MultiLevel Recording (
ML) (also known as M-ary) was a technology originally developed by Optex Corporation and promoted by
CalimetricsCalimetrics was founded in 1994 by Terrence Wong, Michael O'Neill, and Thomas Burke. Based on Dr. Wong and Dr. O'Neill's UC Berkeley research, the company received startup funding of $1.8M from an Advanced Technology Program grant to conduct research and development on pit depth modulated optical...
to increase the storage capacity of optical discs. It failed to establish itself on the market. Through a combination of proprietary media, recorder, reader and player modifications,
CalimetricsCalimetrics was founded in 1994 by Terrence Wong, Michael O'Neill, and Thomas Burke. Based on Dr. Wong and Dr. O'Neill's UC Berkeley research, the company received startup funding of $1.8M from an Advanced Technology Program grant to conduct research and development on pit depth modulated optical...
proposed that ML could increase the capacity of a
CD-ROMCD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback, the 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data. CD-ROMs are popularly used to...
,
CD-RA CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session....
or
CD-RWCompact Disc ReWritable is a rewritable optical disc format. Known as CD-Erasable during its development, CD-RW was introduced in 1997, and was preceded by the never officially released CD-MO in 1988.- Explanation :...
to 2 GB, a single-layer
DVDDVD, also known as Digital Versatile Disc or Digital Video Disc,is an optical disc storage media format, and was founded in 1995. Its main uses are video and data storage...
,
DVD-RDVD-R is a DVD recordable format. A DVD-R type has a storage capacity of 4.71 GB , although the capacity of the original standard developed by Pioneer was 3.95 GB . Both values are significantly larger than the storage capacity of its optical predecessor, the 700 MB CD-R – a DVD-R has 6.4 times...
,
DVD+RDVD+R is a format for optical data storage. It is similar to, but incompatible with, the earlier DVD-R standard. A DVD+R is a write-once optical disc with 4.7 gigabytes of storage, generally used for nonvolatile data storage or video applications....
,
DVD-RWA DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum...
,
DVD+RWDVD+RW is the name of a standard for optical discs: one of several types of DVD, which hold up to about 4.7 GB per disc and are used for storing films, music or...
or
DVD-RAMDVD-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.- Design :There are three competing technologies for...
to 7.1 to 10 GB and a single-layer
Blu-ray DiscBlu-ray Disc is an optical disc storage medium designed to supersede the standard DVD format. Its main uses are for storing high-definition video, PlayStation 3 games, and other data, with up to 25 GB per single layered, and 50 GB per dual layered disc...
(BD) to as much as 60 GB.
MultiLevel Recording (
ML) (also known as M-ary) was a technology originally developed by Optex Corporation and promoted by
CalimetricsCalimetrics was founded in 1994 by Terrence Wong, Michael O'Neill, and Thomas Burke. Based on Dr. Wong and Dr. O'Neill's UC Berkeley research, the company received startup funding of $1.8M from an Advanced Technology Program grant to conduct research and development on pit depth modulated optical...
to increase the storage capacity of optical discs. It failed to establish itself on the market. Through a combination of proprietary media, recorder, reader and player modifications,
CalimetricsCalimetrics was founded in 1994 by Terrence Wong, Michael O'Neill, and Thomas Burke. Based on Dr. Wong and Dr. O'Neill's UC Berkeley research, the company received startup funding of $1.8M from an Advanced Technology Program grant to conduct research and development on pit depth modulated optical...
proposed that ML could increase the capacity of a
CD-ROMCD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback, the 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data. CD-ROMs are popularly used to...
,
CD-RA CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session....
or
CD-RWCompact Disc ReWritable is a rewritable optical disc format. Known as CD-Erasable during its development, CD-RW was introduced in 1997, and was preceded by the never officially released CD-MO in 1988.- Explanation :...
to 2 GB, a single-layer
DVDDVD, also known as Digital Versatile Disc or Digital Video Disc,is an optical disc storage media format, and was founded in 1995. Its main uses are video and data storage...
,
DVD-RDVD-R is a DVD recordable format. A DVD-R type has a storage capacity of 4.71 GB , although the capacity of the original standard developed by Pioneer was 3.95 GB . Both values are significantly larger than the storage capacity of its optical predecessor, the 700 MB CD-R – a DVD-R has 6.4 times...
,
DVD+RDVD+R is a format for optical data storage. It is similar to, but incompatible with, the earlier DVD-R standard. A DVD+R is a write-once optical disc with 4.7 gigabytes of storage, generally used for nonvolatile data storage or video applications....
,
DVD-RWA DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum...
,
DVD+RWDVD+RW is the name of a standard for optical discs: one of several types of DVD, which hold up to about 4.7 GB per disc and are used for storing films, music or...
or
DVD-RAMDVD-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.- Design :There are three competing technologies for...
to 7.1 to 10 GB and a single-layer
Blu-ray DiscBlu-ray Disc is an optical disc storage medium designed to supersede the standard DVD format. Its main uses are for storing high-definition video, PlayStation 3 games, and other data, with up to 25 GB per single layered, and 50 GB per dual layered disc...
(BD) to as much as 60 GB. An optionally integrated
Digital Rights ManagementDigital rights management is a generic term for access control technologies that can be used by hardware manufacturers, publishers, copyright holders and individuals to try to impose limitations on the usage of digital content and devices...
(DRM) system entitled MovieGuard was also suggested. An industry group called the ML Alliance was formed in 2000 to help commercialize ML technology. Members eventually included
CalimetricsCalimetrics was founded in 1994 by Terrence Wong, Michael O'Neill, and Thomas Burke. Based on Dr. Wong and Dr. O'Neill's UC Berkeley research, the company received startup funding of $1.8M from an Advanced Technology Program grant to conduct research and development on pit depth modulated optical...
, TDK, Sanyo Semiconductor,
Plextoris a brand best known for its optical disc recorders. The brand name is used for all products manufactured by the Electronic Equipment Division and Printing Equipment Division of Shinano Kenshi. The brand was formerly known as TEXEL by which name it introduced its first CD-ROM optical disk drive in...
, Matsushita Kotobuki Electronics,
Mitsubishi Chemical Corporation, or MCC, was a Japanese corporation. It merged with Mitsubishi Pharma Corporation to create Mitsubishi Chemical Holdings Corporation.-External links:...
, Verbatim,
TeacThis article refers to the company. For the antioxidant measure, see Trolox equivalent antioxidant activityTEAC Corporation is an electronics company based in Japan...
and Yamaha.
Several 2 GB ML CD-based recorders were developed for release in 2002 (TDK's MLCDRW1000 and Plextor's PX-ML3630), but never came to market. This was largely a business decision influenced by the rapid fall of CD-R/RW prices and the simultaneous rise in popularity of writable DVD technology. Calimetrics went on to work on more advanced DVD and Blu-ray Disc versions of their technology, including a proposal to build a next generation version of
Enhanced Versatile DiscThe Enhanced Versatile Disc is an optical medium-based digital audio/video format, developed to provide a means for playing HDTV content using existing optical media. It was announced on November 18 2003 by China's Xinhua News Agency as a response to the popular DVD-Video format and its licensing...
(EVD). Calimetrics ceased operations in 2004.
Technology
To store information onto a physical surface, the data must be transformed into a series of marks, using a
modulation codeModulation is the process of varying one waveform in relation to another waveform. In telecommunications, modulation is used to convey a message, or a musician may modulate the tone from a musical instrument by varying its volume, timing and pitch. Often a high-frequency sinusoid waveform is used...
. The codes used in most optical disc systems are binary, meaning that resulting surface has only two states: marks and non-marks. The following figure illustrates the
EFMEight-to-fourteen modulation is a data encoding technique used by compact discs and pre-Hi-MD MiniDiscs. EFM and EFMPlus were both invented by Kees A...
code used in CDs and DVDs:
Because the edges are positioned on a grid that is finer than the minimum mark size,
EFMEight-to-fourteen modulation is a data encoding technique used by compact discs and pre-Hi-MD MiniDiscs. EFM and EFMPlus were both invented by Kees A...
achieves about 1.5 bits per minimum-mark, even though it is a binary code.
MultiLevel recording refers to the use of multiple reflectivity values to encode data onto an optical disc. By using more than two levels, more information can be put into the minimum feature size. The following figure illustrates a MultiLevel code (note: colors are used only to represent differences in intensity):
The 8-level code used on the prototype systems is a
convolutional codeIn telecommunication, a convolutional code is a type of error-correcting code in which each m-bit information symbol to be encoded is transformed into an n-bit symbol, where m/n is the code rate and the transformation is a function of the last k information symbols, where k is the constraint...
, storing about 2.5 bits per data cell. By using this code in combination with a smaller mark size and a more efficient error-correction code, the capacity of CD media was tripled. When applied to dual-layer DVD, ML-recording can increase capacity by a factor of 1.9.
MultiLevel optical recording is an example of
basebandIn telecommunications and signal processing, baseband is an adjective that describes signals and systems whose range of frequencies is measured from zero to a maximum bandwidth or highest signal frequency; it is sometimes used as a noun for a band of frequencies starting at zero...
pulse-amplitude modulation-Overview:Pulse-amplitude modulation, acronym PAM, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses....
. While Non-binary, or M-ary, modulation is common in the
telecomTelecommunication is transmission over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, drums, semaphore, flags or heliograph. In modern times, telecommunication typically involves the use of electronic devices such as the telephone,...
industry, the technique was originally developed and patented for optical disc recording at Optex Corporation in the early 1990's (in conjunction with the University of Rochester) for use with their Electron Trapping Optical Media (ETOM). Although simple in principle, implementation of ML was challenging, in large part because data storage
channelsChannel, in communications , refers to the medium used to convey information from a sender to a receiver.- Overview :...
are highly
nonlinearIn mathematics, a nonlinear system is a system which is not linear, that is, a system which does not satisfy the superposition principle, or whose output is not proportional to its input. Less technically, a nonlinear system is any problem where the variable to be solved for cannot be written as a...
. The overall ML-system response is much more sensitive to variations in its individual components (operating temperature, media uniformity, read-head fluctuation, etc.) than a conventional CD/DVD system. To compensate, the ML logical-format devotes a substantial portion of bits (as forward-error correction coding) to enhance robustness against media defects and
signal noiseIn science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information being received at a detector. In communications, it may be deliberate as for instance jamming of a radio or TV signal, but in most cases it...
. ML-drives used sophisticated power-optimization during writing and adaptive equalization during reading.
MultiLevel recording is sometimes confused with
multi-layer storage, in which multiple data surfaces are combined into a single disc. Multi-layer and multiLevel technique can be combined (as in dual-layer ML-DVD ROM), where ML-modulation is applied to each individual layer of the disc.
External links