History Platform / CompactDisc

The first form of digital UsefulNotes/OpticalDisc, the first digital consumer media format, and one of the three most popular and ubiquitous forms (the others being Platform/{{DVD}} and Platform/BluRay). Compact Discs, or [=CDs=] as they are generally known, are usually 12 centimetres (approx. 5") across and are shiny on at least one side (the one without a label painted or burned on). They are mostly used for two things: Music and computer data. Yes, all those free coasters from your favorite ISP were compact discs, and the ones on sale for ten bucks at the checkout counter at the Korean grocery stores still are. The two can overlap--Platform/MP3 [=CDs=] are gaining popularity. They're "compact" because they're smaller than phonograph records. The CD was probably one of the world's most influential physical media formats since the invention of film stock and was probably the biggest format for ''any'' form of media prior to the advent of digital distribution, not only changing the way that music was distributed and listened to, but also affecting data distribution such as computer software and video games and serving as the basis of the DVD format, which itself would radically change home media for movies, TV shows, video games, and computer software during its own comparatively brief period of popularity. As such, there is a ''lot'' to go over in regards to the Compact Disc. What the LP was to TheSeventies and the cassette was to TheEighties, the CD was to TheNineties: the music format that was emblematic of the decade's popular culture.

The first form of digital UsefulNotes/OpticalDisc, the first digital consumer media format, and one of the three most popular and ubiquitous forms (the others being UsefulNotes/{{DVD}} and UsefulNotes/BluRay). Compact Discs, or [=CDs=] as they are generally known, are usually 12 centimetres (approx. 5") across and are shiny on at least one side (the one without a label painted or burned on). They are mostly used for two things: Music and computer data. Yes, all those free coasters from your favorite ISP were compact discs, and the ones on sale for ten bucks at the checkout counter at the Korean grocery stores still are. The two can overlap--UsefulNotes/MP3 [=CDs=] are gaining popularity. They're "compact" because they're smaller than phonograph records. The CD was probably one of the world's most influential physical media formats since the invention of film stock and was probably the biggest format for ''any'' form of media prior to the advent of digital distribution, not only changing the way that music was distributed and listened to, but also affecting data distribution such as computer software and video games and serving as the basis of the DVD format, which itself would radically change home media for movies, TV shows, video games, and computer software during its own comparatively brief period of popularity. As such, there is a ''lot'' to go over in regards to the Compact Disc. What the LP was to TheSeventies and the cassette was to TheEighties, the CD was to TheNineties: the music format that was emblematic of the decade's popular culture.

The Compact Disc was actually the result of two different formats for a digital optical disc coming together. In 1974, both Sony and Philips aimed to devise a successor to the vinyl record that eliminated the issue of surface noise and playback degradation, both of which were problems that both audiophiles and musicians long sought to minimize as much as possible. Philips initially started with an analog optical disc akin to their earlier UsefulNotes/LaserDisc video format (and shifted focus to their audio disc when [=LaserDisc=] began struggling), but due to a lack of satisfactory results shifted focus to creating an optical disc that used digital data to encode and play back audio. As their design evolved, the size shrunk down from around the size of a [=LaserDisc=] to 4.5 inches, approximately the same diameter as the diagonal length of their previous compact cassette format. Sony's design, meanwhile was about the same size as a 12" long-playing record, was digital from the get-go, could hold around an hour of audio, and based its digital audio format off of that used in pulse-code modulation technology that they had developed the previous year (though the audio format itself was more similar to the data encoding format used for floppy disks). Both companies based their prototypes off of a 1966 patent by American inventor James T. Russel, who envisioned the idea of using a halogen lamp to read optically-encoded data off of a transparent foil, and would license out this patent following litigation in the 1980's, with Russel earning 26 patents for CD-ROM technology by 1985.\\\

Unlike with the UsefulNotes/LaserDisc, the initial lack of ability for consumers to record on the CD didn't seem to hamper adoption, as many prospective buyers already had cassette decks for that purpose. The CD even complemented the cassette by making it easy to cue up tracks for making mix tapes, and the CD's clarity made it a perfect source for such home taping.\\\

Incidentally, the CD's odd sample rate (44.1 kHz, which is tough to convert from since it's not an even multiple of 8000 like most other formats) was chosen because it matches well with both NTSC and PAL monochrome video carriers. This is because early digital audio work used a VCR with a device called a "PCM adapter" attached for data transfer. Back in 1980, when the CD-DA format was being worked on, multi-megabyte hard drives were still very much the realm of data centers, and tape provided the needed capacity in a package that was far less expensive and more portable. The video tape connection is also why [=CDs=] give their block addresses in minutes, seconds and frames -- it's carried over from the SMPTE time code used on [[UsefulNotes/UMatic U-Matic]] tapes, though running at 75 frames per second instead of the normal 25 or 30. Similar digital-to-analog converters that connected to standard VHS and Beta recorders were sold to audiophiles in the 1980s, with a few prerecorded titles on tape available, but digital audio on videotapes remained a niche format outside of recording studios. Some audiophiles still use external [=DACs=] for their CD players today, out of a belief that they're better than the ones in the CD player.\\\

Probably the least successful foray of note that the CD tried to undertake was tapping into the home media market. The first such attempt at this was with the CD Video format in 1987, which divided the disc between an inner audio CD segment and an outer UsefulNotes/LaserDisc segment in an attempt to use the CD format's success to push greater sales of [=LaserDisc=] players. The format also enabled the creation of 7" and 12" video-only [=LaserDiscs=] that could sync up the analog video track with a Red Book audio track, with this variant being used for feature films as well as music releases (these also carried over the "CD Video" branding, even if the only "CD" element on them was the digital audio). To help buyers differentiate these from regular [=CDs=] and [=LaserDiscs=], CD Video discs featured translucent yellow polycarbonate, giving them a faux gold appearance.\\\

* The Black Book, which isn't an official Rainbow Book standard but is rather an umbrella category used for any optical disc format that doesn't meet the standards of any of the other Rainbow Books. Creator/{{Nintendo}}'s proprietary disc formats for the Platform/NintendoGameCube, Platform/{{Wii}}, and Platform/WiiU are among the most well-known entrants in the Black Book, as are UsefulNotes/{{DVD}} and UsefulNotes/BluRay discs themselves (the Scarlet Book standard, described in more detail below, is incidentally an offshoot of the DVD format, though is still counted among the official Rainbow Books in part due to their compatibility with Red Book technology and because both Sony and Philips were the sole participants in its creation).

As with UsefulNotes/{{DVD}} and UsefulNotes/BluRay video, [=CDs=] remain popular among collectors who like having physical copies of albums (at least those who haven't jumped on the vinyl revival bandwagon) as well as people who lack reliable access to broadband and thus lack access to digital music services. They also still have a niche in automotive use as cassettes did in the '90s, but again are being rapidly superseded by Bluetooth connections to smartphones playing streaming music in new cars. Even if the CD has fallen quite heavily from its peak in 2000, it's certainly far from dead. Sales and revenues of [=CDs=] in American actually grew in 2021, according to the RIAA, showing that the format does have some life yet 40 years from its introduction.\\\

The standard for [=CDs=] declares only a maximum size: 12cm. Undersized and oddly shaped [=CDs=] did and still do fly around; there are structural requirements when you spin a disc at thousands of revolutions per minute, but heart-shaped and square [=CDs=] are sturdy enough for novelty stores. Business card-sized [=CDs=] are still popular in some technical circles, especially for groups that provide electronic media. Early on, there were hopes that the 8cm (approx. 3") audio CD would make a good single format, but these plans ended up slighted due to two prominent factors. Firstly, 12cm discs were simply cheaper to produce than 8cm ones. Secondly (and perhaps more prominently), there was the lack of foresight on account of the CD player manufacturers: most early players were only really built to fit 12cm [=CDs=], with 8cm discs requiring snap-on adapters just to be able to fit in the tray, and most slot-loaders won't unload 8cm [=CDs=] thanks to not having compatible grips built into them.[[note]]The Creator/{{Nintendo}} UsefulNotes/{{Wii}} and Creator/{{Sony}} UsefulNotes/PlayStation3's slot drives are among the few that can load and unload both 12cm discs and 8cm discs, featuring different pairs of grips for each size. Even then, in the Wii's case this is only because the console is backwards-compatible with 8cm UsefulNotes/NintendoGameCube discs; Nintendo's notorious penny-pinching and fear of piracy meant that none of their disc-based consoles support industry standard formats like the Compact Disc. Meanwhile, the only personal-computer model to feature guaranteed slot-load capability of 8cm [=CDs=] was the slot-load DVD-ROM drive of the short-lived Power Macintosh G4 Cube.[[/note]]\\\

Regardless, the difficulties with 8cm discs doomed them from ever taking off as ''the'' format for CD singles; they were, however, more popularly supported in Japan and Europe than in the US. Europe quickly shifted over to full-sized discs come the 90's, both because of the aforementioned technical hurdles and because the larger size was a better fit for the maxi singles that came to supplant 12" singles in the dance scene, since the larger capacity allowed for more and/or even longer remixes and B-sides per release. In Japan meanwhile, mini CD singles stuck around all the way into the early 2000's, later getting a small revival in the late 2010's. Since their decline, mini CD releases are generally limited to novelty appeal at most or to deliver software small enough to fit on one (with this practice also being carried over to mini [=DVDs=] and mini Blu-rays); a small number of physical UsefulNotes/NintendoSwitch games also include soundtrack samplers on mini [=CDs=], as full-sized ones are too large to fit in the small keep cases.\\\

While the CD Video format died an early death, it did pave the way for another video-based CD format: the Video Compact Disc, also known as Video CD or VCD, which debuted in 1993. Unlike CD Video discs, [=VCDs=] were all-digital, encoding video data in the lossy MPEG-1 file format within the White Book standard. Both video quality and program length (about an hour) are less than with [=DVDs=], though DVD players and many CD-based game consoles are capable of playing them. [=VCDs=] never really caught on in the Western world, where most people stayed with VHS until [=DVDs=] came along, but became very popular in some Asian countries, to the point where the UsefulNotes/SegaSaturn (itself also highly popular in Japan) supports the format via a special MPEG cartridge. The discs were advertised as having VHS-level picture quality, and indeed the difference between the two tended to be tangential at most when using an actual VCD player or VCD-compatible game console; the lack of playback degradation also allowed a VCD's image quality to hold up after repeated plays. However, the format quickly faded into obscurity as a result of four major factors:

Nowhere was the success of [=CD-ROMs=] more prominent than with video games: nearly every optical disc-based console uses [=CDs=] for some or all of its games, and all CD-compatible consoles are additionally able to double as CD players; some systems are even compatible with [=CD+Gs=] and [=VCDs=]. The UsefulNotes/SegaDreamcast used a custom one-gigabyte version of the CD-ROM called the "GD-ROM" format instead of [=CDs=] or [=DVDs=] as a cost-saving and anti-piracy measure--which would have worked better if their GD-ROM player didn't also play normal data [=CDs=] (often, the GD-ROM contents minus copy protection pieces would fit on a CD-ROM). The use of [=CDs=] and optical discs in general as a storage medium for video games had a rocky start: the first CD-compatible system, the [[UsefulNotes/TurboGrafx16 PC Engine CD]], was a major commercial success in Japan almost immediately upon its 1988 introduction, but its 1989 international counterpart, the [=TurboGrafx-CD=], failed to make any market headway (in part because the base [=TurboGrafx-16=] never made any major market headway to begin with; more on that on its own page), and competing systems couldn't match even that level of success, [[UsefulNotes/SNESCDRom if they ever came out at all]]. However, the huge Japanese success of the UsefulNotes/SegaSaturn and the even greater international success of the UsefulNotes/PlayStation (developed by Sony, sure enough), both in the late 90's, ended up standardizing optical discs for game consoles, with later generations incorporating DVD-ROM and BD-ROM technology as well.\\\

* The Green Book, used solely for Philips' "Compact Disc Interactive" format, abbreviated as CD-i. If that name sounds familiar, it's because it was designed specifically for [[UsefulNotes/PhilipsCDi the multimedia device]] of the same name as an early means of providing multimedia functionality to Compact Discs. It never got that far off the ground, and today it's only really remembered as a prototype for both the [=VCD=] and CD-ROM formats simultaneously.

* The Black Book, which isn't an official Rainbow Book standard but is rather an umbrella category used for any optical disc format that doesn't meet the standards of any of the other Rainbow Books. Creator/{{Nintendo}}'s proprietary disc formats for the UsefulNotes/NintendoGameCube, UsefulNotes/{{Wii}}, and UsefulNotes/WiiU are among the most well-known entrants in the Black Book, as are UsefulNotes/{{DVD}} and UsefulNotes/BluRay discs themselves (the Scarlet Book standard, described in more detail below, is incidentally an offshoot of the DVD format, though is still counted among the official Rainbow Books in part due to their compatibility with Red Book technology and because both Sony and Philips were the sole participants in its creation).

Longboxes subsequently became collector's items because most of them were thrown away, making them rare in the wild, with custom-designed ones (as opposed to generic boxes that were just a small photo of the album cover against a plain backdrop, which were especially common for early CD releases) being especially coveted. Used discs are worth significantly more with a longbox, even if the release is common. After the curtailment of longboxes for mainstream releases, Sony used them for its "[=MasterSound=]" line of gold audiophile CD reissues. One legacy of the longbox design was the vertical orientation of some CD box sets released in that era. Costco and other warehouse clubs also sold [=CDs=] in longboxes long after labels stopped issuing them, but these were just standard CD releases packaged in generic longboxes with windows cut out to show the front and the back of the jewel case. That said, ones with designs supplied by the studio were eventually reinstated in these locations, albeit for [=DVDs=] (in part because that format has a more visible market today than [=CDs=]). The use of longboxes in this niche was likely a cost-cutting measure to save these stores the expense of those plastic frames and having to train employees to use them. The idea behind the longbox format also lingered in the taller, thicker jewel cases for games on early CD-ROM-based game consoles like the [[UsefulNotes/SegaGenesis Sega CD]], UsefulNotes/SegaSaturn, UsefulNotes/ThreeDOInteractiveMultiplayer, and UsefulNotes/PlayStation (albeit only for early releases in the case of the latter two, which shifted to standard jewel cases shortly after). Longboxes were also occasionally used for budget-priced PC CD-ROM games.

All in all, despite its ambition, the SACD faced too many challenges against it, and it failed to make any real impact among mainstream music listeners. Sony tried to give the SACD one last push in 2006 by adding Scarlet Book support to the UsefulNotes/PlayStation3, but in the end the format went belly-up and the [=PS3=] removed SACD compatibility starting with the third generation revision; the fact that the [=PS3=] had an incredibly botched launch didn't help (more about that on the console's own page). Despite all this, the SACD still maintains a stable niche with digital audiophiles, and new releases on the format are still coming out to this day (albeit at a much smaller scale), typically as [[LimitedSpecialCollectorsUltimateEdition limited-edition reissues]] on dedicated audiophile labels such as Mobile Fidelity Sound Lab and Audio Fidelity. Additionally, certain types of DVD, Blu-ray, and UHD Blu-ray players still maintain compatibility with [=SACDs=], long after Sony themselves threw in the towel on the format.\\\

In its original form, the format can hold up to about 650 megabytes of data[[labelnote:*]]using CD-ROM Mode 1 or CD-ROM XA Mode 2 Form 1, both using 2,048 bytes per sector (1/75 of a second); Mode 2 CD-[=ROMs=] can hold ~742 MB of data (2,336 bytes per sector), and CD-ROM XA Mode 2 Form 2 can hold up to ~738 MB (2,324 bytes per sector), with audio [=CDs=] using all 2,352 bytes per sector and allowing a capacity of almost 747 MB[[/labelnote]] or 74 minutes of Red Book audio[[labelnote:*]]Philips states a "theoretical" maximum playing time of about 79 minutes 58 seconds according to disc geometry; the limit was capped to 74 minutes to allow for practical limitations and manufacturing tolerances[[/labelnote]], a figure allegedly chosen because it was just enough to hold all of Music/LudwigVanBeethoven's Ninth Symphony, specifically the [[https://www.youtube.com/watch?v=dHDXdbSWu0E 1951 Bayreuth Festival]] performance (this legend has since been debunked; among other things, the actual recording is too long to fit on a single Red Book-compliant CD). Unofficial revisions pushed this limit up to 870 megabytes of data or 99 minutes of audio, though recording and playback problems with existing 99-minute [=CD-Rs=] have kept anyone from using discs that long for pressed [=CDs=]. Data [=CDs=] these days usually hold 700 megabytes, with their audio equivalent usually going up to a maximum of 80 minutes. Again, this is considered unofficial due to it breaking strict Red Book standards, though that hasn't stopped anyone. Music [=CDs=] are about the same as they ever have been, since the record labels rarely use all 74 minutes[[note]]most popular music albums only run to around 40-50 minutes[[/note]]; the emergence of the unofficial 80-minute CD did allow for certain double albums that were [[ReCut edited for length]][[note]]some notable victims of the 74-minute limit are the first CD versions of Music/FleetwoodMac's ''Music/{{Tusk}}'', Music/{{Prince}}'s ''1999'' and Music/{{The Cure|Band}}'s ''Kiss Me, Kiss Me, Kiss Me'', all of which had tracks edited down or removed[[/note]] or [[MultiDiscWork packaged across two discs]] on previous CD releases to be reissued uncut on one disc, though albums that go over the 80-minute mark still see edits or multi-disc CD releases (typically the latter, though the former still pops up on rare occasions). As the format gained traction in the consumer market after the mid-1980s, the inverse happened to vinyl, with LP releases being edited or spread across multiple discs as artists made longer albums with the CD format in mind. Currently, the two longest audio [=CDs=] ever released are both discs of German PopPunk band Die Ärzte's 2006 GreatestHitsAlbum ''Bäst of'' -- disc one clocks in at 88:41, disc 2 at 89:07. Not every CD a record label releases is a music CD, however; if it also contains music videos, then it's a data CD. That kind may be marked "enhanced."\\\