DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only'rewritable' discs are able to erase and rewrite data. Data is written to the disc by a laser, rather than the data being'pressed' onto the disc during manufacture, like a DVD-ROM. Pressing is used in mass production for the distribution of home video. Like CD-Rs, DVD recordable uses dye to store the data. During the burning of a single bit, the laser's intensity affects the reflective properties of the burned dye. By varying the laser intensity high density data is written in precise tracks. Since written tracks are made of darkened dye, the data side of a recordable DVD has a distinct color. Burned DVDs have a higher failure-to-read chance than Pressed DVDs, due to differences in the reflective properties of dye compared to the aluminum substrate of pressed discs; the larger storage capacity of a DVD-R compared to a CD-R is achieved by focusing the laser to a smaller point, creating smaller'pits' as well as a finer track pitch of the groove spiral which guides the laser beam.
These two changes allow more pits to be written in the same physical disc area, giving higher data density. The smaller focus is possible with a shorter wavelength'red' laser of 640 nm, compared to CD-R's wavelength of 780 nm; this is used in conjunction with a higher numerical aperture lens. The dyes used in each case are different. "R" format DVDs can read arbitrarily many times. Thus, "R" format discs are only suited to non-volatile data storage, such as audio, or video; this can cause confusion because the'DVD+RW Alliance' logo is a stylized'RW'. Thus, many discs are not rewritable. According to Pioneer, DVD-RW discs may be written to about 1,000 times before needing replacement. RW discs are used to store volatile data, such as when creating backups or collections of files which are subject to change and re-writes, they are ideal for home DVD video recorders, where it is advantageous to have a rewritable format capable of digital video data speeds, while being removable and inexpensive. Another benefit to using a rewritable disc is, if the burning process produces errors or corrupted data, it can be written over again, corrected.
The DVD-R format was developed by Pioneer in 1997. It is approved by the DVD Forum, it has broader playback compatibility than the “+” with much older players. The dash format uses a “land pre-pit” method to provide ‘sector’ address information. DVD “minus” R is not correct, according to DVD-R consortium recommendations. DVD-R and DVD+R technologies are not directly compatible, which created a format war in the DVD technology industry. To reconcile the two competing formats, manufacturers created hybrid drives that could read both — most hybrid drives that handle both formats are labeled DVD±R and Super Multi and are popular. Developed by Philips and Sony with their DVD+RW Alliance; the "plus" format uses a more reliable bi-phase modulation technique to provide'sector' address information. It was introduced after the "-" format; the DVD+R format was developed by a coalition of corporations—now known as the DVD+RW Alliance—in mid-2002. The DVD Forum did not approve of the DVD+R format and claimed that the DVD+R format was not an official DVD format until January 25, 2008.
On 25 January 2008, DVD6C accepted DVD+R and DVD+RW by adding them to its list of licensable DVD products. DVD+RW supports a method of writing called "lossless linking", which makes it suitable for random access and improves compatibility with DVD players; the rewritable DVD+RW standard was formalized earlier than the non-rewritable DVD+R. Although credit for developing the standard is attributed to Philips, it was "finalized" in 1997 by the DVD+RW Alliance, it was abandoned until 2001, when it was revised. As of 2006, the market for recordable DVD technology shows little sign of settling down in favour of either the plus or dash formats, the result of the increasing numbers of dual-format devices that can record to both formats, it has become difficult to find new computer drives that can only record to one of the formats. By contrast, DVD Video recorders still favour one format over the other providing restrictions on what the unfavoured format will do. However, because the DVD-R format has been in use since 1997, it has had a five-year lead on DVD+R.
As such, older or cheaper DVD players are more to favour the DVD-R standard exclusively. DVD+R discs must be formatted before being recorded by a compatible DVD video recorder. DVD-R do not have to be formatted before being recorded by a compatible DVD video recorder, because the two variants of the discs are written in different formats. There are a number of significant technical differences between the “dash” and the “plus” format, although most users would not notice the difference. One example is that the DVD+R style address in pregroove system of tracking and speed control is less susceptible to interference and error, which makes the ADIP system more accurate at higher speeds than the land pre pit system used by DVD-R. In addition, DVD+R has a more robust error-management system than DVD-R, allowing for more accurate burning to media, independent of the quality of the media; the practical upshot is
DVD-RAM is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998. DVD-RAM was one of three competing technologies for rewritable DVDs, its competitors are DVD-RW and DVD+RW. DVD-RAM technology provides good data integrity, data retention and damage protection through a number of mechanisms and properties. Therefore, DVD-RAM is perceived by people to be better than the other DVD technologies for traditional computer usage tasks such as general data storage, data backup and archival; the Mount Rainier Format standard and SecurDisc for DVD±RW somewhat lessens the DVD-RAM format's perceived advantage in the data integrity category, but not in the data retention or damage protection categories. DVD-RAM has a larger presence in camcorders and set-top boxes than in computers, although the popularity of DVD-RAM in these devices can be explained by its being easily written to and erased, which for example allows extensive in-camera editing.
The on-disc structure of DVD-RAM is related to hard disk and floppy disk technology, as it stores data in concentric tracks. DVD-RAMs can be accessed just like a hard or floppy disk and without any special software. DVD-RWs and DVD+RWs, on the other hand, store data in one long spiral track and require special packet reading/writing software to read and write data discs. Like magneto-optical technologies, DVD-RAM has numerous rectangles on the disc surface that define the boundaries of data sectors. However, DVD-RAM is not MO but a phase transition medium, similar to CD-RW, DVD-RW, or DVD+RW. Since the Internationale Funkausstellung Berlin 2003 the specification is being marketed by the RAM Promotion Group, built by Hitachi, Maxell, LG Electronics, Matsushita/Panasonic, Lite-On and Teac; the specification distinguishes between: DVD-RAM version 1.0, recording speed 1x Single-sided, one layer discs with a capacity of 2.58 GB Double-sided one layer discs with a capacity of 5.16 GB DVD-RAM version 2.0, recording speed 2x Single-sided, one layer discs with a capacity of 4.7 GB Double-sided one layer discs with a capacity of 9.4 GB DVD-RAM version 2.1/Revision 1.0, recording speed 3x DVD-RAM version 2.2/Revision 2.0, recording speed 5x DVD-RAM version 2.3/Revision 3.0, recording speed 6x max DVD-RAM version 2.4/Revision 4.0, recording speed 8x max DVD-RAM version 2.5/Revision 5.0, recording speed 12x max DVD-RAM version 2.6/Revision 6.0, recording speed 16x maxPhysically smaller, 80 mm in diameter, DVD-RAM discs exist with a capacity of 1.46 GB for a single-sided disc and 2.8 GB for a double-sided disc, but they are uncommon.
DVD-RAMs were solely sold in cartridges. Discs can be removed from cartridges for use with these drives. Many operating systems like the classic Mac OS, macOS, Microsoft Windows XP can use DVD-RAM directly, while earlier versions of Windows require separate device drivers or the program InCD. Windows XP Home and Professional can only write directly to FAT32 formatted DVD-RAM discs. For UDF formatted discs, which are considered faster, a third-party UDF file system driver capable of writing or software such as InCD or DLA are required. Windows Vista and can natively access and write to both FAT32 and UDF formatted DVD-RAM discs using mastered burning method or packet writing. Though it is possible to use any file system one likes few perform well on DVD-RAM; this is because some file systems overwrite data on the disc and the table of contents is contained at the start of the disc. It should be noted that Windows Vista implement the CPRM data protection and thus discs formatted under Windows XP have compatibility issues with Vista onwards.
The classic Mac OS up to 9.2 can read and write HFS, HFS+, FAT, UDF formatted DVD-RAM discs directly. In Mac OS X UDF-formatting of DVD-RAM is no longer supported, instead formatting and writing DVD-RAM is done in HFS+ format. Many DVD standalone players and recorders do not work with DVD-RAM. However, within "RAMPRG" there are a number of well-known manufacturers of standalone players and camcorders that can use DVD-RAM. Panasonic, for instance, has a range of players and recorders which make full use of the advantages of DVD-RAM; the newest DVD-RAM Specification, DVD-RAM2, is not compatible with DVD drives that do not allow reading DVD-RAM2 discs. Some high end products such as IBM System p mainframes require DVD-RAM instead of DVD-RW. Long life — without physical damage, data is retained for an estimated 30 years. For this reason, it is used for archival storage of data. Can be rewritten over 100,000 times for the lowest write speed discs. Faster DVD-RAMs allow fewer rewrites, but still more than DVD+RW or DVD-RW.
Reliable writing of discs. Verification done i
DVD+R DL called DVD+R9, is a derivative of the DVD+R format created by the DVD+RW Alliance. Its use was first demonstrated in October 2003. DVD+R DL discs employ two recordable dye layers, each capable of storing nearly the 4.7 GB capacity of a single-layer disc doubling the total disc capacity to 8.5 GB. Discs can only be created using DVD+R DL and Super Multi drives. DL drives started appearing on the market during mid-2004, at prices comparable to those of existing single-layer drives; as of March 2011 DL media is up to twice as expensive as single-layer media. The latest DL drives write double layer discs at a slower rate than current single-layer discs. Dual-layer recording allows DVD-R and DVD+R discs to store more data, up to 8.5 gigabytes per disc, compared with 4.7 gigabytes for single-layer discs. DVD-R DL was developed for the DVD Forum by Pioneer Corporation, while DVD+R DL was developed for the DVD+RW Alliance by Philips and Mitsubishi Kagaku Media. A dual-layer disc differs from its usual DVD counterpart by employing a second physical layer within the disc itself.
The drive with dual-layer capability accesses the second layer by shining the laser through the first semi-transparent layer. The layer change can exhibit a noticeable pause in some DVD players, up to several seconds; this caused more than just a few viewers to worry that their dual-layer discs were damaged or defective, with the end result that studios began listing a standard message explaining the dual-layer pausing effect on all dual-layer disc packaging. DVD recordable discs supporting this technology are backward compatible with some existing DVD players and DVD-ROM drives. Many current DVD recorders support dual-layer technology, the price is now comparable to that of single-layer drives, though the blank media remain more expensive; the recording speeds reached by dual-layer media are still well below those of single-layer media. There are two modes for parallel track path and opposite track path. In PTP mode, used for DVD-ROM, both layers start recording at the inside diameter with the lead-in and end at the outside diameter with the lead-out.
Sectors are sequenced from the beginning of the first layer to the end of the first layer the beginning of the second layer to the end of the second layer. In OTP mode, the second layer is read from the outside of the disk. For DVD-Video a variation of the technique is employed. DVD-Video is always recorded in OTP mode, but the video data is read from the beginning of the first layer towards the end of the first layer, when this ends reading is transferred to the second layer, but the video data commences from the same physical location that the first layer ends back towards the beginning of the second layer; this means. This is in order to minimise the time that the video player takes to locate and focus on the second layer and thus provide the shortest possible pause in the content as the layer changes. A common misconception is that the disc spins first in one direction, another, either for PTP or OTP recording, when in fact DVD-Writers always spin a disc in the clockwise direction. A simpler way to understand what's written above is to think of the little hole in the centre of the DVD as the "inside" and the rim of the DVD as the "outside".
Since dual-layer DVDs have two data layers, placed one on top of the other – Layer 0 and Layer 1, there are two ways in which these two layers may be written to - L0, inside to outside and L1 inside to outside again, or L0 inside to outside and L1 outside to inside. OTP is used for DVD-Video, to prevent the inherent delay that PTP involves: in PTP, the laser head moves from the outside edge of the DVD to the inside to start reading L1 when it reaches the end of L0; this results in the video skipping or freezing up for some time as the laser head repositions itself and the system waits to start receiving data again. For comparison, the table below shows storage capacities of the four most common DVD recordable media, excluding DVD-RAM. Stands for standard single-layer discs, while DL denotes the dual-layer variants. See articles on the formats in question for information on compatibility issues. DVD-R DL DVD DVD+R DVD+RW DVD+RW DL Book type MultiLevel Recording Bennett, Hugh. Understanding Recordable & Rewritable DVD.
Cupertino: Optical Storage Technology Association, Apr. 2004. Bennett, Hugh. "DVD±RW DL—D. O. A.?" EMedia Xtra May 10, 2005. Double-layer DVD heats up standards battle - ZDNet UK JVC's April 2005 announcement on DVD+RW DL DVD-R9 and DVD+R9 Hardware and Standards by The DVD Insider
Universal Media Disc
The Universal Media Disc is a discontinued optical disc medium developed by Sony for use on their PlayStation Portable handheld gaming and multimedia platform. It can hold up to 1.8 gigabytes of data and is capable of housing video games, feature-length films, music. UMD was the trademark of Sony Computer Entertainment for their optical disk cartridge. While the primary application for UMD discs is as a storage medium for PSP games, the format is used for the storage of motion pictures and, to a lesser degree, television shows for playback on the PSP; the video is encoded with the audio in ATRAC3plus. Video stored on UMD is encoded in 720×480 resolution, but is scaled down when displayed on the PSP; the American punk rock band The Offspring released their Complete Music Video Collection on the format. The BBC released a number of its programmes on UMD in the UK, including The Office, The Mighty Boosh, Doctor Who and Little Britain; some adult films have been released on UMD in Japan. UMD VIDEO Case dimensions: H×W×D = 177×104×14mm ECMA-365: Data Interchange on 60 mm Read-Only ODC – Capacity: 1.8 GB Dimensions: approx.
64 mm × 4.2 mm Maximum capacity: 1.80 GB, 900 MB Laser wavelength: 660 nm Numerical aperture: 0.64 Track pitch: 0.70 µm Minimum pit length: 0.1384 µm Modulation: 8-to-16 RLL Encryption: AES 128-bit According to the official ECMA specification Sony designed the UMD to support two possible future enhancements and products. Protective Shutter: Similar to the MiniDisc and 3½-inch floppy disk, this protective shutter will shield the inner disc from accidental contact. Auto-Loading: UMDs were designed for possible future slot loading devices with Auto-Loading mechanisms; these would be similar to the auto-loading mechanism used in slot loading MiniDisc home and car decks. It would be similar to the Sony U-Matic auto-loading mechanism. Unlike the current clamshell loading design the PSP uses, a slot loading device using an Auto-Loading mechanism would be motorized and automatic; the user would insert the disc into the device slot, the motorized mechanism would take over and draw the disc inside the drive completing the loading process.
The disc would be ejected automatically by the motorized mechanism, like a VCR. This would mean that power would be required in order to insert or eject a disc. In comparison to Sony's MiniDisc format the sliding shield which prevents direct disc contact on MiniDiscs is absent from all UMDs released, though it is an option according to the ECMA specification. DVD region coding has been applied to music; however regional lockout is not applied to games, making them region-free Region 0: Worldwide Region 1: Northern America + Central America Region 2: Northern Europe + Western Europe + Southern Europe + Japan + Middle East + Egypt + South Africa + Greenland + French territories + British territories Region 3: Thailand + Singapore + Malaysia + Taiwan + South Korea + Philippines + Indonesia + Hong Kong Region 4: Oceania + South America Region 5: Russia + Eastern Europe + India + Pakistan + Africa + North Korea + Mongolia Region 6: Mainland China UMDs offer large capacity and the capability to store quality audio/video content.
The UMD format never saw implementation on any device other than the PlayStation Portable, as a result the market was limited compared to those for other optical media formats. Buyers were put off by the high price of UMD releases, which retailed at comparable prices to but lacked the extra content found on DVDs. Poor sales of UMD movies early in the format's life had caused major studios Universal and Paramount to rescind their support. Retail support of the format experienced similar troubles, in 2006 Wal-Mart began phasing out shelf space devoted to UMD movies, with other chains soon following suit. By 2006 most non-specialty retail stores had stopped bringing in new UMD movies and no longer had a separate section devoted to them, with a few stray unsold titles mixed in amongst the regular PSP games. Since 2011, there have been no more movies released on UMD.. In August 2007, Multimedia Recovery brought to the market their UMD Replacement Case after many complaints from PlayStation Portable owners that the outer casing of the UMD disc was cracking or pulling apart due to the poor design, which causes the UMD to become unreadable in the PlayStation Portable.
In late 2009, Sony began pushing developers away from the UMD format and towards digital distribution on the PlayStation Network in preparation for the launch of the digital-download-only PSP Go, the first PSP model to not include a UMD drive. However the system experienced lackluster sales compared to previous models, with most consumers still choosing the UMD-compatible PSP-3000 model, which continued to be sold alongside the PSP Go. Despite the earlier push for PlayStation Network releases around the PSP Go's launch, over half of the PSP's library is still only available in UMD format including Crisis Core: Final Fantasy VII and Kingdom Hearts Birth by Sleep, though there have been a few PlayStation Network-only releases since the PSP Go's launch, such as LocoRoco Midnight Carnival. Still, most new games continue to be distributed via UMD, aside from those published by SCE, not all have been released on PlayStation Network. In 2011, the PSP-E1000, a budget PSP model with a UMD slot but without Wi-Fi, was released, is the final revision of the PlayStation Portable.
The successor of the PlayStation Portable, the PlayStation Vita
A CD-ROM is a pre-pressed optical compact disc that contains data. Computers can read—but not write to or erase—CD-ROMs, i.e. it is a type of read-only memory. During the 1990s, CD-ROMs were popularly used to distribute software and data for computers and fourth generation video game consoles; some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data is only usable on a computer. The CD-ROM format was developed by Japanese company Denon in 1982, it was an extension of Compact Disc Digital Audio, adapted the format to hold any form of digital data, with a storage capacity of 553 MiB. CD-ROM was introduced by Denon and Sony at a Japanese computer show in 1984; the Yellow Book is the technical standard. One of a set of color-bound books that contain the technical specifications for all CD formats, the Yellow Book, standardized by Sony and Philips in 1983, specifies a format for discs with a maximum capacity of 650 MiB. CD-ROMs are identical in appearance to audio CDs, data are stored and retrieved in a similar manner.
Discs are made from a 1.2 mm thick disc of polycarbonate plastic, with a thin layer of aluminium to make a reflective surface. The most common size of CD-ROM is 120 mm in diameter, though the smaller Mini CD standard with an 80 mm diameter, as well as shaped compact discs in numerous non-standard sizes and molds, are available. Data is stored on the disc as a series of microscopic indentations. A laser is shone onto the reflective surface of the disc to read the pattern of lands; because the depth of the pits is one-quarter to one-sixth of the wavelength of the laser light used to read the disc, the reflected beam's phase is shifted in relation to the incoming beam, causing destructive interference and reducing the reflected beam's intensity. This is converted into binary data. Several formats are used for data stored on compact discs, known as the Rainbow Books; the Yellow Book, published in 1988, defines the specifications for CD-ROMs, standardized in 1989 as the ISO/IEC 10149 / ECMA-130 standard.
The CD-ROM standard builds on top of the original Red Book CD-DA standard for CD audio. Other standards, such as the White Book for Video CDs, further define formats based on the CD-ROM specifications; the Yellow Book itself is not available, but the standards with the corresponding content can be downloaded for free from ISO or ECMA. There are several standards that define how to structure data files on a CD-ROM. ISO 9660 defines the standard file system for a CD-ROM. ISO 13490 is an improvement on this standard which adds support for non-sequential write-once and re-writeable discs such as CD-R and CD-RW, as well as multiple sessions; the ISO 13346 standard was designed to address most of the shortcomings of ISO 9660, a subset of it evolved into the UDF format, adopted for DVDs. The bootable CD specification was issued in January 1995, to make a CD emulate a hard disk or floppy disk, is called El Torito. Data stored on CD-ROMs follows the standard CD data encoding techniques described in the Red Book specification.
This includes cross-interleaved Reed–Solomon coding, eight-to-fourteen modulation, the use of pits and lands for coding the bits into the physical surface of the CD. The structures used to group data on a CD-ROM are derived from the Red Book. Like audio CDs, a CD-ROM sector contains 2,352 bytes of user data, composed of 98 frames, each consisting of 33-bytes. Unlike audio CDs, the data stored in these sectors corresponds to any type of digital data, not audio samples encoded according to the audio CD specification. To structure and protect this data, the CD-ROM standard further defines two sector modes, Mode 1 and Mode 2, which describe two different layouts for the data inside a sector. A track inside a CD-ROM only contains sectors in the same mode, but if multiple tracks are present in a CD-ROM, each track can have its sectors in a different mode from the rest of the tracks, they can coexist with audio CD tracks as well, the case of mixed mode CDs. Both Mode 1 and 2 sectors use the first 16 bytes for header information, but differ in the remaining 2,336 bytes due to the use of error correction bytes.
Unlike an audio CD, a CD-ROM cannot rely on error concealment by interpolation. To achieve improved error correction and detection, Mode 1, used for digital data, adds a 32-bit cyclic redundancy check code for error detection, a third layer of Reed–Solomon error correction using a Reed-Solomon Product-like Code. Mode 1 therefore contains 288 bytes per sector for error detection and correction, leaving 2,048 bytes per sector available for data. Mode 2, more appropriate for image or video data, contains no additional error detection or correction bytes, having therefore 2,336 available data bytes per sector. Note that both modes, like audio CDs, still benefit from the lower layers of error correction at the frame level. Before being stored on a disc with the techniques described above, each CD-ROM sector is scrambled to prevent some problematic patterns from showing up; these scrambled sectors follow the same encoding process described in the Red Book in order to be stored
Compact disc is a digital optical disc data storage format, co-developed by Philips and Sony and released in 1982. The format was developed to store and play only sound recordings but was adapted for storage of data. Several other formats were further derived from these, including write-once audio and data storage, rewritable media, Video Compact Disc, Super Video Compact Disc, Photo CD, PictureCD, CD-i, Enhanced Music CD; the first commercially available audio CD player, the Sony CDP-101, was released October 1982 in Japan. Standard CDs have a diameter of 120 millimetres and can hold up to about 80 minutes of uncompressed audio or about 700 MiB of data; the Mini CD has various diameters ranging from 60 to 80 millimetres. At the time of the technology's introduction in 1982, a CD could store much more data than a personal computer hard drive, which would hold 10 MB. By 2010, hard drives offered as much storage space as a thousand CDs, while their prices had plummeted to commodity level. In 2004, worldwide sales of audio CDs, CD-ROMs and CD-Rs reached about 30 billion discs.
By 2007, 200 billion CDs had been sold worldwide. From the early 2000s CDs were being replaced by other forms of digital storage and distribution, with the result that by 2010 the number of audio CDs being sold in the U. S. had dropped about 50% from their peak. In 2014, revenues from digital music services matched those from physical format sales for the first time. American inventor James T. Russell has been credited with inventing the first system to record digital information on an optical transparent foil, lit from behind by a high-power halogen lamp. Russell's patent application was filed in 1966, he was granted a patent in 1970. Following litigation and Philips licensed Russell's patents in the 1980s; the compact disc is an evolution of LaserDisc technology, where a focused laser beam is used that enables the high information density required for high-quality digital audio signals. Prototypes were developed by Sony independently in the late 1970s. Although dismissed by Philips Research management as a trivial pursuit, the CD became the primary focus for Philips as the LaserDisc format struggled.
In 1979, Sony and Philips set up a joint task force of engineers to design a new digital audio disc. After a year of experimentation and discussion, the Red Book CD-DA standard was published in 1980. After their commercial release in 1982, compact discs and their players were popular. Despite costing up to $1,000, over 400,000 CD players were sold in the United States between 1983 and 1984. By 1988, CD sales in the United States surpassed those of vinyl LPs, by 1992 CD sales surpassed those of prerecorded music cassette tapes; the success of the compact disc has been credited to the cooperation between Philips and Sony, which together agreed upon and developed compatible hardware. The unified design of the compact disc allowed consumers to purchase any disc or player from any company, allowed the CD to dominate the at-home music market unchallenged. In 1974, Lou Ottens, director of the audio division of Philips, started a small group with the aim to develop an analog optical audio disc with a diameter of 20 cm and a sound quality superior to that of the vinyl record.
However, due to the unsatisfactory performance of the analog format, two Philips research engineers recommended a digital format in March 1974. In 1977, Philips established a laboratory with the mission of creating a digital audio disc; the diameter of Philips's prototype compact disc was set at 11.5 cm, the diagonal of an audio cassette. Heitaro Nakajima, who developed an early digital audio recorder within Japan's national public broadcasting organization NHK in 1970, became general manager of Sony's audio department in 1971, his team developed a digital PCM adaptor audio tape recorder using a Betamax video recorder in 1973. After this, in 1974 the leap to storing digital audio on an optical disc was made. Sony first publicly demonstrated an optical digital audio disc in September 1976. A year in September 1977, Sony showed the press a 30 cm disc that could play 60 minutes of digital audio using MFM modulation. In September 1978, the company demonstrated an optical digital audio disc with a 150-minute playing time, 44,056 Hz sampling rate, 16-bit linear resolution, cross-interleaved error correction code—specifications similar to those settled upon for the standard compact disc format in 1980.
Technical details of Sony's digital audio disc were presented during the 62nd AES Convention, held on 13–16 March 1979, in Brussels. Sony's AES technical paper was published on 1 March 1979. A week on 8 March, Philips publicly demonstrated a prototype of an optical digital audio disc at a press conference called "Philips Introduce Compact Disc" in Eindhoven, Netherlands. Sony executive Norio Ohga CEO and chairman of Sony, Heitaro Nakajima were convinced of the format's commercial potential and pushed further development despite widespread skepticism; as a result, in 1979, Sony and Philips set up a joint task force of engineers to design a new digital audio disc. Led by engineers Kees Schouhamer Immink and Toshitada Doi, the research pushed forward laser and optical disc technology. After a year of experimentation and discussion, the task force produced the Red Book CD-DA standard. First published in 1980, the stand
Photo CD is a system designed by Kodak for digitizing and saving photos onto a CD. Launched in 1992, the discs were designed to hold nearly 100 high quality images, scanned prints and slides using special proprietary encoding. Photo CDs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well, they were intended to play on CD-i players, Photo CD players, any computer with a suitable software. The system failed to gain mass usage among consumers due to its proprietary nature, the decreasing scanner prices, the lack of CD-ROM drives in most home personal computers of the day. Furthermore, Photo CD relied on CRT-based TV sets for home use. However, these were designed for moving pictures, their typical flicker became an issue. The Photo CD system gained a fair level of acceptance among professional photographers due to the low cost of the high quality film scans. Prior to Photo CD, professionals who wished to digitize their film images were forced to pay much higher fees to obtain drum scans of their film negatives and transparencies.
The Kodak Pro Photo CD Master Disc contains 25 images with maximum resolution of 6144 x 4096 pixels. This type is appropriate for 120 film, 4x5, but for small picture film, if highest resolution is required. Separate from the Photo CD format is Kodak's proprietary "Portfolio CD" format, which combines Red Book CD audio and Beige Book PCD with interactive menus and hotspots on PCD images; some standalone Philips Photo/Audio CD players could play Portfolio CDs, Windows player application was available. The Kodak Portfolio CD is not defined in any particular Rainbow Book; the Photo CD system was announced by Kodak in 1990. Photo CD targeted a full range of photographic needs, ranging from consumer level point-and-shoot cameras to high-end professionals using large format 4x5 sheet film; the first Photo CD products, including scanners for processing labs and Photo CD players for consumers, became available in 1992. The project was expected to be a $600 million business by 1997 with $100 million in operational earnings.
Kodak entered into a number of partnerships grow the usage of Photo CD. This included, for example, an arrangement with L. L. Bean in 1992 by which the catalog would be distributed in Photo CD format, an arrangement with Silicon Graphics in 1993 to make all Silicon Graphics image-processing workstations capable of accepting Kodak Photo CD optical disks; these measures, together with the relatively low cost of $3 per image and convenience, made Photo CD the digital imaging solution of choice for many photographers in the mid to late 1990s. By 2000, over 140 Photo CD processing labs in the U. S. were active, with many more outside the U. S. However, by the late 1990s, Photo CD was being eclipsed by alternate formats based on the industry standard JPEG format. In the consumer segment, the Photo CD format's inefficient compression scheme meant that Photo CD files were larger than a JPEG files of similar quality, thus less convenient for transmission across the internet, etc. For example, a 16Base Photo CD image of 5.5 Mb can be encoded as a JPEG image of 2.1 Mb at 80% quality, visually indistinguishable from the original.
When the Photo CD format was designed in the early 1990s, a design goal was to allow low cost playback-to-TV devices. At that time the available technology precluded 2-dimensional compression schemes such as JPEG, but by the late 1990s, advances in microprocessor technology had moved JPEG/PNG compression to well within the range of very low cost consumer electronics. In the professional and advanced amateur segments, Photo CD had been eclipsed by low cost desktop scanners such as those from Nikon and Minolta in the mid range, by drum scanners at the high end. While the pixel resolution of Photo CD was still comparable or better than the alternatives, Photo CD suffered from a number of other disadvantages. Firstly, the Photo CD color space, designed for TV display, is smaller than what can be achieved by a low cost desktop scanner. Secondly, the color rendition of Photo CD images changed over time and with different scanner versions. Thirdly, the dynamic range of scans was lower than for desktop scanners.
Tests at the time indicated that the dmax rating of Photo CD was 2.8-3.0, while available desktop scanners were reaching 4.2, a substantial difference. As a result of this, Photo CD's problems with color rendering, by 2004 the professional segment of the user community had turned against Photo CD. In the retail segment, while Photo CD was relatively popular with consumers, it was an economic failure for processing labs. At the time of its introduction, Kodak claimed that processing costs to labs would be close to $1 per image, which would allow the lab profitably sell at the $3 per image mark; however this promise was never realized resulting in the scanning process being rushed, with a resulting fall in quality. As a result of Photo CD's loss of market share and substantial corporate losses attributed by Kodak Management to its scanning business, Kodak abandoned the format over the period 2001-2004. By 2004, Kodak 4050 Photo CD scanners were being offered for free to anyone that would pay for their removal by more than one processing lab.
This abandonment generated considerable controversy both at the time and subsequently as the Photo CD format's technical specifications have never been released by Kodak. Photo CD remains an quoted example of an “orphan format” and o