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Orange Book is the set of specifications created by Philips and Sony to define the optical signal characteristics, physical arrangement, writing methods and testing conditions for CD-R (Orange Book Part II) and CD-RW (Orange Book Part III) discs. First released in 1990, Orange Book originally dealt with only single speed CD-R recording but, with rapid advances since made in hardware and media technology, the specification grew to include CD-RW in 1996. Higher writing speeds continue to be incorporated as the industry evolves.
Orange Book organizes CD-R and CD-RW discs into various sections serving distinct purposes. The Information Area is most fundamental and consists of a shallow spiral groove (pregroove) extending from the discs� inside to outside diameter. Encoded in the structure of this pregroove are speed control and Absolute Time In Pregroove (ATIP) time code information as well as other parameters critical for recorders to correctly write a disc. Several regions within this pregroove are reserved exclusively for recorder use.
The first is the Power Calibration Area (PCA), located in the inner portion of the disc, which is employed while determining the correct power level for the writing laser. Due to physical and practical design limitations on rotational velocity it is, generally speaking, not possible to conduct power calibrations at the inner diameter of the disc at speeds above 16x. A process of extrapolation is therefore used to determine suitable writing power for those higher speeds. Recently, Orange Book has designated the addition of another PCA located in the Lead-Out Area at the outer portion of the disc to provide the space necessary to conduct actual high speed write power calibrations.
Following the first PCA is the Program Memory Area (PMA) which is used as intermediate storage to record track information for all sessions written to the disc. Typically, the PMA is first followed by the Lead-In Area, containing table of contents information, followed by the Program Area which holds the written data tracks and finally the Lead-Out Area which indicates to a reading device that the end of the data has been reached.
Multisession recording allows additional data to be written to a previously partially recorded CD-R or CD-RW disc. Each session on the multisession disc has its own Lead-In Area, Program Area and Lead-Out Area and may be connected to other sessions to function as a single volume (linked) or operate independently (multi-volume). In addition to being written by a recorder the first session of a multisession disc can be, alternatively, prerecorded (stamped) at the factory.
Fixation is the process of completing a CD-R or CD-RW disc session by writing Lead-In (table of contents) and Lead-Out information. Once a disc is fixated it can then be played back in CD and DVD-ROM drives and recorders and consumer electronics devices compatible with the particular disc type and format. It is also possible to record additional information later to create a multisession disc. Finalization, on the other hand, completely closes the disc so no further material can be added.
CD-R and CD-R/RW recorders employ several different writing modes including Disc-At-Once (DAO), Track-At-Once (TAO), Session-At-Once (SAO), and packet writing. Be aware that not all recorders and software support all writing modes. If in doubt, consult with the product manufacturer.
During DAO recording the Lead-In Area, Program Area and Lead-Out Area of a CD-R or CD-RW disc are consecutively written in a single uninterrupted operation. DAO recording is only possible using a blank disc and, after recording is completed, no additional information can be written. Typically, DAO is used to write CD audio, CD-Text and discs destined for mass replication.
In contrast to DAO, TAO operates by turning the writing laser on and off at the beginning and end of each track and writes the Program Area of a disc before its Lead-In and Lead-Out Areas. It is possible to use a recorder to read from (or write additional tracks to) a TAO disc before a session is fixated. All TAO discs contain 2 to 3 second gaps between tracks (run-in, run-out and link blocks) but some recorders have the ability to vary the size of the gaps.
SAO is much like DAO in that the Lead-In Area, Program Area and Lead-Out Area are consecutively written in a single uninterrupted operation. However, the first session is not finalized so additional sessions can be added. Typically, SAO is used to write
CD Extra (Enhanced Music CD) discs where the first session contains one or multiple audio tracks and the second session consists of multimedia computer data.
Packet writing records variable (CD-R) or fixed (CD-RW) sized chunks or �packets� of data to the disc for as many times as is needed to complete the writing of the user�s files. In the case of a CD-R disc (which is not erasable) data may be added incrementally until the disc becomes full. CD-RW discs, on the other hand, are completely rewritable and thus are a little different from their CD-R cousins in that files can be added and deleted as needed.
The ISO 9660 standard was introduced in 1988 and is the most widely used file format for data (CD-ROM) discs. ISO 9660 defines a common logical format for files and directories so discs written to ISO 9660 specifications can be read by a wide array of computer operating systems (MS-DOS, Windows, Mac OS, UNIX, etc.) as well as consumer electronics devices. Due to the vast differences which exist among native file systems ISO 9660 takes a lowest common denominator approach resulting in a variety of restrictions upon the nature and attributes of files and directories. Three levels of interchange define these restrictions with level one being the most constraining and level three is the least (at the cost of compatibility with some operating systems). Various protocols are available to extend ISO 9660 to accommodate file system features specific to individual operating systems (longer file names, deeper directory structures, more character types, etc.) while preserving ISO 9660 compatibility with other platforms. These protocols include Joliet (Windows 95 and higher), Apple Extensions (Mac OS) and Rock Ridge (UNIX).
The Universal Disc Format (UDF) specification was first released by OSTA in 1995 and is designed to be a common logical file system for all removable optical storage media. Over the years various updates to UDF have been introduced to add new capabilities. For example, UDF 1.02 is the standard file system used for prerecorded and recordable DVD discs while UDF 1.5 is commonly employed for packet writing CD-R and CD-RW media. Most recently, UDF 2.0 has added full support for Windows NT, enhanced data security and improved CD-R functions while defining backward read capabilities between discs created with the new UDF 2.0 format and discs created with earlier versions of UDF.
The term �hybrid� is popularly used to describe several different types of discs. The first kind of hybrid disc is one that contains multiple file systems, such as ISO 9660 and HFS (Mac OS). A second type of hybrid is a CD that contains applications designed to interact with the Internet so static data resides on the disc and live information is downloaded as needed from the Web. These discs are sometimes called �connected CDs.� A third kind of hybrid is defined by Orange Book as a CD-R or CD-RW disc with a prerecorded (stamped) first session with the ability to potentially hold additional written sessions.
Running Optimum Power Control (Running OPC) is a special technique used in many newer CD-R and CD-R/RW recorders that monitors and maintains the quality of the disc writing and ensures the accuracy of all the marks and lands lengths across the disc. The term Running OPC actually describes the general process that may be known by several trade names. Some differences in execution may be present to give some of these implementations competitive advantages over others.
RECORDING HARDWARE
All CD-R and CD-R/RW recorders write CD-R discs but only CD-R/RW recorders write both CD-R and CD-RW discs. Many DVD recorders also come combined with CD-R and CD-RW writing functions but be aware that there are exceptions. If in doubt, consult with the hardware manufacturer.
Several manufacturers offer consumer and professional audio CD recorders that connect, like cassette decks, to conventional stereo systems. Typically, they will record to CD-R or CD-R and CD-RW discs from either digital (CD, DAT, MD, etc.) or analog (cassette, vinyl record, radio, etc.) sources.
Manufacturers typically use a sequence of two, three or four numbers to express the maximum writing and reading speeds of a recorder. The generally accepted industry convention for a CD-R recorder has been for the first figure to indicate CD-R writing speed followed by CD reading speed for CD-R and prerecorded (pressed) data CDs. For a CD-R/RW recorder the first number usually indicates CD-R writing speed followed by CD-RW writing speed and then by the CD reading speed. In the case of a combination recorder a fourth number is included to indicate DVD reading speed. As examples, 8x12 usually means 8x CD-R write and 12x CD read while 48x12x48 typically indicates 48x CD-R write, 12x CD-RW write and 48x CD read. And for a combination recorder 24x10x40x12 denotes 24x CD-R write, 10x CD-RW write, 40x CD read, and 12x DVD read.
Whether for PC, Mac or UNIX computers in desktop, laptop or notebook form, CD-R and CD-R/RW recorders are available in a wide variety of configurations to suit most needs. Several industry standard interfaces are available including SCSI, EIDE/ATAPI, Parallel, USB and IEEE 1394 for either internal or external recorder connection.
The Enhanced Integrated Drive Electronics/ATA Packet Interface (EIDE/ATAPI) is the most popular method for connecting CD and DVD-ROM drives and hard disks as well as CD-R and CD-R/RW recorders to a computer. Since most computers already have EIDE/ATAPI built-into their motherboards no additional interface card is necessary. These devices are normally installed internally but many external recorders are actually EIDE/ATAPI models that use bridge technology to convert them to SCSI, USB or IEEE 1394 interfaces.
The Small Computer Systems Interface (SCSI) or “scuzzy” interface is a high performance and flexible method of connecting to a computer many peripherals including scanners, CD and DVD-ROM and hard drives as well as CD-R and CD-R/RW recorders. In addition to long cable lengths, SCSI allows for both internal and external attachments. Some computers already have SCSI built-into their motherboards, but, more often than not, a SCSI interface card is required. Depending upon the specific product, a SCSI card may or may not be included with the CD-R/RW recorder bundle.
CD-R/RW recorders that make use of a parallel interface connect to the computer using the same parallel port used by a printer and can only be installed externally. Depending upon the product, some recorders have pass-through arrangements allowing both a printer and recorder to be connected to the computer at the same time.
The Universal Serial Bus (USB) is used to connect many types of peripherals to a computer including joysticks, mice, keyboards, printers, scanners and external CD-R and CD-R/RW recorders. Since USB is a plug and play interface computers do not have to be rebooted when a recorder is attached as these devices are automatically recognized by the system. And USB has been updated several times to accommodate the demands of increasingly faster peripherals. USB 1.1 interfaces are built into the motherboards of many systems and generally permit up to 4x CD-R/RW writing and 6x reading speeds. USB version 2.0 is an updated version of the specification allowing greater performance but typically requires an additional interface card. Most USB 2.0 CD-R/RW recorders are backward compatible and can operate at reduced speed when connected to older USB 1.1 systems.
Popularly known by trade names such as FireWire and i.LINK, IEEE 1394 is a high performance plug and play interface commonly used to connect computers to external hard disk drives and CD-R and CD-R/RW recorders as well as consumer electronics devices like digital camcorders, televisions and game consoles. IEEE 1394 interfaces come standard on many Macintosh systems and on some brands of PCs but, more often than not, an interface card is required.
An important point to remember about CD-R and CD-RW recording is that information must be written to a blank disc in a continuous stream. To help smooth out the flow in the data transfer rate from the computer, the recorder employs a memory buffer which, like a reservoir storing water for use when it is needed, caches data for when it is required by the recorder. As with a water reservoir, the key is to always have enough data in the buffer to satisfy the demands of the recorder, even if, from time to time, the computer can’t supply the needed amount of information. If the buffer runs dry (a “buffer underrun”) the disc is ruined.
Most current computer recorders incorporate advanced buffer underrun protection technology to eliminate buffer underruns but for units not so equipped there are a variety of common sense techniques that can be used to help minimize the possibility. These include ensuring that the recorder and writing software are properly configured, defragmenting the operating system and data source hard disk partitions, disconnecting from any networks, closing all other programs and disabling background tasks such as power managers and anti-virus software. In more stubborn cases additional measures to be considered include reducing writing speed as well as enabling the recording software to build a temporary image on the hard disk drive before recording.
In order to keep pace with the demands of ultra speed writing, recorder manufacturers have created new technologies for preventing buffer underruns. A recent innovation now known by a multitude of different trade names, buffer underrun protection utilizes a combination of recorder hardware, firmware and writing software to accomplish its task.
Buffer underrun protection functions by constantly monitoring the amount of data in the recorder’s buffer during the writing of a disc and suspends recording if the amount available falls below a predetermined threshold. Once the buffer again accumulates sufficient data the recorder resumes writing precisely where it left off. Obviously, it’s critical to leave as small a gap as possible between the previous and newly recorded sections so as to avoid producing an unreadable segment on the disc. Generally speaking, the gap length has been found to be well within the error correction capabilities of CD and DVD-ROM drives and players. As the technology matures the gap will continue to shrink.
RECORDING SOFTWARE
The two main types of software needed to operate CD-R and CD-R/RW recorders, namely packet writing software and CD recording software (sometimes called premastering software), are available for most major operating systems. The majority of CD-R and CD-R/RW recorders include either one or both types as part of their purchase bundles. Be aware, however, that software from competing publishers may offer a different range of features. In addition, some current operating systems and standalone application software have built-in CD-R and CD-RW recording capabilities.
Unlike many removable storage solutions that are restricted to just housing and retrieving data, CD-R and CD-R/RW recorders are also used as powerful multimedia devices. In addition to providing the means to store, backup and distribute data on CD-R and CD-RW discs, many CD recording software packages also include the tools necessary to write or edit different content on CDs such as music, photos and video.
Taking the form of standalone applications, many recording software packages have the capability to create discs in different physical formats (eg. data, audio, video, hybrid, etc.) using various file systems (eg. UDF, ISO 9660, HFS, etc.) and support different file naming conventions (eg. Joliet, Rock Ridge, Apple extensions, etc.). Some can actually clean up clicks, pops, scratches and hiss from old music LPs or cassettes and lay out and print labels and jewel case inserts to personalize and identify discs after they are written. Depending upon the package, other capabilities may include the ability to duplicate CDs, assemble Red Book CD-DA or compressed digital audio compilation CDs a track at a time from different sources and even create photo and video albums.
Packet writing software installs at the driver level and makes a CD-R or CD-R/RW recorder seem to the user as just another removable drive. Appearing the same as a floppy or hard disk, users write files to a CD-R or CD-RW disc by simply dragging and dropping the files over the recorder’s icon or saving from within an application.
As with all removable storage systems, the first step in operating a CD-R or CD-R/RW recorder using packet writing software is to initialize the disc to prepare it to receive the user’s data. After inserting a blank disc into the recorder the user is prompted by the computer to initialize the disc which is then ready to go after an automatic formatting procedure. Some products conduct background formatting where the disc is available to write shortly after initiating the process but others require formatting to complete before data can be written.
Packet writing records variable (CD-R) or fixed (CD-RW) sized chunks or “packets” of data to the disc for as many times as is needed to complete the writing of the user’s files. In the case of a CD-R disc (which is not erasable) data may be added incrementally until the disc becomes full. CD-RW discs, on the other hand, are completely rewritable and thus are a little different from their CD-R cousins in that files can be added and deleted as needed. Typically, packet writing software records CD-R and CD-RW discs in OSTA’s Universal Disc Format (UDF).
After being formatted for packet writing use the storage capacity of CD-R and CD-RW discs is somewhat less than their unprepared state. For example, a 74 minute/650 MB (12 cm) CD-R disc has an initial formatted capacity of roughly 620 MB while an equivalent CD-RW disc stores approximately 530 MB after being formatted for random rewriting. Due to increased defect management overhead, a Mount Rainier formatted CD-RW disc is able to store roughly 30 MB less than its conventionally packet written counterpart.
Generally speaking, it is possible to format a CD-RW disc using one publisher’s packet writing software and write to the same disc using software offered from a different publisher. However, once data has been written to the disc only the software that was used to write the information can be used to append or rewrite other data. Greater writing interchangeability for CD-RW discs is, however, one of the primary goals of the new Mount Rainier format. It is advisable to consult with the appropriate software publisher for specific compatibility details.
The Mount Rainier specification was developed in 2001 to provide the framework necessary for computer operating systems to seamlessly rewrite data CD-RW discs in a drag and drop fashion without the use of additional drivers or software. Through enhancements over the abilities of conventional packet writing software, including background formatting, recorder-based defect management, improved interchangeability and greater ease of use, Mount Rainier’s goal is to make 3.5” floppy diskettes obsolete by replacing them with CD-RW discs for everyday data storage and interchange.
Mount Rainier formatted CD-RW discs are rewritten on Mount Rainier-enabled CD-R/RW recorders. Since this specification is a recent innovation it is supported by only some of the latest recorders but it is expected that, over time, an increasing number of new units will incorporate Mount Rainier capability. In cases where the operating system being used does not offer Mount Rainier functions it will be necessary to employ additional software to format and rewrite discs. Typically, this comes as modified conventional packet writing software to allow the rewriting of Mount Rainier formatted CD-RW discs.
Mount Rainier formatted CD-RW discs are read on MultiRead-compliant CD-ROM drives, CD-R/RW recorders and MultiRead-compliant DVD-ROM drives and recorders. In situations where the operating system used does not offer Mount Rainier functions it is necessary to employ an additional software driver to read the discs. It is therefore advisable to consult with the appropriate hardware manufacturers and software publishers to verify the specific capabilities of your recorder, operating system and writing software.
RECORDING SPEED
The amount of time taken to write a disc depends upon the speed of the recorder, the writing method used by the recorder and the amount of information required to be written. Recording speed is measured the same as the reading speed of ordinary CD-ROM drives and players. At single speed (1x) a recorder writes 150 KB (153,600 bytes) of data (CD-ROM Mode 1) per second and at a multiple of that figure at each speed increment above 1x.
CD Read and Write Average Data Transfer Rates
(transfer rates indicated in bytes)
Read/Write |
Audio |
CD-ROM
Mode 1 |
CD-ROM
Mode 2 |
CD-i/XA
Form 1 |
CD-i/XA
Form 2 |
|
|
|
|
|
|
Speed (CLV) |
(2,352 Bytes/Block) |
(2,048 Bytes/Block) |
(2,336 Bytes/Block) |
(2,048 Bytes/Block) |
(2,324 Bytes/Block) |
|
|
|
|
|
|
1x |
176,000 |
153,600 |
175,200 |
153,600 |
174,300 |
2x |
352,800 |
307,200 |
350,400 |
307,200 |
348,600 |
4x |
705,600 |
614,400 |
700,800 |
614,400 |
697,200 |
6x |
1,058,400 |
921,600 |
1,051,200 |
921,600 |
1,045,800 |
8x |
1,411,200 |
1,228,800 |
1,401,600 |
1,228,800 |
1,394,400 |
12x |
2,112,000 |
1,843,200 |
2,102,400 |
1,843,200 |
2,091,600 |
16x |
2,816,000 |
2,457,600 |
2,803,200 |
2,457,600 |
2,788,800 |
20x |
3,520,000 |
3,072,000 |
3,504,000 |
3,072,000 |
3,486,000 |
As the market for CD-R and CD-RW products came into its own writing speed accelerated due to rapid advances made in hardware and media technology. One breakthrough came in writing modes which permitted recorders to reliably operate beyond 20x speed. Available units now employ a variety of writing modes including Constant Linear Velocity (CLV), Zone Constant Linear Velocity (ZCLV), Partial Constant Angular Velocity (PCAV) and Constant Angular Velocity (CAV).
CDs were originally designed for consumer audio applications and initially operated using a CLV mode to maintain a constant data transfer rate across the entire disc. The CLV mode sets the disc’s rotation at 500 RPM decreasing to 200 RPM (1x CLV) as the optical head of the player or recorder reads or writes from the inner to outer diameter. Since the entire disc is written at a uniform transfer rate it takes, for example, roughly 76 minutes to complete a full 74 minute/650 MB disc at 1x CLV. As recording speed increases the transfer rate increases correspondingly so that at 8x CLV writing an entire disc takes 9 minutes and at 16x 5 minutes. Recording time as well is directly related to the amount of information to be written so partial discs are completed in proportionally less time. But writing at higher speeds requires rotating the disc faster and faster (eg. 10,000 to 4,000 RPM at 20x CLV which places escalating physical demands upon both media and hardware. Manufacturers have met this challenge by moving beyond the original CLV mode to obtain even higher performance.
In contrast to CLV which maintains a constant data transfer rate throughout the recording process, ZCLV divides the disc into regions or zones and employs progressively faster CLV writing speeds in each. For example, a 40x ZCLV recorder might write the first 10 minutes of the disc at 20x CLV, the next 15 minutes at 24x CLV, the following 30 minutes at 32x CLV and the remainder at 40x CLV speed.
Some recorders make use of the PCAV mode which spins the disc at a lower fixed RPM when the optical head is writing near the inner diameter but then shifts to CLV part way further out on the disc. As a result, the data transfer rate progressively increases until a predetermined point is reached and thereafter remains constant. For example, a 24x PCAV recorder might accelerate from 18x to 24x speed over the first 14 minutes of the disc then maintain 24x CLV writing for the remainder of the disc.
The CAV mode spins the disc at a constant RPM throughout the entire writing process. Consequently, the data transfer rate continuously increases as the optical head writes from the inner to outer diameter of the disc. For example, a 48x CAV recorder might begin writing at 22x at the inner diameter of the disc accelerating to 48x by the outer diameter of the disc.
CD-RW media present additional problems in that it is not possible for one kind of CD-RW disc to support all recording speeds. Low speed discs are compatible with all CD-RW recorders and can only be written from 1x to 4x speeds. High speed discs, on the other hand, can be written from 4x to 10x but only on recorders bearing the high speed CD-RW logo.
The speed at which a disc is written has nothing to do with the speed at which it can be read back in a recorder, CD-ROM or DVD-ROM drive.
Recorder and media manufacturers carefully tune their products to operate with each other across a wide range of speeds. As a result, equally high quality CDs are created when recording at almost all speeds. However, 1x presents a minor exception. Generally speaking, the physics and chemistry involved in the CD recording process seem to produce more consistent and readable marks in CD-R discs at 2x and greater speeds.
In order to accommodate progressively higher recording speeds CD-R disc design and manufacturing has continued to evolve. Consequently, reliable operation is best achieved by following disc manufacturers’ guidance with respect to the range of writing speeds formally supported by their respective discs, while acknowledging that this can change as recording specifications change. Additionally, new media companies and products continually enter the market and some recorder companies may test particular brands of discs more extensively than others. Thus it may be advisable to inquire of the recorder manufacturer for specific media recommendations.
CD writing speed can be set at an appropriate level manually in all premastering software to correspond with the recommendations of the recorder and disc manufacturers. Beyond this, some of the latest recorders also employ systems to actively monitor the writing process and automatically adjust recording speed in order to achieve the optimum
PHYSICAL COMPATIBILITY
Once written, CD-R discs closely mimic the optical characteristics of prerecorded (pressed) CDs. As a result, they can be read on almost any computer CD-ROM drive, CD-R or CD-R/RW recorder or MultiRead-compliant DVD-ROM drive or recorder. Additionally, CD-R discs are compatible with most consumer electronics devices including portable, car and set-top CD audio players and MultiPlay-compliant DVD-Video players and recorders. All DVD devices that read CD-R discs do not necessarily display the MultiRead or MultiPlay logos. If in doubt, consult with the hardware manufacturer.
Written CD-RW discs have slightly different optical characteristics (lower reflectivity and signal modulation) than prerecorded (pressed) and written CD-R discs and therefore are not as widely compatible. They can be read only on MultiRead-compliant CD-ROM drives, CD-R/RW recorders and MultiRead-compliant DVD-ROM drives and recorders. CD-RW discs are, in addition, compatible with some consumer electronics devices including MultiPlay-compliant portable, car and set-top CD audio players and MultiPlay-compliant DVD-Video players and recorders. Again, all CD and DVD devices that read CD-RW discs do not necessarily display the MultiRead or MultiPlay logos. If in doubt, consult with the hardware manufacturer.
The MultiRead specification was created by OSTA in 1997 to provide hardware manufacturers with the requirements necessary to make CD-ROM drives and recorders read CD-RW discs. MultiRead also bridges the differences between CD and DVD technologies and provides the framework for DVD-ROM drives and recorders to read CD-R and CD-RW discs. Specifically, MultiRead requires that compatible drives read Red Book CD audio and CD-ROM information contained on prerecorded (pressed), CD-R and CD-RW discs.
Examples of Discs Readable by
MultiRead-Compliant Drives and Recorders
Type of Disc |
CD-ROM Drive |
CD-R Recorder |
CD-R/RW Recorder |
DVD-ROM Recorder |
DVD-R/-RW Recorder |
DVD-RAM Recorder |
DVD+R/+RW Recorder |
|
|
|
|
|
|
|
|
CD-DA disc |
yes |
yes |
yes |
yes |
yes |
yes |
yes |
CD-ROM disc |
yes |
yes |
yes |
yes |
yes |
yes |
yes |
CD-R disc |
yes |
yes |
yes |
yes |
yes |
yes |
yes |
CD-RW disc |
yes |
yes |
yes |
yes |
yes |
yes |
yes |
The MultiPlay specification was created by OSTA in 2000 to provide hardware manufacturers with the requirements necessary to make CD and DVD consumer electronics devices play CD-R and CD-RW discs. Specifically, MultiPlay requires that all compatible devices play prerecorded (pressed), CD-R and CD-RW discs in Red Book audio format. As well, devices with CD-Text and VideoCD capabilities must also play these formats when written on CD-R and CD-RW discs.
DVD format specifications deal with elements of disc design and not the hardware that reads them. As a result, DVD device manufacturers are free to incorporate whatever features they like into their products, including deciding which types of discs are supported. Consumer demand and cost considerations are taken into account by manufacturers who then construct their products and marketing accordingly.
In addition to these market forces a number of technical issues come into play. Despite appearances to the contrary, a CD and a DVD are distinctively different physically from each other. For example, a DVD disc uses a substrate half as thick as does a CD (0.6 mm vs. 1.2 mm) as well as smaller pit and lands and has less distance between the coils of the data track. A DVD is also read using a shorter wavelength laser (650 nm red vs. 780 nm infra-red) through an optical lens with a larger numerical aperture (0.60 vs. 0.45). Thus, DVD devices which also read prerecorded (pressed) CDs employ a number of tactics to accommodate these differences. However, a CD-R disc has its own unique construction so reading it requires additional hardware components.
Unlike the molded plastic pits of a prerecorded disc the optical responses of the organic dyes used in the recording layer of a CD-R disc are carefully designed to function in the 780 nm range used by CD drives and recorders. Consequently, when a CD-R disc is read using the shorter 650 nm DVD laser wavelength the signals returned from the disc are greatly diminished and may not be read reliably. DVD devices that are designed to read DVD and CD-R discs (such as those compliant with MultiRead and MultiPlay specifications) compensate for this problem by incorporating dual laser optical pickups to generate both 650 nm and 780 nm wavelengths.
A CD-RW disc is a little different. The optical response of the phase change material used in its recording layer is not as wavelength dependent as organic dye in a CD-R and can be read using a 650 nm laser. However, because a CD-RW disc has relatively low reflectivity and signal modulation the optical systems of some DVD devices may not be sensitive enough to read it.
DISC SIZE AND CAPACITY
CD-R and CD-RW discs come in standard 12 cm (120 mm) and 8 cm (80 mm) sizes. The most popular is the larger 12 cm type which has the same physical dimension as most commercial audio CDs and computer software CD-ROMs. 8 cm discs are less common but, thanks to their smaller size, are gaining popularity for use in consumer electronic devices such as portable compressed digital audio players, digital still image cameras and data storage products like miniature CD recorders.
Beyond the conventional 8 cm and 12 cm sizes some manufacturers offer discs shaped like business and credit cards or in other novelty forms. These do not conform with Orange Book specifications and, as a result, may not write and play back in all recorders or reading devices. Following manufacturer instructions is always the best course.
Manufacturers commonly express disc capacity in terms of how much Red Book digital audio (in minutes) and computer data (in megabytes) a disc can contain. Historically, 63 minute/550 MB (12 cm) and 18 minute/158 MB (8 cm) discs were once available but are now rendered obsolete by advances in recording technology. Currently, 74 minute/650 MB, 80 minute/700 MB (12 cm) and 21 minute/185 MB (8 cm) discs are the market standards.
A few media manufacturers have recently introduced 34 minute/300 MB (8 cm), 90 minute/790 MB and 99 minute/870 MB (12 cm) CD-R discs. To achieve these higher capacities such discs do not conform to Orange Book specifications and, as a result, may not write in all recorders, be accessible to all software or readable in all players and drives. Using 34, 90 and 99 minute CD-R discs is therefore not recommended.
The amount of information that can be written is determined by the disc’s recording capacity as well as the physical and logical formats used.
Each of the five main CD physical formats devotes a different amount of space to user data (audio = 2,352 bytes/block, CD-ROM Mode 1 = 2,048 bytes/block, CD-ROM Mode 2 = 2,336/bytes/block, XA Form 1 = 2,048 bytes/block, XA Form 2 = 2,324 bytes/block). For any given data format disc capacity can be calculated by multiplying the appropriate user data area size by the CD data transfer rate of 75 blocks per second by 60 seconds by the minute size of disc. For example, a 80 minute disc written in CD-ROM Mode 1 format: user data area of 2048 bytes/block x 75 blocks/second = 153,600 bytes/second x 60 seconds = 9,216,000 bytes/minute x 80 minutes = 737,280,000 bytes. This rounds to roughly 700 MB (dividing by 1,024 to convert into KB and again by 1,024 to convert into MB). It should be noted, however, that in the real world capacity can vary slightly among discs from different media manufacturers.
For discs written with computer data the logical format used also consumes space available for user information. For example, the overhead for the first session of a multisession disc consumes 22 MB of space and each subsequent session thereafter uses 13 MB. And in the case of CD-RW discs which are formatted for random packet-writing, usable capacity is reduced by roughly 23%.
CD-R and CD-RW Disc Capacities
(capacities indicated in bytes)
Disc
Size |
Playing
Time |
Audio
(2,352 Bytes/Block) |
CD-ROM
Mode 1
(2,048 Bytes/Block) |
CD-ROM
Mode 2
(2,336 Bytes/Block) |
CD-i/XA
Form 1
(2,048 Bytes/Block) |
CD-i/XA
Form 2
(2,324 Bytes/Block) |
|
|
|
|
|
|
|
8 cm |
18 min |
190,512,000 |
165,888,000 |
189,216,000 |
165,888,000 |
188,244,000 |
8 cm |
21 min |
222,264,000 |
193,536,000 |
220,752,000 |
193,536,000 |
219,618,000 |
12 cm |
63 min |
666,792,000 |
580,608,000 |
662,256,000 |
580,608,000 |
658,854,000 |
12 cm |
74 min |
783,216,000 |
681,984,000 |
777,888,000 |
681,984,000 |
773,892,000 |
12 cm |
80 min |
846,720,000 |
737,280,000 |
840,960,000 |
737,280,000 |
836,640,000 |
The only meaningful difference between most 74 and 80 minute discs is their storage capacity. Typically, this increase in usable space is achieved by tightening the coils of the pregroove (track pitch). This allows the disc to accommodate a longer pregroove and therefore a larger recordable area.
Originally, 80 minute discs were specialized products for use in audio premastering studios but now have become commonplace and compatible with most software, recorders, readers and players. In some instances, however, older recorders and premastering software must be upgraded to accommodate 80 minute discs. It is, therefore, advisable to check with the manufacturers of your products and ensure that the latest versions of software and firmware are being used.
Overburning (sometimes called oversizing) is the ability to write beyond the manufacturer’s declared capacity on a CD-R or CD-RW disc. This is accomplished by using the disc’s Lead-Out Area (reserved to indicate to a reading device that the end of the data has been reached) to store the additional user information. Although some recorders and premastering software packages have the ability to overburn a disc the practice is not permitted by Orange Book standards. Overburning might affect product warranties and result in lost data so it is not recommended.
AUDIO RECORDING
What is the Red Book?
Red Book is the set of specifications created by Philips and Sony to define the essential parameters for Compact Disc-Digital Audio (CD-DA). First released in 1980, Red Book has been adopted an international standard (IEC 60908:1999, Audio Recording — compact disc digital audio system) and forms the foundation for all other compact disc standards.
What types of audio CDs can CD-R and CD-R/RW recorders write?
CDs were originally designed for audio so it’s only natural that CD-R and CD-R/RW recorders write discs in the official Compact Disc-Digital Audio (CD-DA) Red Book format for use in any CD audio compatible player. Just like their mass produced prerecorded (pressed) cousins, CD-R and CD-RW discs can hold up to 80 minutes of CD quality audio (44.1 Khz, 16 bit) using as many as 99 separate tracks. In addition to Red Book discs, recorders also write compressed digital audio CDs which, instead of holding conventional tracks, contain MP3, WMA or other compressed audio files. Depending upon the scheme used, one compressed CD-R or CD-RW disc holds as much as ten to twenty ordinary audio CDs and can be played back in devices enhanced for compressed digital audio listening such as compatible computers, personal, home and car CD players as well as many DVD-Video players.
What types of material can be used as sources for audio CD recording?
Depending upon the capabilities of the recorders and software used, CD-R and CD-RW audio discs can be written from either digital or analog sources. Digital material such as existing MP3 files or CDs are conveniently read directly from the hard drive, recorder or from a separate CD or DVD-ROM drive. To record analog sources such as LP records, cassette tapes, microphone or radio tuner inputs connected to a home stereo, signals are first digitized through the computer’s sound card.
Digital
Digital audio material comes in many forms including compressed and uncompressed computer files such as MP3s, WMAs and WAVs, Compact Discs (CD), MiniDiscs (MD), Digital Audio Tapes (DAT), Digital Compact Cassettes (DCC) and Alesis ADAT. How they are handled by the computer for writing to CD varies depending upon the capabilities the individual recording system.
Digital Files
A popular way to create audio discs is to use uncompressed (WAV, PCM, etc.) and compressed (MP3, WMA, etc.) computer files as the recording sources. When producing a compressed digital audio CD these files are written to disc just as they come and, depending upon the recording software used, may be accompanied by MultiAudio or other navigational information. In the case of a Red Book audio CD, compressed files must first be uncompressed and translated into the correct format before recording. Historically, this had to be accomplished manually but most recording software now performs the conversion process automatically during the writing process. As with any audio recording it’s important to remember that the sound quality of a written disc will be no better than the source material used. Higher resolution digital audio files obviously will produce better results.
CD
Recording CD to CD is much simpler than recording from analog sources since most CD and DVD-ROM drives are capable of transferring audio directly (Digital Audio Extraction) without the necessity of converting from analog to digital. As a result, CDs can often be recorded disc to disc using a CD or DVD-ROM drive as the audio source. Where a suitable drive is not available the recorder itself can be used as the audio source. In this case, the audio is read using the recorder and stored temporarily on the computer’s hard drive until written out again.
DAT, MD, DCC, ADAT
Although the contents of DATs, MDs, DCCs and ADATs are already in digital form, most computers lack the proper connections for directly importing digital material. As a result the analog outputs from the source must be connected to the computer’s sound card and the audio re-digitized. Since there is always a loss of quality in the conversion process, some manufacturers offer special sound cards that connect to the digital outputs of the source deck to transfer the audio to the computer while keeping it in quality digital form.
Analog
Analog audio equipment such as LP record players, cassette tape recorders, microphones and radio tuners use continuous electrical signals of varying voltages to record and play sound. Computers, on the other hand operate, in the digital world where everything is represented in binary form. Thus, before the computer can manipulate or record analog audio sources to a hard drive or a CD-R/RW disc, the sounds must be converted into digital form through the computer’s sound card. Higher quality sound cards will produce better results but most cards are capable of recording at the 44.1 kHz frequency, 16 bit resolution used by audio CDs. Some recording software automates the conversion and writing processes into a few simple steps by performing time saving tasks such as detecting the silences between songs to automatically split the music into separate tracks.
What is MultiAudio?
The MultiAudio specification was created by OSTA in 2001 to provide a standardized structure for compressed digital audio files (MP3, WMA, etc.) written onto removable optical media, such as CD-R and CD-RW discs. This uniformity allows these discs to be played back in the same way on any compatible device including MultiAudio-compliant computer software media players and consumer electronics devices such as CD and DVD audio and video players. To accomplish this goal MultiAudio requires that, in addition to compressed digital audio files, an appropriately formatted disc also must contain a defined table of contents which the playing device will use for file navigation. In addition, the specification allows playlists to be created to organize material so it can be accessed by categories such as genre, album, artist or even in custom groupings created by the user. MultiAudio formatted discs are created by standard recording software packages and CD-R/RW recording-enabled audio jukebox applications which support the MultiAudio specification. Written discs can then be played back in MultiAudio compliant devices and even in compressed digital audio units not supporting the specification, albeit in a more limited fashion. Since MultiAudio is simply an organizing system it’s important to remember that the types of discs and specific compressed digital audio file formats supported depend upon the individual capabilities of the particular devices or software employed.
Can consumer compact disc audio recorders write to any CD-R or CD-RW media or are special discs required?
Even though general purpose CD-R and CD-RW discs and their consumer audio versions appear for all practical purposes identical, only blank media bearing the “Compact Disc Digital Audio Recordable” (CD-DA Recordable) and “Compact Disc Digital Audio Rewritable” (CD-DA Rewritable) logos can be written in consumer audio recorders. The reason for this restriction is to comply with international copyright agreements. A special Disc Application Code present in the ATIP information of a CD-DA Recordable/Rewritable disc’s pregroove wobble identifies it specifically for audio use. Consumer audio recorders are programmed to reject discs not containing the correct code. By adopting this safeguard various countries and other authorizing jurisdictions may selectively apply copyright levies to the price of blank discs intended for consumer audio use while exempting those destined for computer or professional applications.
Does using lower CD-R recording speeds and lower capacity media produce better sounding discs?
High speed CD-R writing often creates discs with low I3 and I11 signal amplitudes (optical signals generated from the smallest and largest marks) and 80 minute discs achieve their capacity by packing marks and lands more tightly together. These result in reduced recording and playing margins and sometimes lead to perceptible sound degradation, especially in older CD audio players which may not employ equalization (signal boosting). Consequently, many high speed recorder manufacturers recommend creating audio discs at reduced writing speeds while some recorders even limit their maximum speed to 24x when writing audio discs. In addition to slower recording speeds, some manufacturers also suggest using 74 minute instead of 80 minute discs. Several of the latest recorders even offer special writing modes which record audio discs with longer marks and lands than would normally be the case, albeit at the expense of some capacity. For example, an 80 minute disc written with longer marks and lands might only hold 74 minutes of audio and a 74 minute disc just 68 minutes of material.
DIGITAL PICTURES ON CD
What are the differences between Photo CD and Kodak Picture CD?
Eastman Kodak developed Photo CD and Picture CD to deliver and store high quality digital image files of pictures taken with conventional cameras and film. Photo CD was introduced in 1992 and is intended for professional and commercial applications while Picture CD came to market in 1999 aimed at the average consumer. Generally speaking, Photo CD discs store images using a proprietary file format (Image Pac) in, depending upon the version, five to six levels of resolution (128 x 192 to 2048 x 3072 or 4096 x 6144 pixels). Picture CD, on the other hand, employs the more common JPEG format in one resolution (1024 x 1536 pixels). In terms of capacity, Photo CD discs hold approximately 100 images and additional pictures can be added at later times. With Picture CD, however, images from a single roll of film are written at the time of original processing only. In addition, Photo CD compatible computer software is required to view and use Photo CD images but Picture CDs include on the discs a range of Windows and Macintosh applications to display, organize, enhance and email images.
What hardware is required to view images on Photo CD and Kodak Picture CD discs?
Both Photo CD and Kodak Picture CD discs are written in industry standard multisession (Mode 2, Form 1) format and are therefore playable on most computer CD-ROM drives and MultiRead-compliant (or other CD-R compatible) DVD-ROM drives and recorders. Historically, Photo CD images could be displayed on TV sets connected to dedicated Photo CD and multi-purpose Compact Disc Interactive (CD-i) players. These devices, however, are no longer available. Most recently, a few DVD-Video player models have come along incorporating Picture CD viewing capability.
Can DVD-Video players display digital still images written on CD-R and CD-RW discs?
In addition to select DVD-Video player models which are compatible with commercially produced Kodak Picture CDs some devices display JPEG images written to standard ISO 9660 formatted CD-R and CD-RW discs. It is anticipated that once OSTA’s MultiPhoto/Video specification is released more manufacturers will incorporate digital image viewing capabilities into their DVD-Video and even, perhaps, other consumer electronic devices. It is also possible to use a CD-R or CD-R/RW recorder and software to create Video CD 2.0 formatted discs containing slideshows of digital images which can be played back on many MultiPlay-compliant (or other CD-R or CD-RW compatible) DVD-Video players. Be aware, however, that not all DVD-Video players support the Video CD format and not all recording software creates Video CD slideshow discs.
What is MultiPhoto/Video?
The MultiPhoto/Video (MPV) specification is a collaborative effort between OSTA and the International Imaging Industry Association (I3A) and is currently under development. This specification will provide a standardized structure for still image digital photographs (JPEG, etc.) and video (eg. MPEG, AVI, etc.) stored on fixed and removable storage media, such as writable CD and DVD discs, flash memory cards and hard disk drives. This uniformity enables computer software and consumer electronics devices to more easily process collections of digital photographs and video and to play them back in the same way on any compatible device. To accomplish this goal MPV requires that, in addition to digital image files or video, an appropriately formatted storage medium must contain a defined table of contents and descriptive information (metadata) which the playing device will use for file navigation. In addition, MPV can also act as a protocol for exchanging information between software applications and services. It is expected that MultiPhoto/Video formatted CD-R and CD-RW discs will be created by a broad range of software including CD recording packages as well as digital camera, scanning, imaging and multimedia authoring software which support the MPV specification. Written discs could then be played back in MPV compliant devices and even in systems not supporting the specification, albeit in a more limited fashion. Since MultiPhoto/Video is simply an organizing system it is important to remember that the types of storage media and specific image and video file formats supported depend upon the individual capabilities of the particular devices or software employed.
DUPLICATION, REPLICATION AND PUBLISHING
What alternatives are available to copy CDs?
There are several different methods available to make one or multiple copies of existing CDs ranging from single CD-R and CD-R/RW recorders to specialized devices that automatically duplicate and label discs and, for large runs, commercial mass replication. Options are distinguished by cost, speed, convenience and capability. When dealing with commercial software and audio discs keep in mind copyright laws and that copy protection systems may be employed to hinder straightforward duplication.
Computer CD-R and CD-R/RW Recorders
By far the quickest and least expensive way to duplicate a disc is to simply copy it using a computer outfitted with a CD-R or CD-R/RW recorder combined with off the shelf writing software. In addition to creating discs from scratch many basic writing software packages duplicate most standard CD formats. Specialized copying software is also available with more sophisticated capabilities such as the ability to make backups of copy protected discs and even the power to simultaneous duplicate to multiple recorders. But remember that the ability of a system to copy specific disc formats depends upon the individual capabilities of the software, reader and recorder used. It is therefore advisable to check with the respective manufacturers for specific information.
Typically, discs are duplicated CD to CD by using the computer’s CD-ROM or DVD-ROM drive as the master source feeding the copying recorder. In cases where a separate reading drive is not available the master is first downloaded to the computer hard drive using the reading ability of the recorder and later written back to a blank disc using the same recorder. Employing the hard disk as an intermediate copying step is also a common tactic used when dealing with poor quality source discs or other situations where computer systems are not fast enough to keep up to the speed set on the recorder.
CD Duplication Systems
For copying larger numbers of discs various dedicated CD duplication solutions are available including machines that function by themselves or with the assistance of an operator. These configurations can either sit as standalone units or may be attached as computer peripherals. The most common devices are hand-fed tower systems which employ a number of CD-R or CD-R/RW recorders chained together for simultaneous duplication from either a master CD or from a hard drive. Also widely used are automated products incorporating robotic disc handling systems which mechanically load and unload one or more recorders. Sometimes disc label printers are included to produce a handful or even hundreds of finished discs per hour. Historically large and expensive, many CD duplication systems are now compact and affordable and within reach of many for personal and office use. A number of companies also offer commercial CD duplication services to perform short run work in quick turnaround times.
CD Mass Replication
In contrast to CD duplication which is usually performed on a small scale at the desktop level, CD mass replication is typically used to make huge quantities of discs such as commercial audio CDs and software CD-ROMs. These prerecorded (pressed) discs are manufactured from a mold in a factory setting and are created using a series of industrial processes including premastering, mastering, electroplating, injection molding, metallization, spin coating, printing and advanced quality control. In addition to manufacturing discs many replication companies offer companion services including packaging, printing, distribution and fulfillment.
What is CD publishing?
Somewhat like CD duplication equipment, CD publishing systems employ CD-R or CD-R/RW recorders but are used to create quantities of unique discs from different computer files rather than just to make multiple copies of a single master disc. Employing robotic disc handling systems and integrated label printers, many of these devices can be accessed over computer networks and shared much like office laser printers. Examples of CD publishing applications include retail audio CD vending kiosks, creating CD-Rs containing cheque images or monthly banking records, archiving computer-generated billing records to disc in place of microfilm and accepting conventional 35 mm film resulting in digital pictures on CD-R discs.
Can CD-R and CD-RW discs be protected against copying?
Historically, copy protection technologies were only available to protect prerecorded (pressed) discs but a variety of methods are now available to deter copying the contents of CD-Rs and CD-RWs, to authenticate media and even to forensically trace the origin of discs. Such capabilities are included in some CD-R and CD-R/RW recorders or may be offered as features in software tools as well as duplication and publishing systems.
DISC LABELING
What alternatives are available to label CD-R and CD-RW discs?
There are several different labeling methods available for CD-R and CD-RW discs ranging from hand writing, to adhesive labels, specialized devices that print directly onto the disc surface and ultimately the various commercial printing solutions. Each option is distinguished by cost, speed and convenience as well as by durability and the visual quality of the result. But keep in mind that applying any kind of label modifies the disc in a significant way. Thus, product warranties can be affected and unforeseen consequences may arise. It is, therefore, advisable to always follow manufacturer directions.
Hand Writing
By far the quickest and least expensive way to label a disc is to simply write on its top surface. Using a soft fiber or felt-tipped permanent marker is preferable but be aware that the solvents in some types of inks can migrate through the disc surface and potentially damage the reflective and dye layers beneath. The part of the disc least vulnerable to injury is the center clamping or hub area. Beware ballpoint pens or other sharp writing instruments as they may deform the disc substrate and delaminate the disc layers thereby causing information to become unreadable. Some discs are specially coated to accommodate handwritten labels and even some special markers are available and intended for such use.
Adhesive Labels
A more attractive way to label a disc is to apply an adhesive label. Several manufacturers offer inkjet and laser printer compatible products specifically designed for labeling discs as well as positioning devices to help with centering. Full surface or “donut-style” labels are preferable to partial stickers but be aware that any adhesive label can potentially upset the balance of a disc when playing back, especially at high speeds, causing excessive noise, vibration and data retrieval problems. Heat, humidity, handling and the passage of time can also compromise the stability of adhesive labels causing separation from the disc surface and even interfere with the drive. Sticky labels may not be the best choice when archiving important data as some types of label adhesives can react with and compromise the disc over time. Remember too that, once applied, labels should never be removed or repositioned. Even smoothing air bubbles can concentrate physical stresses in a small area and delaminate the disc.
Specialized Disc Printers
A range of specialized disc printing devices is also available to label discs in larger numbers and for imparting a more polished appearance. Currently, desktop products employing inkjet, thermal transfer and re-transfer technologies are available for directly labeling on the disc surface.
Inkjet
Inkjet printing technology has been available for many years and has proven extremely popular with consumers due to its high quality and cost effectiveness. Inkjet printers function by ejecting liquid ink from a print head onto the surface of a specially coated “inkjet-printable” disc. These special discs have an extra coating, called an Ink Absorption Layer (IAL), which receives the ink from the printer and allows it to stay in place long enough to dissipate its solvents and properly dry. Inkjet printers produce high-resolution full color images but there is a downside in that resulting labels can be smudged by high humidity or damp fingers. Inkjet printed discs should not be stored or shipped in form-fitting soft plastic envelopes as the chemicals used to keep the package materials supple can soften the inks causing the label to stick to the sleeve and potentially delaminate the disc when removed. Using jewelcases or other containers that do not come into direct contact with the printed surface is best.
Thermal Transfer
Unlike inkjet printers which spray liquid ink, thermal transfer printers convey solid pigment from a coated ribbon onto the surface of a disc through a combination of heat and pressure. Typically used to produce monochrome and spot color labels, thermal transfer printing does not require specially coated discs to accept the ink from the printing process. The results are, as well, reasonably durable. However, some disc surfaces give better results than others and offer more protection from potential damage during the printing process. Consequently, discs are available which feature special coatings optimized for thermal transfer printing. For labeling situations where discs share a largely common background appearance but vary slightly from disc to disc or among groups of discs some thermal transfer solutions can align and overprint their output onto partial images already screen printed onto the surface of the disc.
Re-transfer
More recently, re-transfer printers have come to market and function by applying heat and pressure to convey solid resins from an ink ribbon to a compliant intermediate film and then to the surface of the disc. Typically re-transfer systems produce photo-realistic color labels which are smooth and highly durable. Only certain types of disc surfaces are suitable for re-transfer printing including those optimized for thermal transfer use as well as some inkjet-printable surfaces and “crystal” protective coatings.
Commercial Printing
Various methods are used to commercially decorate discs including screen, offset, pad and flexographic printing. These are large-scale industrial processes typically used to label large numbers of discs with the same pattern or in situations when precise color matching is required for critical items such as company logos. In addition to desktop disc labeling, many duplication companies and replicators offer commercial printing services.
DISC HANDLING, STORAGE AND DISPOSAL
What is the best way to handle and store a CD-R or CD-RW disc?
A disc should always be handled by grasping its outer edges, center hole or center hub clamping area. Avoid flexing the disc, exposing it to direct sunlight, excessive heat and/or humidity, handle it only when being used and do not eat, drink and smoke near it. Discs should be stored in jewel cases rather than sleeves as cases do not contact the discs’ surfaces and generally provide better protection again scratches, dust, light and rapid humidity changes. Once placed in their cases discs can be further protected by keeping them in a closed box, drawer or cabinet. For long-term storage and archival situations it is advisable to follow manufacturer instructions. For further information consult the international standards for preserving optical media (ISO 18925:2002, Imaging materials — optical disc media — storage practices).
Should fingerprints and dust be cleaned off a CD-R or CD-RW disc?
CD technology is robust and employs several design elements to minimize the effects of fingerprints and minor scratches on data integrity. The first line of defense comes from the physical structure of the disc and the location of the data-bearing marks and lands. The reading laser beam shines through the disc’s substrate focusing beyond the contaminated surface and directly on the marks and lands beneath. In concert with advanced error detection and correction capabilities minor debris and abrasions are largely ignored. That said, handling care should be taken as above and a dusty disc should be blown off so that the dust does not enter the drive mechanism and accumulate on the lens or other optical components. It should also be noted that fingerprints, dust and scratches have a greater impact on recording than is the case with reading since the contaminants reduce the effectiveness of the writing laser by obscuring its beam from the disc’s recording layer.
What is the best way to clean a CD-R or CD-RW disc?
Dirty discs should be carefully cleaned using a soft dry lint-free cloth or camera lens tissue. Holding the disc by its outer edges or center hole gently wipe outward from the center hub toward the outside edge of the disc (just like the spokes of a bicycle wheel). Do not wipe the disc using circular motions as any scratches created will do the least damage if they cut across the track of marks and lands. More stubborn fingerprints or stains can be removed using a soft dry lint-free cloth lightly moistened with water or a commercially available CD cleaning fluid. Do not use vinyl record cleaners, lacquer thinner, gasoline, kerosene, benzene or other solvents, as they may damage the disc. Manufacturer directions should always be followed.
Can scratched and damaged CD-R and CD-RW discs be restored?
Often it is less expensive and makes more sense to transfer the data from a damaged disc onto a new one rather than to try to restore the problem disc. For dealing with more badly damaged situations consumer disc repair kits are available while several companies offer CD restoration and resurfacing equipment and services. See the resource listing in the appendix for contact information.
Is it possible to recover data from damaged CD-R and CD-RW discs?
Several software packages are currently available which diagnose disc problems and help recover deleted, unreadable or otherwise inaccessible information. A number of companies also offer commercial CD data recovery services. See the resource listing in the appendix for contact information.
What is the best way to destroy unwanted CD-R and CD-RW discs?
For office and high volume production situations various CD destruction options are available including mechanical shredders, desktop devices which employ heat and pressure to make disc unreadable and grinders which abrasively remove the disc’s reflective and data-bearing recording layers. A number of companies also offer commercial CD destruction services and deal with classified or other sensitive materials. See the resource listing in the appendix for contact information.
Can unwanted CD-R and CD-RW discs be recycled?
A number of companies offer CD recycling services and are able to reclaim some of the materials used in the disc’s construction. See the resource listing in the appendix for contact information.
DISC LONGEVITY
How many times can a CD-RW disc be rewritten?
As is the case with all optical storage media using phase change technology there is a limit to the number of times the recording layer in a CD-RW disc can be reliably switched between its crystalline and amorphous states. Currently, CD-RW discs can be rewritten approximately 1000 times.
What is the shelf life of unrecorded CD-R and CD-RW discs?
The unrecorded shelf life of a CD-R or CD-RW disc is conservatively estimated to be between 5 and 10 years.
How long will data recorded on CD-R and CD-RW discs remain readable?
The life span of a written disc depends upon a number of factors including such things as the intrinsic properties of the materials used in the disc’s construction, its manufactured quality, how well it is recorded and its physical handing and storage. As a result, the life span of a recorded disc is extremely difficult to estimate reliably. However, to calculate disc life spans within some practical timeframe blank media manufacturers do conduct accelerated age testing by subjecting samples of their discs to environments much beyond those experienced under normal storage conditions. Generally speaking, only the effects of varying temperature and humidity are considered. These test results are then used to predict how long a disc will remain readable under more normal storage conditions. Since questionable testing and measurement procedures can seriously impact upon and compromise these estimates several international standards have been developed which specify procedures to be used conducting accelerated testing and analyzing the resulting data from prerecorded (pressed) and recordable CDs:
ISO 18921:2002, Imaging materials — Compact discs (CD-ROM) — method for estimating the life expectancy based on the effects of temperature and relative humidity
ISO 18927:2002, Imaging materials — Recordable compact disc systems — method for estimating the life expectancy based on the effects of temperature and relative humidity
For years now many media manufacturers have performed their own lifetime evaluations using these or a variety of other homegrown tests and mathematical modeling techniques. Historically, manufacturers have claimed life-spans ranging from 50 to 200 years for CD-R discs and 20 to 100 years for CD-RW. Be aware, however, that disc producers, manufacturing methods and materials change over time as do applications and cost imperatives. Consequently, those concerned with disc longevity should consult the appropriate international standards and their media manufacturer for more particular information.
It is important to remember, however, that nothing lasts forever and that technologies inevitably change. Well-designed products, such as CD-R and CD-RW, allow for seamless transition to the next generation and ultimately, since they embody digital information, contents can be transferred to future storage systems as becomes necessary to preserve whatever has been stored on the discs.
DISC TESTING AND VERIFICATION
Is it necessary to verify a CD-R or CD-RW disc after recording?
Verifying discs after writing helps maintain an appropriate quality level. The amount of ongoing integrity checking and data verification that may be necessary is really a question of acceptable risks for any particular application. For example, letting recording software conduct data comparisons immediately after writing is usually sufficient in casual settings but critical data archiving and large-scale duplication may call for more comprehensive testing. This is due to the differences that often exist among recorders, drives and players. For example, recorders typically incorporate higher quality optical systems and lenses with slightly larger numerical apertures than do reading devices. Consequently, successfully verifying a written disc on a recorder does not guarantee broad playing compatibility, especially in cases where disc jitter is marginal.
How can the quality of a written CD-R or CD-RW disc be assessed?
Several methods can be used to assess the quality of a written disc. These include measuring its optical signals, examining the integrity of its physical and logical formats, performing interchange testing and conducting data verification. Each method is a piece of the quality testing puzzle. The extent to which a disc needs to be tested depends, of course, upon the imperatives of the application.
At a basic level it is possible to confirm that information has been correctly written to a disc by comparing it against the source material using the verification features found in many off the shelf writing software packages. When somewhat more detailed analysis is warranted, interchange testing can be performed to provide some practical indication of real-world compatibility. To accomplish this, audio CDs are played back in a number of consumer audio players to check for quality issues while data discs are checked in a variety of CD-ROM and DVD-ROM drives to make sure that recorded information is completely recoverable and at speeds established by the manufacturers. Specialized computer software controlling everyday CD-ROM drives can also be used to read a disc at a lower level of organization to verify that its physical and logical formats conform to industry specifications.
For situations which require appraising the more fundamental physical characteristics, a number of commercial analysis tools are available to examine the optical signal characteristics of a recorded disc and thus identify low-level errors. Typically, these devices are standalone or computer-attached and employ CD audio or CD-ROM drives specially modified to measure various disc parameters and provide descriptive reports. As is the case in testing generally, results can vary significantly among inspection systems so, to maintain continuity, discs should always be evaluated on the same pieces of equipment. Commercial CD testing companies offering quality verification services using such devices are also widely available.
An important question which has always existed for compact disc testing is the uncertainty of the relationship between the results derived from evaluating discs on low-level analyzers and real world disc performance in the installed population of reading and playing devices. Over the years a succession of groups and companies have labored to reconcile these two product classes through the use of various multi-point calibration discs and other vehicles. However, given the extremely rapid technological evolution of reading and playing devices it is impossible to conclusively establish any definitive link between measured and actual performance, especially for marginal discs.
When assessing disc quality keep in mind the huge number of variables involved. These include such things as the discs with their different types, batches and manufacturers, recording software and hardware in their many varieties and versions, diverse recording conditions encountered, different test equipment employed, operators of differing experience and even the handling of the discs themselves. Consequently, judgements should be made on a relative rather than absolute basis.
What is the construction of a CD-R disc?
Just like all kinds of CDs a CD-R disc is a sandwich of a number of layers. First comes a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside diameter of the disc. On top of this substrate is an organic dye recording layer (cyanine, phthalocyanine or azo) followed by a thin metal reflective layer (gold, silver alloy or silver) and finally an outer protective lacquer coating. Some discs are also topped with additional layers that improve scratch resistance, increase handling durability or provide surfaces suitable for labeling by inkjet or thermal transfer printers.
How are CD-R discs made?
Current CD-R disc manufacturing lines are extremely efficient, incorporating all major production elements to produce a staggering number of discs. The first step in producing a CD-R disc is to create the polycarbonate plastic substrate using an injection molding process. The dye layer is applied using spin coating and the reflective layer by means of cold planar magnetron sputtering. The lacquer overcoat is then applied by another spin coating procedure followed by ultraviolet curing. Additional durability or printable layers are typically applied using screen printing methods.
Why are the recording surfaces of various kinds of CD-R discs different colors?
Due to the intrinsic absorption spectrums of the various dyes, the thickness of the layers and the type of reflector materials used the recording side of a CD-R disc can appear many different colors including shades of green, yellow and blue. For many years the color of a disc was incidental in its design but some manufacturers now intentionally aim for specific visual effects. For example, CD-R discs are now available which mimic the look of prerecorded (pressed) CDs and tinted substrates are sometimes even used to make discs appear black or exotic colors. Keep in mind, however, that disc operation is not affected by its visual appearance. While the human eye perceives a rainbow of colors, all of the discs function the same way when illuminated by the 780 nm laser of a CD-ROM drive or recorder.
What are the differences between the dyes - cyanine, phthalocyanine and azo?
The recording layer of a CD-R disc is composed of one of cyanine, phthalocyanine or azo dye and, although each has its own recording and longevity characteristics, they all serve the same purpose. Over time, there has even been a steady convergence in their properties.
Information is written to a CD-R disc by means of a laser to heat and alter the dye sufficient to create a pattern of marks and thereby mimic the pits of a molded CD. Although each dye is tuned to absorb light in the range of 780 nm, they all respond differently to the writing laser. Some dyes become bleached from exposure to the beam while the others create permanent features and deform the underlying substrate. In addition, each dye requires a different laser intensity and duration to properly form marks.
Early CD-R discs employed cyanine-based dye exclusively and recording conditions defined in Orange Book Part II standards were tuned around cyanine characteristics. As the market evolved discs using phthalocyanine and azo dyes emerged and specifications changed to reflect the new reality. Since then, recorders select write strategies appropriate for the type of dye and carefully control the laser beam as required to achieve the best results with all types of media.
In terms of their composition, quenchers (metal dithiochelates, benzenaminium salts, etc.) are normally added to cyanine dyes to increase light stability while phthalocyanine and azo dyes are intrinsically less sensitive to light exposure after recording.
Remember that CD-R discs are complex engineering marvels so when it comes to choosing among them keep in mind the importance of selecting products based on your particular requirements rather than focusing on any one characteristic.
What is the construction of a CD-RW disc?
To allow information to not only be written but also re-written many times over, CD-RW disc construction is more complex than that of CD-R. A CD-RW disc uses a six-layer design beginning with a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside edge of the disc. Next comes a dielectric layer (zinc sulfide and silicon dioxide), followed by a phase change alloy recording layer (indium, silver, tellurium, and antimony), another dielectric layer, a thin metal reflective layer (aluminum) and finally a protective lacquer overcoat.
How are CD-RW discs made?
As with CD-R, producing CD-RW discs involves using multiple manufacturing stages including injection molding, sputtering, spin coating, ultraviolet curing and quality inspection. The first step is to create the substrate by injection molding. The dielectric layers, phase change recording and reflective layers are applied to the substrate using cold planar magnetron sputtering. Spin coating and ultraviolet curing are then used to apply the protective lacquer coating. Since the sputtering process lays down the phase change alloy in its amorphous condition powerful lasers are used to initialize the disc and return the recording layer back to its crystalline state.
Are there any meaningful differences among blank discs produced by different manufacturers?
As with all products, discs produced by competing companies are distinct from one another because they may employ different designs, use materials from various suppliers and are manufactured by different factories, equipment and workers. However, all blank discs conform to Orange Book Part II (CD-R) or Part III (CD-RW) specifications and should work in all recorders. Discs are differentiated based on brand names, quality and consistency, features, price and packaging. Some recorder companies may test particular brands of discs more extensively than others so it may be advisable to inquire of the recorder manufacturer for specific recommendations depending on particular applications.
SUGGESTED FURTHER READING AND
RESOURCES
BOOKS
Apple Computer, Inc. The Apple CD-ROM Handbook: A Guide to Planning, Creating, and Producing a CD-ROM. Reading: Addison-Wesley, 1992.
Bouwhuis, Gijs, et. al. Principles of Optical Disc Systems. Bristol: Adam Hilger, 1985.
Brown, Martin C. CD Recordable Solutions. Cincinnati: Muska and Lipman, 2001.
Caffarelli, Fabrizio, and Deirdre Straughan. Publish Yourself on CD-ROM: Mastering CDs for Multimedia. New York: Random House, 1992.
Chambers, Mark L. Hewlett-Packard Official Recordable CD Handbook. Foster City: IDG Books, 2000.
Chambers, Mark L. Recordable CD Bible. Foster City: IDG Books, 1997.
Chambers, Mark L. CD and DVD Recording for Dummies. New York: Hungry Minds, 2001.
Marchant, Alan B. Optical Recording: A Technical Overview. Reading: Addison-Wesley, 1990.
Ogletree, Terry William, and Todd Brakke. The Complete Idiot's Guide to Creating Your Own CDs. 2nd ed. Indianapolis: Macmillian, 2002.
Pahwa, Ash. The CD-Recordable Bible: An Essential Guide for Any Business. Wilton: Eight Bit Books, 1994.
Purcell, Lee. CD-R/DVD: Disc Recording Demystified. New York: McGraw-Hill, 2000.
Purcell, Lee, and David Martin. The Complete Recordable-CD Guide. Alameda: Sybex, 1997.
Pohlmann, Ken C. The Compact Disc Handbook. 2nd ed. Madison: A-R Editions, 1992.
Pohlmann, Ken C. Principles of Digital Audio. 4th ed. New York: McGraw-Hill, 2000.
WHITE PAPERS
Bennett, Hugh. Running Optimum Power Control: Data Integrity in CD-Recording. Santa Barbara: Optical Storage Technology Association, 1998.
Busk, Philip J. et. al. Compact Disc Terminology. 2nd ed. Wilmington: Disc Manufacturing, Inc., 1993.
Busk, Philip J. Integrating Mixed-Mode CD-ROM. Wilmington: Disc Manufacturing, Inc., 1992.
DeMoulin, Robert, Toshi Iizuka, and Rod Volturno. CD Recordable Handbook: A Guide to Choosing the Right CD Recorder for You. 2nd ed. San Jose: Ricoh Corporation, 1995.
Disc Manufacturing, Inc. A Glossary of CD and CD-ROM Terms. Wilmington: DMI, 1993.
Disc Manufacturing, Inc. An Overview to Multimedia CD-ROM Production. Wilmington: DMI, 1992.
Eastman Kodak Company. Data Integrity on CDs. Rochester: Eastman Kodak Company, 1995.
Eastman Kodak Company. Permanence, Care, and Handling of CDs: Including CD-ROM, Writable CD, and Kodak Photo CD. Rochester: Eastman Kodak Company, 1995.
Eastman Kodak Company. Why Kodak Writable CD Media with Infoguard Protection System? Rochester: Eastman Kodak Company, 1995.
Hamelinck, Dirk, Bob Ijtsma, and Eggert Gudmundsson. Mount Rainier: Drag and Drop Data on CD-RW. Eindhoven: Royal Philips Electronics, 2000.
Multi Media Masters and Machinery. A ‘Revolution’ in CD-R and DVD-R Spin Coating. Yverdon-les-Bains: Multi Media Masters and Machinery, 1999.
Multi Media Masters and Machinery. CD-R and DVD-R: Ready for the Present, Prepared for the Future. Yverdon-les-Bains: Multi Media Masters and Machinery, 2000.
Multi Media Masters and Machinery. The Next Wave in Optical Storage: CD-RW and Rewritable DVD. Yverdon-les-Bains: Multi Media Masters and Machinery, 2000.
Philips Electronics. Basic Principles of CD-Recordable/Rewritable Digital Audio. Eindhoven: Philips Electronics, 1998.
Philips Electronics. CD-ReWritable: How it Works. Eindhoven: Philips Electronics, 1997.
Plextor Europe. The Process of Writing. version 1.0. Zaventem: Plextor S.A./N.V., 2002.
Royal Philips Electronics. Thermo-Balanced Writing. Eindhoven: Philips Electronics, 2001.
Roohi, Misty. More than CD: Enhanced CD Formats. Wilmington: Disc Manufacturing, Inc., 1996.
Summers, Clayton. Introduction to ISO 9660. Wilmington: Disc Manufacturing, Inc., 1995.
Warner, Josh. The Enhanced CD Fact Book Version 1.01. Cupertino: Apple Computer, 1995.
STUDIES
Doculabs, Inc. Compatibility of CD-R Media, Readers, and Writers. Chicago: Doculabs, 1997.
Hartke, Jerome L. CD-R Media Survey. Marlborough: Media Sciences, 2000.
Optical Disc Manufacturing Association. Variation of Measurement. Milford: ODMA, 1995.
Optical Storage Technology Association. CD-R/DVD-ROM Compatibility Study. Santa Barbara: OSTA, 1998.
Optical Storage Technology Association. CD-R Compatibility Study Phase 1. Santa Barbara: OSTA, 1997.
Optical Storage Technology Association. CD-R Compatibility Study Phase 2. Santa Barbara: OSTA, 1998.
Stinson, Douglas, Fred Amell, and Nick Zaino. “Lifetime of Kodak Writable CD and Photo CD Media.” SIGCAT DISCourse 9.1 (1995): 1+.
| PERIODICALS |
|
| Computer Technology Review |
www.wwpi.com |
| EMedia, the Digital Studio Magazine |
www.emedialive.com |
| Medialine |
www.medialinenews.com |
| One to One |
www.oto-online.com |
| Optical Disc Systems |
www.opticaldisc-systems.com |
| Software Business Magazine |
www.softwarebusinessonline.com |
| Tape Disc Business |
www.tapedisc.com |
| |
|
| PRINT DIRECTORIES |
|
| Billboard International Disc/Tape Directory |
www.billboard.com |
| EMedia, the Digital Studio Magazine Buyer's Guide |
www.emedialive.com |
| The Gold Book |
www.oto-online.com |
| The International DVD and CD Plant Directory |
www.oto-online.com |
| |
|
| EXHIBITIONS AND TRADE SHOWS |
|
| AES |
www.aes.org |
| CeBIT |
www.cebit.de |
| COMDEX |
www.comdex.com |
| Digital Content Delivery Expo |
www.dcdexpo.com |
| International Consumer Electronics Show |
www.cesweb.org |
| Media-Tech Expo |
www.media-tech.net |
| NAB |
www.nab.org |
| PC Expo |
www.techxny.com |
| Replication Asia |
www.replicationasia.com |
| |
|
| GENERAL INFORMATION WEB SITES |
|
| Andy McFaddenÆs CD-Recordable FAQ |
www.cdrfaq.org |
| BurnWorld |
www.burnworld.com |
| CD Freaks |
www.cdfreaks.com |
| CD Media World |
www.cdmediaworld.com |
| CDR Zone |
www.cdr-zone.com |
| CDR-Info |
www.cdrinfo.com |
| CDRLabs |
www.cdrlabs.com |
| CDROM-Guide |
www.cdrom-guide.com |
| CD-RW Central |
www.cdrwcentral.com |
| cd-rw.org |
www.cd-rw.org |
| Digital Drives |
www.digitaldrives.com |
|
|
| GENERAL INFORMATION INTERNET NEWSGROUPS |
|
| comp.publish.cdrom.hardware |
|
| comp.publish.cdrom.software |
|
| comp.publish.cdrom.multimedia |
|
| alt.comp.periphs.cdr |
|
|
|
| INDUSTRY ASSOCIATIONS AND ORGANIZATIONS |
|
| 1394 Trade Association |
www.1394ta.org |
| CDs21 Solutions |
www.cds21solutions.org |
| Consumer Electronics Association (CEA) |
www.ce.org |
| Industrial Technology Research Institute (ITRI) |
www.itri.org.tw |
| International Disc Duplicating Association (IDDA) |
www.discdupe.org |
| International Federation of the Phonographic Industry (IFPI) |
www.ifpi.org |
| International Optical Disc Replicators Association (iODRA) |
www.iodra.com |
| International Recording Media Association (IRMA) |
www.recordingmedia.org |
| Optical Disc Manufacturing Association (ODMA) |
www.odma.com |
| Optical Storage Technology Association (OSTA) |
www.osta.org |
| Orange Forum |
www.orangeforum.or.jp |
| SCSI Trade Association |
www.scsita.org |
| USB Implementers Forum |
www.usb.org |
|
|
| LICENSING AND STANDARDS ORGANIZATIONS |
|
| American National Standards Institute (ANSI) |
www.ansi.org |
| ECMA International |
www.ecma.ch |
| International Committee for Information Technology Standards |
www.ncits.org |
| International Electrotechnical Commission (IEC) |
www.iec.ch |
| International Organization for Standardization (ISO) |
www.iso.org |
| Optical Storage Technology Association (OSTA) |
www.osta.org |
| Philips Intellectual Property and Standards |
www.licensing.philips.com |
INDUSTRY AND PRODUCT CONTACTS
| MARKET RESEARCH AND CONSULTING FIRMS |
| Cahners In-Stat Group |
www.instat.com |
| Forget Me Not Information Systems Inc. |
73144.1631@compuserve.com |
| Gartner, Inc. |
www.gartner.com |
| IDC |
www.idcresearch.com |
| InfoTech, Incorporation |
www.infotechresearch.com |
| Magnetic Media Information Services (MMIS) |
www.mmislueck.com |
| Santa Clara Consulting Group |
sccg@pacbell.net |
| Strategic Marketing Decisions (SMD) |
www.smdcorp.com |
| Techno Systems Research Co., Ltd. (TSR) |
phone: 03-3866-4505 |
| Understanding and Solutions |
www.uands.com |
|
|
| DUPLICATION AND PUBLISHING SYSTEMS |
| Alea Systems, Inc. |
www.alea.com |
| Alera Technologies, LLC. |
www.aleratec.com |
| An Chen Computer Co. Ltd. |
www.copystar.com.tw |
| Ashby Industries, Inc. |
www.ashbyindustries.com |
| Bernardini SRL |
www.bernardini-srl.com |
| CopyPro, Inc. |
www.copypro.com |
| Copytrax Technologies |
www.copytrax.com |
| Cyclone USA |
www.cdcyclone.com |
| Discmatic |
www.discmatic.com |
| DixxPli USA |
www.dixxpli.com |
| Hoei Sangyo Co., Ltd. |
www.hoei.co.jp |
| ILY Enterprise Inc. |
www.ily.com |
| Imedia Technologies (IMT) |
www.imt-sa.com |
| Interactive Media Corporation |
www.interactivemediacorp.com |
| JukeBox Information Systems |
www.jbis.com |
| LSK Data Systems GmbH |
www.lskdata.de |
| Luminex Software, Inc. |
www.luminex.com |
| MediaFORM, Inc. |
www.mediaform.com |
| Mediatechnics Systems |
www.mediatechnics.com |
| Microboards Technology |
www.microboards.com |
| Microsynergy |
www.idt-microsynergy.com |
| Microtech Systems |
www.microtech.com |
| Niscoa, Inc. |
www.niscoa.com |
| Nistec Corporation |
www.nistec.co.jp |
| Odixion USA |
www.odixionusa.com |
| OptoMedia Storage Solutions Limited |
www.optomedia.co.uk |
| Orient Instrument Computer Co., Ltd. |
www.orient-computer.co.jp |
| Otari, Inc. |
www.otari.com |
| Primera Technology |
www.primeratechnology.com |
| Rimage Corporation |
www.rimage.com |
| Rimax International |
www.rimax.net |
| R-Quest Technologics, LLC |
www.r-quest.com |
| Terra Computer Systems |
www.terra.cz |
| The Logical Company |
www.u-master.com |
| T.S. Solutions |
www.ts-solutions.com |
| Telex Communications, Inc. |
www.telex.com |
| Verity Systems |
www.veritysystems.com |
| Young Minds, Inc. |
www.ymi.com |
| Wytron Technology Co. Ltd. |
www.wytron.com.tw |
|
|
| DISC LABELS AND PRINTERS |
|
| Alera Technologies, LLC. |
www.aleratec.com |
| Avery Dennison Corporation |
www.avery.com |
| Burlington Paper |
www.burlingtonpaper.com |
| CopyPro, Inc. |
www.copypro.com |
| Fellowes |
www.fellowes.com |
| Kyso Inc. |
www.kyso.com |
| MediaFORM, Inc. |
www.mediaform.com |
| Memorex Products |
www.memorex.com |
| Neato |
www.neato.com |
| Odixion USA |
www.odixionusa.com |
| Primera Technology |
www.primeratechnology.com |
| Rimage Corporation |
www.rimage.com |
| Verity Systems |
www.veritysystems.com |
|
|
| DISC MANUFACTURERS/BRANDS |
|
| Alera Technologies, LLC. |
www.aleratec.com |
| CDA Datentrêger Albrechts GmbH |
www.cda.de |
| CMC Magnetics Corp. |
www.cmcdisc.com |
| Daxon Technology Inc. |
www.daxontech.com |
| Doremi Media Co., Ltd. |
www.doremi4u.co.kr |
| Emtec-Multimedia Inc. |
www.datastoremedia.com |
| Fujifilm Computer Products |
www.fujifilmmediasource.com |
| Gigastorage Corporation |
www.gigastorage.com |
| Imation Corp. |
www.imation.com |
| KDG Mediatech AG |
www.kdg-mt.com |
| Lead Data Inc. |
www.leaddata.com.tw |
| Maxell Corporation |
www.maxell.com |
| Memorex Products |
www.memorex.com |
| Mitsui Advanced Media, Inc. |
www.mitsuicdr.com |
| Moser Baer India Ltd. (MBI) |
www.glyphicsmedia.com |
| Moulage Plastique de LÆOuest (MPO) |
www.hi-space.com |
| PNY Technologies |
www.pny.com |
| Prodisc Technology Inc. |
www.prodisc.com.tw |
| Quantegy, Inc. |
www.quantegy.com |
| Ritek Corporation |
www.ritek.com.tw |
| Sony Electronics Inc. |
www.mediabysony.com |
| Summit Hi-Tech Pte Ltd. |
www.smsummit.com.sg |
| Taiyo Yuden Co. Ltd. |
www.yuden.co.jp |
| TDK Electronics Corp. |
www.tdk.com |
| Techo Plus Digital Disc |
www.technoplus.it |
| Verbatim Corporation |
www.verbatim.com |
| Viva Magnetics Limited |
www.viva.com.hk |
|
|
| RECORDER MANUFACTURERS/BRANDS |
| Actima Technology Corporation |
www.actima.com.tw |
| Alera Technologies, LLC. |
www.aleratec.com |
| AOpen Inc. |
www.aopen.com |
| Behavior Tech Computer Corp. |
www.btc.com.tw |
| BenQ Corporation |
www.benq.com |
| CenDyne Inc. |
www.cendyne.com |
| CyberDrive |
www.cyberdrive |
| Digital Research Technologies |
www.dr-tech.com |
| Hewlett-Packard Company |
www.hp.com |
| Hi-Val |
www.hival.com |
| I/O Magic Corporation |
www.iomagic.com |
| Imation Corp. |
www.imation.com |
| Infinite Data Storage (IDS) |
www.infinitedtastorage.com |
| Iomega Corporation |
www.iomega.com |
| LG Electronics Inc. |
www.lge.com |
| Lite-On IT |
www.liteonit.com |
| Matsushita Kotobuki Electronics Industries, Ltd. |
www.mke.panasonic.co.jp |
| Micro Solutions Inc. |
www.microsolutions.com |
| Mitsumi Electric Co., Ltd. |
www.mitsumi.com |
| Philips Electronics |
www.philips.com |
| Pioneer Electronics |
www.pioneerelectronics.com |
| Plextor Corp. |
www.plextor.com |
| Ricoh Company |
www.ricoh.com |
| Samsung Electronics Co., Ltd. |
www.samsung.com |
| Sanyo Electric Co., Ltd. |
www.burn-proof.com |
| Sony Corporation |
www.sony.com |
| TDK Electronics Corp. |
www.tdk.com |
| Teac Corporation |
www.teac.com |
| Toshiba |
www.toshiba.com |
| Ultima Electronics Corp. |
www.ultima.com.tw |
| Yamaha Corp. |
www.yamaha.com |
|
|
| RECORDING SOFTWARE PUBLISHERS |
| Ahead Software |
www.nero.com |
| Aplix Corporation |
www.aplix.com |
| B.H.A. Software Corporation |
www.bhacorp.com |
| Charismac Engineering |
www.charismac.com |
| Elaborate Bytes |
www.elby.ch |
| Fangmeier Sytemprogrammierung |
www.feurio.com |
| Gear Software |
www.gear.com |
| Golden Hawk Technology |
www.goldenhawk.com |
| HyCD, Inc. |
www.hycd.com |
| NewTech Infosystems |
www.ntius.com |
| Oak Technology |
www.oaktech.com |
| Padus, Inc. |
www.padus.com |
| PoINT Software and Systems |
www.pointsoft.de |
| Roxio, Inc. |
www.roxio.com |
| Software Architects, Inc. |
www.softarch.com |
| Veritas Software |
www.veritas.com |
| VOB Computersysteme GmbH |
www.vob.de |
|
|
| JUKEBOXES AND NETWORK STORAGE |
| ASACA Corporation |
www.asaca.com |
| ASM GmbH & Co. KG |
www.asm-jukebox.de |
| DAX Archiving Solutions |
www.smartdax.com |
| DISC Gmbh |
www.disc-gmbh.com |
| JVC Professional Products Company pro.jvc.com |
pro.jvc.com |
| Kubik Enterprises Inc. |
www.kubikjukebox.com |
| Luminex Software, Inc. |
www.luminex.com |
| Pioneer Electronics |
www.pioneerelectronics.com |
| Plasmon |
www.plasmon.com |
| PowerFile, Inc. |
www.powerfile.com |
| Procom Technology, Inc. |
www.procom.com |
|
|
| DISC QUALITY ANALYSIS AND TESTING |
| Adivan High Tech AG |
www.adivan.com |
| aeco NV |
www.aecogroup.com |
| AudioDev |
www.audiodev.com |
| CD Associates, Inc. |
www.cdassociates.com |
| Cube Technologies GmbH |
www.cube-tec.com |
| Clover Systems |
www.cloversystems.com |
| DaTARIUS Technologies GmbH |
www.datarius.com |
| Eclipse Data Technologies |
www.eclipsedata.com |
| Efocus International Ltd. |
www.efocus.co.uk |
| Quantized Systems |
www.quantized.com |
| Sony Precision Technology, Inc |
www.sonypt.com |
| StageTech Developments AB |
www.stagetech.se |
|
|
| DISC REPAIR, RESTORATION AND DATA RECOVERY |
| Action Front Data Recovery Labs, Inc. |
www.actionfront.com |
| Acodisc |
www.acodisc.com |
| ArrowKey, Inc. |
www.cdrom-prod.com |
| AuralTech |
www.auratech.com |
| CD Data Guys |
www.cddataguys.com |
| CD Recovery Services |
www.cdrecovery.com |
| Compact Disc Repairman, Inc. |
www.cdrepairman.com |
| Digital Innovations |
www.digitalinnovations.com |
| ESS Data Recovery |
www.savemyfiles.com |
| Naltech |
www.naltech.com |
| Ontrack Data International |
www.ontrack.com |
| Skippy Disc |
www.skippydisc.com |
|
|
| DISC DESTRUCTION AND RECLYCLING |
| Alera Technologies, LLC. |
www.aleratec.com |
| CD ROM Incorporated |
www.cdrominc.com |
| Ecodisk |
www.ecodisk.com |
| EcoMedia |
www.ecomedia.com |
| GBC ModiCorp Limited |
www.gbcmodi.com |
| Greendisk |
www.greendisk.com |
| Hammacher Schlemmer and Company |
www.hammacher.com |
| Hetzel Elektronik-Recycling GmbH |
www.her-online.de |
| Intimus Business Systems |
www.intimus.com |
| Lacerta Group, Inc. |
www.lacerta.com |
| MBA Polymers, Inc. |
www.mbapolymers.com |
| MRC Polymers |
www.mrcpolmers.com |
| Niscoa, Inc. |
www.niscoa.com |
| Sony Disc Manufacturing |
www.sdm.sony.com |
Courtesy of Adaptec, makers of Easy CD Creator. All contents copyright Adaptec, 1999.
A | B | C | D | E | F | G | H | I | J | L | M | O | P | R | S | T | U | V | Y
A
a-characters
The character set used in the ISO 9660 Volume Descriptors. It consists of capital A to Z, digits 0 to 9, and the following symbols: (space) ! " % & ' ( ) = * + , - . / : ; < ? > _
A-Time
(or absolute time) In an audio CD, the time elapsed since the beginning of the disc. It can be used in determining the start and stop times of sound segments for programming an application on a mixed-mode disc, measuring from the very beginning of the data area (including the computer data in Track 1).
Aspect Ratio
An image's width to height ratio.
ASPI
Advanced SCSI Programmer's Interface. A layer of code which manages communication between software and SCSI cards.
Authoring
What you do to create an application which may eventually be stored on CD. For example, if you wish to create a multimedia game or presentation, you will need authoring software that allows you to combine sound, graphics, and text with user interactivity. When you have finished creating your application with authoring software, you can use CD recording software such as Easy CD Creator or Toast to write it to CD.
Auto-Insert Notification
A feature of Windows operating systems which causes an audio CD to be played or an application disc to launch an application (for some discs) as soon as the disc is mounted in a CD drive. With earlier CD-R software it was recommended that this feature be turned off, but with Easy CD Creator and DirectCD it is preferable to leave it on. This setting must be made for each CD unit separately; in Windows 95 it can be made in Control Panel | System | Device Manager | CD-ROM | [your CD-ROM drive] | Settings
B
Barcode
A unique code for a compact disc. With recordable CDs, this number is often printed in the clear inner ring of the disc. Some CD recorders can also read this information digitally.
Block
See sector.
Bootable
A CD (or floppy, hard disk, or other storage media) from which a computer can be started up, because it contains all the operating system software the computer needs to run. A bootable CD contains a bootable image - a file which is an exact representation of a boot floppy or hard drive. Bootable CDs are usually made according to the El Torito standard.
Buffer
An amount of memory which temporarily stores data to help compensate for differences in the transfer rate of data from one device to another. In CD recorders, the buffer helps to prevent buffer underruns.
Buffer Underrun
A buffer underrun occurs when your computer system cannot keep up the steady stream of data required for CD recording. The CD recorder has an internal memory buffer to protect against interruptions and slowdowns, but if the interruption is so long that the recorder's buffer is completely emptied, a buffer underrun occurs, writing stops, and most often the recordable CD is ruined. See also About Buffer Underruns.
C
Caddy
The plastic and metal carrier into which a CD must be inserted before it is loaded into some CD-ROM drives or CD recorders (others have a tray which slides out to receive the disc, and do not need caddies).
CD Bridge
A set of specifications defining a way of recording CD-I information on a CD-ROM XA disc. Used for Photo CD and Video CD.
CD Extra or CD Plus
A multisession disc containing a number of audio tracks in the first session, and one CD-ROM XA data track in the second session. Additional characteristics are defined in the Blue Book standard. An alternative to mixed-mode for combining standard CD-DA audio (which can be played in a normal audio player), and a computer application, on a single disc.
CD+G
(aka karaoke) A special disc disc format in which simple graphics and text are stored in the subchannels of an audio disc, but you need a special player to read and display this information. The data in the subchannels cannot be copied with most current systems or software.
CD-DA
Compact Disc-Digital Audio. Jointly developed by Philips and Sony and launched in October, 1982, CD-DA was the first incarnation of the compact disc, used to digitally record and play back music. The standard under which CD-DA discs are recorded is known as the Red Book.
CD-I
A compact disc format developed by Philips, designed to allow interactive multimedia applications to be run on a player attached to a television. The standard document defining CD-I is called the Green Book.
CD-R
Compact disc-recordable. When referring to recordable discs (media), "CD-R" is often used to refer to write-once discs, in contrast to CD-RW. See also Recordable Disc.
CD-ROM
Compact Disc-Read Only Memory. A standard for compact disc to be used as digital memory media for personal computers. The specifications for CD-ROM were first defined in the Yellow Book.
CD-ROM Drive
A peripheral device attached to a computer which allows it to read/play a CD-ROM disc. All CD-ROM players can also play back audio CDs, but you need external headphones or speakers to hear them.
CD-ROM XA
"XA" stands for Extended Architecture. CD-ROM XA is an extension of the Yellow Book standard, generally consistent with the ISO 9660 logical format but designed to add better audio and video capabilities (taken from the CD-I standard) so that CD-ROM could more easily be used for multimedia applications. CD-ROM XAwas abandoned as an independent multimedia format, but Photo CD discs are written in the CD-ROM XA physical format.
CD-RW
CD-ReWritable. CD recordable media which can be erased and re-recorded. CD-RW media can only be written in a CD-RW recorder, not in a normal CD recorder, though a CD-RW recorder can also record standard CD-R discs. More information on the read-back compatibility of CD-RW discs.
CD Text
An audio CD format in which up to 5000 characters of disc information (title, artist, song titles, etc.) is written into the disc Table of Contents. This information is displayed when the disc is played back on CD Text-enabled players.
CD-WO
Compact Disc-Write Once. A rarely-used term for recordable compact disc.
Close Disc
To "close" a recordable disc so that no further data can be written to it. This is done when the last session's lead-in is written. The next writeable address on the disc is not recorded in that lead-in, so the CD recorder in subsequent attempts to write has no way of knowing where to begin writing. Note: It is NOT necessary to close a disc in order to read it in a normal CD-ROM drive.
Close Session
When a session is closed, information about its contents is written into the disc's Table of Contents, and a lead-in and lead-out are written to prepare the disc for a subsequent session.
Coaster
Popular term for a ruined recordable CD, named after the round object you rest your drinking glass on so that it doesn't mark the table.
Cue Sheet
In Easy-CD Pro for Windows 3.1, a list of tracks which will be written one after the other in the same session without user intervention. Generally used to create multi-track audio or mixed-mode discs.
D
d-characters
The character set used in ISO 9660 Level 1 filenames, if the standard is strictly adhered to (which is not always necessary). Consists of capital A to Z, digits 0 to 9, and the underscore symbol ( _ ).
DAT
Digital Audio Tape.
Data Area
In ISO 9660, the space on a CD-ROM where the user data is written. It begins at the physical sector address 00:02:16.
Digital Audio Extraction
The process of copying CD-DA audio tracks digitally, from your CD recorder or CD-ROM drive, to hard disk or to recordable CD. Not all CD-ROM drives support this (but most CD recorders do)! For more information.
Disc-at-Once
A method of writing CDs in which one or more tracks are written in a single operation, and the disc is closed, without ever turning off the writing laser. Contrast with Track-at-Once. Not all CDrecorders support Disc-at-Once. For more information.
Disc Image
A single large file which is an exact representation of the whole set of data and programs as it will appear on a CD, in terms of both content and logical format. This may be an ISO 9660 image (adhering strictly to the ISO 9660 standard), or some proprietary format such as the .cif format used by Easy CD Creator.
E
EAN
See UPC.
ECC
Error Correction Code. A system of scrambling data and recording redundant data onto disc as it is recorded. During playback, this redundant information helps to detect and correct errors that may arise during data transmission.
EDC
Error Detection Code. 32 bits in each sector which are used to detect errors in the sector data.
EnhancedCD
See CD Extra.
Extent
A sequential set of sectors in which a file or portion of a file is recorded.
F
File System
A data structure that translates the physical (sector) view of a disc into a logical (files, directories) structure, which helps both computers and users locate files. In other words, it records where files and directories are located on the disc. See also Logical Format.
Firmware
In a CD recorder, firmware is the programming instructions contained on a ROM chip within the CD recorder which tell the recorder how to respond to commands issued by software. Some firmware is flash-upgradeable, meaning that you can upgrade the firmware by running a piece of software on the computer attached to the recorder. Other firmware is coded into non-rewriteable chip, so the entire chip must be changed in order to upgrade the firmware.
FPS
Frames per second.
Frame
A single, complete picture in a video or film. A video frame is made up of two interlaced fields of either 525 lines (NTSC) or 625 lines (PAL). Full-motion video for NTSC runs at 30 frames per second (fps); for PAL, 25 fps. Film runs at 24 fps.
G
Gap
The gap (more correctly called a pause) is a space dividing tracks on a CD. In some situations a gap is required by the standards (Red Book and other "color" books). For example, if you have data and audio tracks within the same session, they must be separated by a gap. Also, there must be a gap of 2 to 3 seconds preceding the first track on a disc.
The gap which "belongs" to a track is actually the gap before it, not the one after it. This is why on some audio CD players you will see a countdown (-02, -01, etc.) before a track begins - itÐs counting down to the next track, not counting up from the end of the last one.
H
Header Field
Four bytes recorded at the beginning of each sector which tell the address of the sector (expressed as a Logical Block Number) and the mode in which the sector is recorded.
HFS
The file system used by the Macintosh operating system to organize data on hard and floppy disks. Can also be used for CD-ROMs.
High Sierra Format
The standard logical format for CD-ROM originally proposed by the High Sierra Group, on which the ISO 9660 standard is based; essentially identical to ISO 9660. The original High Sierra format is no longer used.
Hybrid
Under the Orange Book standard for recordable CD, hybrid means a recordable disc on which one or more sessions are already recorded, but the disc is not closed, leaving space open for future recording.
However, in popular use the term "hybrid" often refers to a disc containing both DOS/Windows and Macintosh software, which on a DOS/Windows platform is seen as a normal ISO 9660 disc, while on a Mac it appears as an HFS disc.
I
Indexes
Indexes provide additional starting points within a single audio track. Not all audio CD players support indexes. Index markers are written into the Q subchannel and are incremented by 1 sequentially during the track.
ISO 9660 Format
The most common international standard for the logical format for files and directories on a CD-ROM. Some other common logical formats such as Joliet and Rock Ridge are extensions of ISO 9660.
ISO 9660 Image
See disc image.
ISO 9660 Interchange Levels
Methods of recording and naming files on disc under the ISO 9660 standard. There are three nested, downward-compatible Levels.
In Level 1 (the lowest common denominator, developed with DOS file naming limitations in mind):
- Each file must be written on disc as a single, continuous stream of bytes -- files may not be fragmented or interleaved.
- A filename may not contain more than eight d-characters.
- A Filename Extension may not contain more than three d-characters.
- A directory name may not contain more than eight d-characters.
In Level 2, again, each file must be written on disc as a single, continuous stream of bytes, but there are no restrictions on filenames.
In Level 3 there are no restrictions at all.This allows for writing files in multiple extents, so it is used for packet writing.
ISRC
International Standard Recording Code. Some recorders allow the ISRC to be recorded for each audio track on a disc. The code is made up of: Country Code (2 ASCII characters), Owner Code (3 ASCII characters), Year of Recording (2 digits), Serial Number (5 digits).
J
Jewel Case
The hinged plastic case in which CDs are often stored.
Jewel Case Sleeve
The pieces of paper which can be inserted into the jewel case to help identify the contents of the CD stored in the case.
Joliet
Joliet is an extension of the ISO 9660 standard, developed by Microsoft to allow CDs to be recorded using long filenames, and using the Unicode international character set. Joliet allows you to use filenames up to 64 characters in length, including spaces. For more information.
L
Lead-In
An area at the beginning of each session on a recordable compact disc which is left blank for the session's Table of Contents. The lead-in is written when a session is closed, and takes up 4500 sectors on disc (1 minute, or roughly 9 megabytes). The lead-in also contains next writeable address on the disc, so that future sessions can be added (unless the disc is closed).
Lead-Out
An area at the end of a session which indicates that the end of the data has been reached. The first lead-out on a disc is 6750 sectors (1.5 minutes, about 13 megabytes) long; any subsequent lead-outs are 2250 sectors (.5 minute, about 4 megabytes).
Link Block
A block (aka sector)of digital rubbish which is written each time the recording laser is turned on (before) or off (after) writing a track or a packet. See also Run-in/Run-out Blocks.
Linked Multisession
A disc containing more than one session, in which all (or selected) data from the various sessions can be seen as if it had all been recorded in a single session. For more information.
Logical Block
The smallest addressable space on a disc. Each logical block is identified by a unique Logical Block Number (LBN), assigned in order starting from 0 at the beginning of the disc. Under the ISO 9660 standard, all data on a CD is addressed in terms of Logical Block Numbers.
Logical Format / Logical Structure / File System
A file system such as ISO 9660 translates the sector-by-sector view of a compact disc into a virtual "tree" of directories and files, which makes it easier for both humans and computers to use the information on the disc. UDF is another example of a file system which can be used to write CDs.
M
Mastering
Technically, refers to the process of creating a glass master from which compact discs will be reproduced in quantity. In desktop recordable CD systems, mastering is done together with premastering by the desktop CD recorder, and the term is generally used to mean "recording."
Mixed-Mode Disc
A compact disc including both computer data and CD-DA tracks. The data is all contained in Track 1, and the audio in one or more following tracks. Contrast with CD Extra.
MMC
A standard command set used by some CD recorders. Many newer recorders follow this standard, though many of them also interpret it differently (so there are still differences in how software must address these recorders, in spite of the standard).
Mode 1
A somewhat inaccurate way of referring to the CD-ROM physical format. More information.
Mode 2
A not-quite-accurate but common way of referring to the CD-ROM XA physical format. More information.
Mount
To install a compact disc so that the computer recognizes its presence and can read data from it.
MP3
MP3 is a scheme for compressing audio. MP3 files do not maintain the quality of audio CD tracks, and cannot be recorded directly to CD as standard audio tracks. They can be recorded as data tracks and played back via your computer using an appropriate player software, or converted to Wave files and then recorded to CD.
MPEG
Motion Picture Experts Group, a standards organization responsible for the MPEG 1 and MPEG 2 standards for the compression of full-motion video.
MSCDEX
Microsoft DOS extensions for CD-ROM. Allows the DOS and Windows 3.x operating systems to recognize a CD-ROM disc.
MultiRead
An OSTA standard for CD-ROM and DVD-ROM drives. Drives which follow the MultiRead standard can read commercial CDs (audio and data), CD-R discs, and CD-RW discs. They can also read discs written in fixed- or variable-length packets. For more information, see the MultiRead Specification.
Note! Drives which have the MultiRead logo issued by Hewlett-Packard have been tested for compliance with the MultiRead specification. Drives labeled as "multi-read" (without the logo) probably have not been tested for compliance with the specification, and may not be able to read CD-RW or packet-written discs.
Multisession
A method of adding data incrementally to a CD in more than one recording session. If data is linked between session, all data on a multisession disc, when read on a multisession CD-ROM drive, may be seen as part of a single logical structure. Multisession is very different from packet writing. For more information.
Multivolume
A disc containing multiple sessions which are not linked together, so that each "volume" on the disc must be read as if it were a separate disc. You can read different sessions on a disc using the Session Selector in Easy CD Creator Deluxe.
N
NTSC
The standard used for broadcast television in the U.S., whose resolution is 525 horizontal lines at 30 frames per second.
O
On the Fly
To write on the fly means to write directly from source data to CD data without first writing a disc image.
Optimum Power Calibration Area
(OPC Area) A special area near the center of the recordable disc. Before writing a track on a disc, the CD recorder must adjust the amount of power applied to the writing laser to an optimum level for each individual disc. The optimum calibration area is reserved for this purpose.
Orange Book
The Philips/Sony specification for Compact Disc Magneto-Optical (CD-MO) and Write-Once (CD-WO) systems - in other words, the standard by which recordable CDs are recorded.
P
Packet Writing
A method of writing data on a CD in small increments (contrast with Track-at-Once and Disc-at-Once). Packets can be of fixed or variable length. Adaptec's DirectCD software requires packet writing. For more information.
PAL
Phase Alteration by Line. The standard used for broadcast television in much of Europe and Asia, with a resolution of 768 pixels x 576 horizontal lines at 25 frames per second.
PCA
Power Calibration Area. See OPC.
Photo CD
A compact disc format based on the CD-ROM XA and Orange Book Hybrid Disc specifications, used to store photographic images for display and printing.
Physical Format
The physical format of a compact disc determines how data is recorded in each sector. The various physical formats are defined by the color book standards (e.g., Red Book, Yellow Book, etc.) For more information.
PMA
(Program Memory Area) On a recordable disc, an area which "temporarily" contains the Table of Contents information when tracks are written in a session which is not yet closed. When the session is closed, this same information is written in the session lead-in.
Premastering
The process of preparing data to be recorded onto a compact disc. This includes dividing the data into sectors and recording those sectors with the appropriate header (address) and error correction information. In the case of recordable CD systems, premastering and mastering are done in one operation, resulting in a ready-to-read compact disc.
Q
QSIF
Quarter-SIF. A format for compressed video with a resolution of 176 (horizontal) x 112 (vertical) x 29.97(fps) for NTSC and 176(h) x 144(v) x 25.00(fps) for PAL. QSIF allows for low data rates suitable for Internet applications.
R
Random Erase
(Available with CD-RW discs and DirectCD for Windows 2.x). The ability to erase a single file at a time from a CD-ReWritable disc, freeing up disc space for immediate re-use, just as you would do on a hard or floppy disk.
Recordable Disc
The media used in recordable CD systems. The blank disc is made of a bottom layer of polycarbonate, with a preformed track spiral which the recording laser follows when inscribing information onto the disc. A translucent layer of recordable material is laid on top of the polycarbonate, then a reflective layer (gold or silver colored). On top there is a thin layer of lacquer and sometimes a printed label. The standard recordable disc is "write-once" -- data written to it cannot be erased, although it is possible to add data in a later session (see Multisession). For erasable/rewritable discs, see CD-RW.
Red Book
The Philips/Sony specification for audio (CD-DA) compact discs.
Rock Ridge
An extension of the ISO 9660 file system designed to support UNIX file system information (such as longer filenames and deeper directory structures).
Romeo
A file naming option in Easy-CD 95 and Easy-CD Pro 95 (both obsolete and replaced by Easy CD Creator) which allows you to write files to disc with names up to 128 characters long, including spaces. This was a stopgap solution to the problem that Windows NT 3.5a did not support Joliet. Romeo did not support the Unicode character set nor associated DOS (short) filenames. Romeo filenames can be read on Windows 95 and NT 3.51 systems. Romeo discs can be read on Macintosh systems if the filenames are shorter than 31 characters. For more information.
Run-In/Run-Out Blocks
Blocks of data written before and after a packet or a track, to allow the recorder to synchronize with the data on disc, and to finish up interleaved data. Four run-in blocks and two run-out blocks are written for each packet.
S
SCSI
Small Computer System Interface (pronounced "scuzzy"). An interface which allows up to seven peripheral devices to be linked to a single controller.
Sector
The smallest recordable unit on a CD. A disc can contain [(75 sectors per second) x (60 seconds per minute) x (number of minutes on disc)] sectors. The amount of data contained in the sector depends on what physical format it is recorded in; for "regular" CD-ROM data, you can fit 2048 bytes (2 kilobytes) of data into a sector.For more information.
Sequential Erase
(Available with CD-RW discs.) Erasing the entire disc so that it can be re-used.
Session
As defined in the Orange Book, a recorded segment of a compact disc which may contain one or more tracks of any type (data or audio). In data recording, there is usually only one track per session. In audio recording, all audio tracks are contained in a single session. A lead-in and lead-out are recorded for every session on a disc.
Session-at-Once
Session-at-Once is a subset of Disc-at-Once, used for CD Extra. In Session-at-Once recording, a first session containing multiple audio tracks is recorded in a single pass, then the laser is turned off, but the disc is not closed. Then a second (data) session is written and closed.
SIF (Standard Input Format)
A format for compressed video specified by the MPEG committee, with resolutions of 352 (horizontal) x 240 (vertical) x 29.97 (fps) for NTSC and 352 (horizontal) x 288 (vertical) x 25.00 (fps) for PAL. SIF-resolution video provides an image quality similar to VHS tape.
Spindown
Many new CD-ROM drives save power by spinning down (stopping the drive's spin) when the drive is not in use. This may cause buffer underruns when recording a CD by copying tracks or files from another CD-ROM drive, if the drive "goes to sleep" and cannot be woken up quickly enough to keep up with the CD recorder's demand for a constant stream of data.
Subchannels (or subcodes)
Audio CDs have 8 subchannels of non-audio data interleaved with the audio data, called the P, Q, R, S, T, U, V, and W channels. You can think of them as small, separate streams of data running alongside the audio, which can be read by a player at the same time as the audio, if the player is "smart" enough to interpret them. For example, CD+Graphics discs (karaoke) store rudimentary graphics and text in the subchannels, but you need a special player to read and display this information.
The P and Q channels are used to tell an audio player how to play back an audio disc. The Q channel contains the index markers. In the pause (gap) before a track begins, the index marker is set to 0 (zero). When a track begins, the index marker changes to 1. (If a track contains subindexes, these are incremented by 1 sequentially during the track. In this case the Q channel might contain 1, 2, 3, 4, etc.) When the track ends, the Q channel index marker goes back to 0, then re-starts at 1 when the next track begins.
T
Table of Contents
For a whole disc or any session within a disc, shows the number of tracks, their starting locations, and the total length of the data area. The TOC does NOT show the length of each track, only its starting point.
Track
Every time you write to CD, you will create at least one track, which is preceded by a gap. Any session may contain one or more tracks, and the tracks within a session may be of the same or of different types (for example, a mixed-mode disc contains data and audio tracks).
Track-at-Once
A method of writing data to disc. Each time a track (data or audio) is completed, the recording laser is stopped, even if another track will be written immediately afterwards. Link and run blocks are written when the laser is turned on and off.
U
UDF
Universal Disc Format. A file system endorsed by OSTA (the Optical Storage Technology Association) for use with packet writing and other recordable optical disc technologies, such as DVD. For more information.
UPC
Universal Product Code. With some CD recorders, you may define a thirteen-digit UPC catalog number for the entire disc, which will be written in the disc's Table of Contents. Also known as EAN.
V
Video CD
A standard for displaying full motion pictures with associated audio on CD. The video and sound are compressed together using the MPEG 1 standard, and recorded onto a CD Bridge disc. Video CD disc contains one data track recorded in CD-ROM XA Mode 2 Form 2. It is always the first track on the disc (Track 1). The ISO 9660 file structure and a CD-I application program are recorded in this track, as well as the Video CD Information Area which gives general information about the Video CD disc. After the data track, video is written in one or more subsequent tracks within the same session. These tracks are also recorded in Mode 2 Form 2. The session is closed after all tracks have been written.
Volume
Under the ISO 9660 standard, "volume" refers to a single CD-ROM disc. However, "volume" is often used to mean a session on a multisession disc which is not linked to other sessions.
Volume Descriptors
For an ISO 9660 disc, the Volume Descriptors are a set of optional information fields recorded at the beginning of the data area on the disc. They were originally designed for the needs of CD-ROM publishers. The full set of Volume Descriptors is as follows:
System Name: The operating system under which the application will run. This Volume Descriptor may contain a maximum of 32 a-characters, and its use is optional.
Volume Name: This is the disc name which is displayed by your operating system when the disc is mounted. It may contain a maximum of 32 a-characters, and its use is recommended.
Volume Set Name: If the CD you are preparing is part of a set of discs, every disc in the set may have an identical Volume Set Name, recorded in this field. The Volume Set Name may contain a maximum of 32 d-characters, and its use is optional.
PublisherÐs Name: Identifies the publisher of the disc. Maximum 128 a-characters allowed, use is optional.
Data PreparerÐs Name: Records the name of author of the content of the disc. Maximum 128 a-characters allowed, use optional.
Application Name: Records the name of a particular application needed to access the data on the disc, if any. Maximum 128 a-characters allowed, use optional.
Copyright File Name: Authors can protect their work with a copyright notice stored in a file which must be placed in the root directory. The name of this file may be recorded in the Copyright File Name Volume Descriptor. Maximum: 8+3 d-characters, use optional.
Abstract File Name: This field records the name of an file stored in the root directory which describes the contents of the disc. Maximum: 8+3 d-characters, use optional.
Bibliographic File Name: This field stores the name of a file (which may be recorded in any directory) containing bibliographic information such as an ISBN number. Maximum: 8+3 d-characters, use optional.
Date Fields: There is a Volume Descriptor field for each of four dates (Creation, Modification, Expiration, Effective), in the format: year, month, day; hour, minute, second. All these fields are optional.
Y
Yellow Book
The book which sets out the standard developed by Philips and Sony for the physical format of compact discs to be used for information storage (CD-ROM).
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