasting Union|EBU]] as the standard for all DBS broadcasts.<ref name="auto5"/>

By 1986, despite there being two variants (D-MAC and D2-MAC) favoured by different countries, an [[Directive (European Union)|EU Directive]] imposed MAC on the national DBS broadcasters. The justification was to provide a stepping stone from analogue formats (PAL and SECAM) the future HD and [[digital television]], placing European TV manufacturers in a privileged position to provide the equipment required.

However, the [[SES Astra|Astra]] satellite system was also starting up at this time (the first satellite, [[Astra 1A]], was launched in 1989), operating outside of the EU's MAC requirements, due to being a non-DBS satellite.<ref>{{Cite journal |last=Kleinsteuber |first=Hans |date=2016-11-02 |title=New Media Technologies in Europe: the Politics of Satellite, HDTV and DAB |url=https://arrow.tudublin.ie/icr/vol5/iss1/2 |journal=Irish Communication Review |volume=5 |issue=1 |doi=10.21427/D7FB12 |issn=0791-0010}}</ref><ref>{{Citation |last1=Krieger |first1=Jörn |title=07 Astra Cracks the German Market |date=2011 |url=https://doi.org/10.1007/978-3-642-12009-1_7 |work=High Above: The untold story of Astra, Europe's leading satellite company |pages=100–107 |editor-last=Forrester |editor-first=Chris |access-date=2023-03-19 |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-642-12009-1_7 |isbn=978-3-642-12009-1 |last2=Forrester |first2=Chris}}</ref>

Despite further pressure from the [[European Union|EU]] (including a Directive to make MAC compulsory in TV sets, and subsidies to broadcasters using MAC), most broadcasters outside of Scandinavia preferred the lower costs of PAL equipment, and the system had a limited adoption.<ref>{{Cite journal |last=Pauchon |first=B. |date=1992 |title=Analogue HDTV In Europe - What are the key issues with analogue HDTV/EDTV systems ? |url=https://tech.ebu.ch/docs/techreview/trev_253-analogue.pdf#page=2 |journal=EBU Technical Review |volume=Autumn 1992 |pages=7}}</ref>

In the 2000s, the use of D-MAC and D2-MAC ceased when satellite broadcasts changed to [[DVB-S]] format.<ref>''High Above'' Broadgate Publications (April, 2010).</ref>

== Broadcast Variants ==
A number of broadcast variants exist, according to the way the digital signals are multiplexed with the MAC vision signal.<ref>{{Cite book |url=https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BO.1074-1-1990-PDF-E.pdf#page=3 |title=Report 1074-1 - Satellite transmission of multiplexed analogue component (MAC) vision signals |publisher=ITU |year=1990 |pages=48}}</ref>
* [[A-MAC]] was designed as a test-bed for the MAC concept. It was never used by any broadcaster, but eventually evolved into S-MAC.
* [[B-MAC]] was used in South Africa<ref>{{Cite book|chapter-url=https://ieeexplore.ieee.org/document/49301|chapter=The SABC's TV/radio satellite distribution system|first=D.G.|last=Conradie|title=COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings|date=19 June 1988|pages=51–55|via=IEEE Xplore|doi=10.1109/COMSIG.1988.49301|isbn=0-87942-709-4|s2cid=131163463}}</ref> by [[Multichoice]], Australia<ref>{{Cite web|url=http://happy.emu.id.au/lab/rep/rep/9510/txtspace/9510_027.htm|title=8.3 Multiplexed Analogue Components Transmissions|website=happy.emu.id.au}}</ref> by [[Optus]], the US by [[Primestar]] and [[American Forces Radio and Television Service]]. It was also used in parts of Asia until 2005, when it was replaced by digital compression.
* [[C-MAC]] required a bandwidth of about 22&nbsp;MHz,<ref name="auto6">{{Cite journal |last=Buiting |first=J. |date=1990 |title=Introduction to Duobinary Encoding and Decoding |url=http://techdoc.kvindesland.no/radio/b2/20051213183809532.pdf |journal=Elektor Electronics |volume=January 1990 |pages=50–52}}</ref> making it problematic for broadcasting. It could carry eight high quality (15&nbsp;kHz bandwidth) sound channels.<ref name="auto4">{{Cite book |url=https://extranet.itu.int/brdocsearch/R-REC/R-REC-BO/R-REC-BO.650/R-REC-BO.650-2-199203-I/R-REC-BO.650-2-199203-I!!PDF-E.pdf#page=5 |title=RECOMMENDATION ITU-R BO.650-2 - Standards for conventional television systems for satellite broadcasting in the channels defined by Appendix 30 of the Radio Regulations |publisher=ITU |year=1992 |pages=5}}</ref> It has a [[Widescreen|wide-screen]] backwardly compatible variant called [[E-MAC]].
* [[D-MAC]] was a UK standard used by [[British Satellite Broadcasting]] for satellite broadcasts, needing a bandwidth of approximately 10.5&nbsp;MHz.<ref name="auto6"/> It could carry eight high quality (15&nbsp;kHz bandwidth) sound channels<ref name="auto4"/> It was used in Norway by [[NRK]], transmitting 3 radio channels and 1 TV channel at one D-MAC channel.
* [[D2-MAC]] reduces the required bandwidth to 7.8&nbsp;MHz, allowing the system to be used on cable and satellite broadcast.<ref name="auto6"/><ref name="auto12"/><ref name="Glossary and acronyms"/> It could carry four high quality (15&nbsp;kHz bandwidth)<ref name="auto4"/> or eight lower quality audio channels.<ref name="auto6"/> It was adopted by Scandinavian, German and French satellite broadcasts ([[CNBC Europe]], [[TV3 (Sweden)]], [[TV3 (Denmark)]],  [[Eurosport|EuroSport]], [[NRK1|NRK 1]],  [[TV-Sat 2]], [[TDF 1]], [[TDF 2]], etc.).<ref>{{Cite web |date=1998 |title=NORDIC SATELLITES : 5E - 1W |url=http://www.sat-net.com/listserver/sat-uk-tab/msg00380.html |access-date=2023-03-19 |website=www.sat-net.com}}</ref><ref>{{Cite web |date=1997 |title=THE NORDEN SAT-TV FREQUENCIES |url=https://probeteam.tripod.com/freq.htm |access-date=2023-03-19 |website=SAT-CODEZ}}</ref><ref name=":0">{{Cite news |last=fu |first=mali |date=1989-09-01 |title=D2-Mac ist kein Luxus-Whopper |language=de |pages=20 |work=Die Tageszeitung: taz |url=https://taz.de/!1800018/ |access-date=2023-03-19 |issn=0931-9085}}</ref><ref>{{Cite news |last1=Vulser |first1=Nicole |last2=Marti |first2=Régis |date=December 16, 1991 |title=TVHD: l'Allemagne tentée de lâcher la France sur le D2 MAC |work=Les Echos |url=https://www.lesechos.fr/1991/12/tvhd-lallemagne-tentee-de-lacher-la-france-sur-le-d2-mac-958597}}</ref><ref>{{Cite news |date=1990-10-28 |title=Fast ein Geschenk |language=de |work=Der Spiegel |url=https://www.spiegel.de/politik/fast-ein-geschenk-a-10f6214d-0002-0001-0000-000013503151 |access-date=2023-03-19 |issn=2195-1349}}</ref><ref>{{Cite news |last=Fox |first=Barry |date=July 7, 1990 |title=Technology: Europe's high-definition TV catches the match |work=New Scientist |url=https://www.newscientist.com/article/mg12717243-700-technology-europes-high-definition-tv-catches-the-match/}}</ref> The system was used  until July 2006 in Scandinavia and until the mid-1990s for German and French sound channels.<ref name="auto1" />
* [[HD-MAC]] was an early high-definition television standard, allowing for 2048x1152 resolution.

== Studio (non-broadcast) MAC variants ==
S-MAC or Studio MAC is a non-broadcast variant, used mostly in North America. The main advantages of this variant are:
* Processing [[NTSC]] component signals yields better results (a higher quality image) than manipulating NTSC directly &ndash; thus the need to create S-MAC.
* It is not possible to mix standard MAC signals in the studio environment because the [[R-Y]] and [[B-Y]] components are carried on alternate lines.
* S-MAC's [[SECAM]] like approach to bandwidth reduction is technical annoyance, but most studio users are not affected by it.
* In S-MAC the luminance is compressed by 2:1 and the two chrominance signals by 4:1 so that all three may occupy the same line.
* S-MAC's vision bandwidth is 11&nbsp;MHz, only ~2.8x that of [[NTSC]]'s vision bandwidth of 4.2&nbsp;MHz.
* S-MAC can be carried on a single circuit and converted losslessly to and from C-MAC at any stage.
* S-MAC is well suited for SNG applications (AKA: news gathering trucks).

== Technical overview ==
MAC transmits [[Luminance (video)|luminance]] and [[chrominance]] data separately in time<ref name="auto2">{{Cite book |last=ITU |url=https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BO.1074-1-1990-PDF-E.pdf |title=Report 1074-1 Satellite transmission of multiplexed analogue component (MAC) vision signals |year=1990}}</ref> rather than separately in frequency (as other [[analog television]] formats do, such as [[composite video]]). This allows for full separation of the components.
The signals are also time-compressed (with ratios of 3:2 for luminance and 3:1 for chrominance) and the two color difference signals are transmitted on alternate lines,<ref name=":1">{{Cite book |last=Slater |first=Jim |url=https://nvhrbiblio.nl/biblio/boek/Slater%20-%20Modern%20television%20systems;%20to%20HDTV%20and%20beyond.pdf#page=72 |title=Modern Television Systems to HDTV and beyond |year=1991 |isbn=0-203-26370-7 |pages=62–65}}</ref><ref name="auto2"/> further increasing compression. The color space was [[YPbPr]],<ref name=":1" /> with a luminance component and red blue color difference chrominance components.

=== Audio and scrambling (selective access) ===
* Audio, in a format similar to [[NICAM]] was transmitted digitally rather than as an FM sub-carrier.
* The MAC standard included a standard scrambling system, [[EuroCrypt]], a precursor to the standard [[Digital Video Broadcasting|DVB-CSA]] encryption system

=== Technical details ===
In MAC color is encoded using the [[YPbPr]] color space.<ref name=":1" /> [[Luma (video)|Luma]] (<small><math>Y'</math></small>) is derived from red, green, and blue (<small><math>R', G', B'</math></small>) after gamma-correction (formula similar to [[PAL]]): <small><math>Y'= 0.2997R' + 0.587G' + 0.1145B'</math><ref name=":1" /></small>

[[Chrominance]] is computed based on <small><math>B-Y</math></small> and <small><math>R-Y</math></small> differences, generating two compressed and weighted color-difference signals know in older MAC references as <small><math>E'{\scriptstyle\text{Um}}</math></small> and <small><math>E'{\scriptstyle\text{Vm}}</math></small> or <small><math>C{\scriptstyle\text{B}}</math></small> and <small><math>C{\scriptstyle\text{R}}</math></small>.<ref name=":1" /> To avoid any confusion, and since the signals are analogue and bi-polar, these terms were replaced by <small><math>P{\scriptstyle\text{B}}</math></small> and <small><math>P{\scriptstyle\text{R}}</math></small>.<ref name=":1" />

<small>The <math>Y'</math></small> signal range is between -0.5 and 0.5 volts while <small><math>P{\scriptstyle\text{B}}</math></small> and <small><math>P{\scriptstyle\text{R}}</math></small> signals vary between -0.65 to 0.65 volts.

The following table lists the main technical parameters of the various MAC variants:<ref name=":1" /><ref>{{Cite book |url=https://extranet.itu.int/brdocsearch/R-REC/R-REC-BO/R-REC-BO.650/R-REC-BO.650-2-199203-I/R-REC-BO.650-2-199203-I!!PDF-E.pdf#page=10 |title=RECOMMENDATION ITU-R BO.650-2 - Standards for conventional television systems for satellite broadcasting in the channels defined by Appendix 30 of the Radio Regulations |publisher=ITU |year=1992 |pages=10}}</ref>
{| class="wikitable"
|-
|
!'''B-MAC'''
!'''B-MAC'''
!'''C-MAC'''
!'''D-MAC'''
!'''D2-MAC'''
|-
|'''[[Frame rate|Frame Frequency]]'''
|29.97
| colspan="4" |25 
|-
|'''[[Raster scan|Lines per frame]]'''
|[[525 lines|525]]
| colspan="4" |[[625 lines|625]]
|-
|'''[[Aspect ratio|Aspect Ratio]]'''
| colspan="5" |4:3 / 16:9
|-
|'''[[Gamma correction|Display Gamma]]'''
|2.2
| colspan="4" |2.8
|-
|[[Chromaticity|'''Primary chromaticities''' '''(x y)''']]
| colspan="5" |Similar to [[NTSC#Colorimetry|NTSC 1953]]: Red 0.67, 0.33; Green 0.21, 0.71; Blue 0.14, 0.08
|-
|'''[[White point|White point (x y)]]'''
| colspan="5" |[[Illuminant D65|D65]] 
|-
|'''[[Luminance]]'''
| colspan="5" |<small><math>Y'= 0.2997R' + 0.587G' + 0.1145B'</math></small>
|-
|'''[[Color difference|Colour difference]]'''
|<small><math>I' = -0.27 (B' - Y') + 0.74 (R' - Y')</math></small>

<small><math>Q' = -0.41 (B' - Y') + 0.48 (R' - Y')</math></small>
| colspan="4" |<small><math>R' - Y' = 0.701R'-0.587G'-0.114B'</math></small>

<small><math>B' - Y' =-0.299R'-0.587G'-0.886B'</math></small>
|-
|'''Transmitted [[chrominance]]'''
| colspan="2" |<small><math>P'{\scriptstyle\text{B}} = 0.694 (B'-Y')</math></small>
<small><math>P'{\scriptstyle\text{R}} = 0.926 (R'- Y')</math></small>
| colspan="3" |<small><math>P'{\scriptstyle\text{B}} = 0.733(B'-Y')</math></small> 
<small><math>P'{\scriptstyle\text{R}} = 0.927(R'-Y')</math></small>
|-
|'''[[Sampling (signal processing)|Sampling]] frequency (MHz)'''
|14.318
|14.219
| colspan="3" |13.500
|-
|'''Uncompressed [[Bandwidth (signal processing)|bandwidth]] (MHz)'''
|4.2
|5.0
| colspan="3" |5.6
|-
|'''Luminance [[Clock rate|clock periods]]'''
| colspan="2" |750
| colspan="3" |696
|-
|'''Chrominance clock periods'''
| colspan="2" |375
| colspan="3" |348
|}

== MAC system innovations ==
Mathematical:
* A-MAC proved the mathematical principle that separating vision from colour for TV transmission was technologically viable.
Broadcast engineering:
* The MAC audio subsystem is very similar to [[NICAM]], so much so that identical chip-sets are used.
* D-MAC satellite broadcasts provided the first broadcast sourced [[wide-screen]] television in Europe, and HD-MAC provided the first [[HDTV]] broadcasts, in 1992.

== Technical challenges ==
Although the MAC technique is capable of superior video quality, (similar to the improvement of component video over composite in a DVD player), its major drawback was that this quality was only ever realized when the video signals being transmitted remained in component form from source to transmitter. If at any stage the video had to be handled in composite form, the necessary encoding/decoding processes would severely degrade the picture quality.
* Terrestrial TV broadcasters were never able to take full advantage of MAC image quality due to multiple interactions between their composite and component signal paths.
* ''Direct to Home'' and [[TVRO]] broadcasters were able to take advantage of MAC's improved image quality because their studios and routing facilities were far less complex.
* The success of [[NICAM]] audio for terrestrial television can be traced to the success of MAC technology. The MAC audio subsystem is nearly identical in design and function to [[NICAM]].

== Countries and territories that used MAC ==
This is a list of nations that used the MAC standard for television broadcasting:
* {{flag|South Africa}}<ref>{{Cite book |last=Conradie |first=D.G. |title=COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings |date=19 June 1988 |isbn=0-87942-709-4 |pages=51–55 |chapter=The SABC's TV/radio satellite distribution system |doi=10.1109/COMSIG.1988.49301 |chapter-url=https://ieeexplore.ieee.org/document/49301 |via=IEEE Xplore |s2cid=131163463}}</ref>
* {{flag|Australia}}<ref>{{Cite web |title=8.3 Multiplexed Analogue Components Transmissions |url=http://happy.emu.id.au/lab/rep/rep/9510/txtspace/9510_027.htm |website=happy.emu.id.au}}</ref>
* {{flag|UK}}<ref name="auto32">{{Cite journal |last=Robson |first=T.S. |date=19 September 1982 |title=Why IBA says MAC for Europe |url=https://ieeexplore.ieee.org/document/5186077 |journal=Electronics and Power |volume=28 |issue=9 |pages=578–580 |doi=10.1049/ep.1982.0302 |via=IEEE Xplore}}</ref><ref name="auto"/><ref name="auto6"/>
* {{flag|Norway}}<ref name="auto12"/><ref name="auto53">{{Cite journal |last1=Mertens |first1=Henri |last2=Wood |first2=David |date=1 February 1986 |title=Standards proposed by the EBU for satellite broadcasting and cable distribution |url=https://digital-library.theiet.org/content/journals/10.1049/jiere.1986.0020 |journal=Journal of the Institution of Electronic and Radio Engineers |volume=56 |issue=2 |pages=53–61 |doi=10.1049/jiere.1986.0020 |via=digital-library.theiet.org}}</ref>
* {{flag|Germany}}<ref name="auto53"/>
* {{flag|France}}<ref name="auto53"/>
* {{flag|USA}}

== Technological obsolescence ==
Since the vast majority of TV stations and similar installations were only wired for [[composite video]], the fitting of a MAC transmitter at the end of the chain had the effect of degrading the transmitted image quality, rather than improving it.

For this and other technical reasons, MAC systems never really caught on with broadcasters. MAC transmission technology was made obsolete by the radically new digital systems (like [[DVB-T]] and [[ATSC Standards|ATSC]]) in the late 1990s.

== See also ==
TV transmission systems:
* [[Analog high-definition television system]]s
* [[PAL]], what MAC technology tried to replace
* [[SECAM]], what MAC technology tried to replace
* [[DVB-S]], MAC technology was replaced by this standard
* [[DVB-T]], MAC technology was replaced by this standard

== References ==
<references/>

== External links ==
* [http://www.stjarnhimlen.se/tv/tv.html#MAC Multiplexed Analogue Components] in "Analog TV Broadcast Systems" by Paul Schlyter
* [https://www.youtube.com/watch?v=ACywc_cZSKY IBA Engineering Announcement broadcast 3 February 1987] with more information on MAC

{{Video formats}}
{{High-definition}}

[[Category:High-definition television]]
[[Category:Satellite television]]
[[Category:Television transmission standards]]
[[Category:Television technology]]
[[Category:British inventions]]
[[Category:1982 introductions]]
[[Category:Audiovisual introductions in 1982]]
[[Category:Video formats]]