With today's young generation, the same impact can be obtained with the question, "Daddy, were CDs around when you were born?" You could be in your second year of college and would have to answer 'no' to the second question. With the disappearance of vinyl records and with VHS sales steadily losing market share to DVD sales, we can clearly see that CDs and DVDs have made a significant impact on our society. The depth of this industry is far greater than many can imagine. There are many questions and there is some degree of confusion about the many CD and DVD formats. This 3 part series will provide some interesting historical facts and provide a large volume of information about CDs and DVDs in an effort to answer those questions.

The architectural roots of CD/DVDs date back to the cylindrical record player. The music data, or wave form, was scribed onto the surface of the cylinder as it rotated. As the cylinder rotated the scribe would move along the axis of the cylinder. So when the cylinder made 1 full revolution the scribe would be offset by one track width and thereby forming a helix which is somewhat similar to the Slinky coiled wire toy. Later improvements to the record player changed the record format from a cylinder to a flat disk. Here the helix was flattened to a spiral somewhat similar to a wristwatch mainspring.

The music data was laid down starting from the outside rim and progressed to the center. It was around 90 years later before the audio CD was introduced to the market. The music data was laid down on the CD in a spiral fashion, except it starts near the center and progresses out to the rim and instead of scribing the wave form, the music is recorded digitally with pits and lands on the reflective surface of the CD.

History

The following are some interesting benchmark dates that were extracted from the following references [1] [2] [3] that marked the progression of technology to the present day CD. A more comprehensive listing can be found in those references.

1855 Leon Scott de Martinville developed the 'Phonoautograph'. This machine recorded vibrations on a carbonized paper cylinder but was unable to playback the sounds.

1877 Thomas Edison invented the tinfoil 'Phonograph'. This machine recorded vibrations on a tinfoil cylinder and was able to playback the sounds.

1885 Chichester Bell and Charles Tainter made a minor improvement by using a stylus that cut a groove into wax cylinder and applied for a patent for their version of the phonograph known as the 'Graphaphone'

Note: In the three machines listed above, sound waves moved the stylus up and down to scribe indentations on the recording cylinder.

1887 Emily Berliner departed from the wax cylinder in preference to a flat rubber disc. A scribe recorded the music in a spiral track going from the outside rim to center of the disc. The sound waves move the scribe from left to right in lieu of up and down as recorded in earlier machines. Berliner's phonograph became know as the 'Gramophone'.

1904 The Odean company in Britain introduces discs recorded on both sides.

1915 78 rpm records were introduced.

1928 33 1/3 rpm records were introduced.

1937 A. Reeves invents pulse code modulation (PCM), a technology used in computers and CDs.

1947 Magnetic tape recorders hit the US markets.

1948 The transistor was invented at Bell Laboratories.

1949 45 rpm records were introduced.

1958 The Laser was invented.

1958 The integrated circuit was introduced.

1967 NHK Technical Research Institute demonstrates a 12-bit PCM digital audio recorder with a 30 kHz (30,000 times per second) sampling rate. Recordings go onto a high-grade videotape.

1971 Microprocessor produced by Intel

1972 Compaan and Kramer produced a color prototype of the new CD technology.

1977 Mitsubishi, Hitachi & Sony show digital audio disc prototypes at the Tokyo Audio fair.

1978 Philips releases the Video Disc player. Philips also proposes a standard CD diameter of 11.5 cm and indicates that polycarbonate would be the best material for a CD.

Note: This same year a decision was made for the data track on a CD to start on the inside and spiral towards the outer edge, yet the reasoning was not given.

1978 Sony sells the PCM-1600 and PCM-1 digital audio processors.

1979 Prototype CD system demonstrated in Europe and Japan.

Note: Why are CDs 74 minutes instead of something convenient like 60 minutes? References have it that Sony and Philips and a few others were the market leaders in this new technology both of which having slightly different standards. Initially, Philips had proposed an 11.5 centimeter diameter CD which had a run time of 60 minutes. Representatives from the Sony Corporation found the 60 minute runtime unacceptable because Beethoven's Ninth Symphony would not fit on the CD. Subsequently, both companies joined into collaboration to devise an acceptable standard and as a result we have the 74 minute CD and Beethoven's 9th Symphony fits comfortably. The diameter had to be increased to 12.0 centimeters to accommodate the increased time. Also, they agreed that the sampling rate should be 44.1 KHz with 16 bit granularity; both values affect the quality of sound.

1980 Philips and Sony propose a standard for the Compact Disc (CD).

1982 Compact Disc Technology is introduced to Europe and Japan.

1983 Compact Disc Technology is introduced to the United States.

1983 Second Generation and Car CD players are introduced.

1985 Third Generation CD players released.

1988 CD-Recordable disc and recorder technology introduced.

1996 CD-ReWritable disc and recorder technology introduced.

Color Books

There are times when shopping for CD equipment, CD burning software or even CD blanks that you may read the product's specifications and they may indicate compliance with the Red Book, or there may be a reference to a Yellow Book or somewhere else one may read about an Orange book reference. One may wonder what all of these books are about and just how many colors are there and will this product be compatible with my system? These books, designated with different colors, define various standards for the CD industry and tell you what your hardware, software or CD media can or cannot do. The first book of CD specifications was written in 1982 by Philips and Sony and the original specifications were bound in a red cover and became know as the Red Book, thus the start of the color book designations. Listed below are the 8 color books and a brief of their application. [4]

Red Book, CD-A This book was the original standard for the Compact Disc - Audio including the physical characteristics of any CD, like track width and pit dimensions. This book is the basis for all later CD standards and specifications. The book also defines the format for a CD-DA (Compact Disc - Digital Audio) in order to correctly play on a CD player. The standard provides for 99 tracks (songs), 44.1 kHz sampling rate, 16-bit quality, yielding a 74 min playtime.

Yellow Book, CD-ROM This book, written in 1988, laid out the specifications for the CD-Read Only Memory format. This was an extension of the Red Book whereby it specified how a CD could contain data other than audio. This book only defines the physical arrangement of the data on the disc and is used in conjunction with other standards that defines directory and file structures. This book also addressed more technical areas like optical stylus parameters, control/display system and sector structure. The record structure was defined in two data modes, i.e. Mode 1 and Mode 2.

Mode 1 defined a data block to be 2,352 bytes where 2,048 bytes were used for data and 304 bytes were used for added error detection and correction. Mode 2 defined 2,336 byte data blocks where the entire block could be used for data. This mode facilitated storing graphics and video and allowed different kinds of data to be mixed together and this mode became the basis for CD-ROM XA (eXtended Architecture).

Orange Book, CD-MO, CD-R, CD-RW This book provides specifications for the recordable CD standards. This book is divided into three sections. Part 1 deals with CD -Magneto-Optical disc. Part 2 deals with the specification for the CD - Recordable disc. Part 3 deals with CD - ReWritable). In addition to the 3 formats, this book also addressed more technical things like data organization, multi-session, hybrid disks, pre-groove modulation and recommendations for reflectivity, environment and light speed.

Part 1, CD-MO technology allowed tracks to be written and erased on 12 cm CDs that allowed millions of rewrites. These drives used 2 heads, one laser head to write and the other magnetic head to erase, in a double pass process. This CD can be rewritten indefinably; however strong magnetic fields could disrupt the data patterns. Part 2, CD-R technology is a write-once process similar to the older WORM (write once, read many) products. The first tracks are the calibration area followed by the lead-in area where the table of contents is written. Next came the program area where the user data was recorded followed by the lead-out area. Media for these CDs are pre-grooved to facilitate head tracking of the recorder. Part 3, CD-RW was added later in 1996 as an extension to the Orange Book. This book details phase change technology and the UDF (Universal Disc Format) to produce a CD that can be rewritten on one pass.

White Book, VCD This book provides specifications for the Video CD. VCD is a special adaptation of CD-ROM XA that is designed to hold MPEG1 video data. This book also addresses more technical things like track usage, MPEG audio/video track encoding, play sequence descriptors, data retrieval structures, data fields for fast forward and reverse and close captioning.

Green Book, CD-I This book provides specifications for the CD-Interactive. This book address more technical specifications like adaptive differential pulse-code modulation, track layout sector structure, and conversion of sound to binary stored along with other types of media. It specifies synchronization of various kinds of data and file compression for multimedia applications.

Blue Book, E-CD This book provides specifications for stamped Enhanced-CD. This defines format for inclusions of multimedia data like video clips, text and images on a standard CD-A. There are a number of CD formats in this Enhanced-CD family and they will be described later.

Scarlet Book, SACD This book provides specifications for Super Audio Compact Disc. This defines format for high-resolution audio formats that features complex six-channel sound. This format departs from the pulse code modulation and uses direct stream digital where none of the sound data is lost. The sampling rate of 2.8 MHz improves the complexity and realism of sound. DSD enables a frequency response of 100kHz and a dynamic range of 120 dB. This specification provides for three types of disc format, single layer, dual layer and dual layer hybrid.

Purple Book, DDCD This book provides specifications for the Double Density Compact Disc. A DDCD had about twice the capacity of a standard CD and this book provides the specification to change the physical dimensions of the data tracks and pits that are burned or pressed into a CD to accomplish increased capacity. First, the spiral track width is changed to 1.1 micron instead of the 1.6 micron and the pit length is changed to .623 micron instead of the .833 micron. These physical changes will yield a CD with a capacity of 1.2 gigabytes.

ISO 9660 This book defines the naming convention for a CD. Each file name must consist of three components: name, extension and version number. There are three nested, downward compatible levels used to record the names on the CD.

Level 1 developed with DOS limitations in mind, restricts filenames to 8 characters and extensions to 3 characters and directory names are limited to 8 characters. The file must be written as a continuous stream of bytes. Level 2 indicates the file must be written as a single continuous stream of bytes but there is no restriction on the name except the name and extension has to be less than 30 characters. Level 3 has no restrictions except that the name and extension has to be less than 30 characters.

Joliet This book was developed with the Windows 95 in mind. It allows CD to utilize long filenames up to 64 characters and it also incorporated the use of Unicode.

Rock Ridge This book was developed with the Unix system in mind. It specifies longer file names with more complex character sets and symbolic links for files.

CD Formats

There are variations, extensions, bridging or crossovers and hybrids to the color book standards whereby an individual may not grasp all of the CD formats that have been produced. The following will list most of the known formats and give a brief description of their application as extracted from references [4][5].

CD - A, (CD - Audio) Red Book. This is the same as CD-DA. This format is defined to hold digital audio used primary as music CDs although they could also hold sound bits or music loops for music editing software, etc.

CD - BD, (CD - Bridge Disc) White Book. This format is defined as a CD-ROM XA disc that included Yellow Book Mode 2 user data that can also be played on CD-I players. Additional codes in the CD-ROM XA tracks allow the output to be shown on a TV screen.

CD - DA, (CD - Digital Audio) Red Book. This format is defined to hold digital audio used primary as music CDs, although they could also hold sound bits of music loops for music editing, etc.

CD - E, (CD - Extra) Blue Book. This is one of several names in the E-CD family. See E-CD for details.

CD + G, (CD + Graphic) Red Book. The CD-DA format provided several sub-channels that made provisions for low-resolution graphics on an audio CD. Systems that can interpret sub-channels R through W will be able to display these graphics.

CD - I, (CD - Interactive) Green Book. This format is used in business and education multimedia interactive applications. Generally it uses proprietary hardware, operating system (OS9) and data compression solutions (MPEG-1). The players range in cost and sophistication and can display on NTSC televisions in the United States and PAL televisions overseas.

CD - IR, (CD - Interactive Ready) modified Red Book. This format is a CD-Audio disc that includes a CD-I application and can be played with a modified CD-I player. The usages are unclear but are suspected to be similar to the CD-I disc.

CD - MO, (CD - Magneto/Optical) Orange Book. This format is similar to the CD-R recordable CD where all forms of data can be recorded. Furthermore, this CD can be erased and re-recorded indefinitely. This format does require a special drive.

CD - P, (CD - Plus) Blue Book. This is one of several names in the E-CD family. See E-CD for details.

CD - R, (CD - Recordable) Orange Book. This very popular format provides desktop recordable CDs similar to stamped CD-DA and CD-ROMs where various types of audio, video, graphics and text data can be recorded.

CD - RDx, (CD - Read-only Data eXchange) Probably modified Yellow Book. The CIA developed this format for system and software interoperability in order to publish one integrated collection of data and indexes to be accessible on any ISO 9660 compatible computer.

CD - ROM, (CD - Read Only Memory) Yellow Book. This format is the standard the industry uses to produce commercially stamped CD-ROMs for software distribution. Standard CD-ROMs adhere to the ISO 9660 file naming convention.

CD - ROM XA, (CD - Read Only Memory Extended Architecture) extended Yellow Book. Yellow Book defines Mode 1 and Mode 2. This extended architecture defines two new types of sectors, Form 1 and Form 2, within the Mode 2 category. These sectors are used for data, graphics, video and ADPCM compressed audio in an interleaved scheme (CD-I structure), making it possible to read and display jointly text, graphics and audio files of various sample sizes and up to 20 hours of 4 bit monaural sound. As an example, Kodak's Photo CD uses this extended architecture.

CD - R/W, (CD - ReWritable) Orange Book. This popular format provides desktop recordable CDs similar to stamped CD-ROMs where various types of audio, video, graphics and text data can be recorded, erased and re-recorded.

CD - S, (CD - Singles) modified Red Book. These are 8cm music singles that were popular in Japan in the '90s and could be played in the Sony Data Discman.

There were some CD-ROM XA applications that were ported to the 8cm format. Note that these 8 cm CD-S should not be confused with the Sony 8cm MiniDisc, which is MO, magneto-optical, rewritable technology.

CDTV, (Commodore Dynamic Total Vision) Yellow Book. This format followed the CD-ROM format but used the CDFS file system that met the ISO 9660 standard. This CD was used in Commodore PCs and may still exist in foreign markets.

CD - WO, (CD - Write Once) Orange Book. The distinction between this format and the CD - R format has diminished with the enhancements of CD-R specifications.

The CD-WO was the WORM (Write Once, Read Many) application to the 12cm CD industry where data may be written in several sessions, but once written it could not be changed.

There does seem to be a distinction in the media used for CD-WO where ablative, phase transition, bubble formation, alloy formation or texture change technology is used in the recording surface. Apparently, this format was used in the business environment for document archival, audit trails, scientific record archival, imaging and imaging archival.

DDCD, (Double Density CD) Nimbus Technology and Engineering proposed this format in 1994 claming to encode more than 2 hours on a CD. Optical Disc Corp also proposed a similar format in late 1993. Both corporations proposed to increase the number of track by reducing the track width.

These efforts did not attract the attention of Philips, Sony, or others major players whose proposals led to the DVD specifications.

E - CD, (Enhanced CD) Blue Book specification. This format is technically known as stamped multi-session and is used to refer to any audio CD that has CD-ROM data added. These CDs have around 60 minutes of music of the 74 minutes that are available. Recording artists have used the remaining space for video clips, artist profiles, lyrics, interviews, animations, promotional material and even games.

Karaoke - CD, Red Book. The CD-DA format provided several sub-channels that made provisions for low-resolution graphics on an audio CD. Systems that can interpret sub-channels R through W will be able to display these graphics.

Photo - CD, extended Yellow Book. The Photo - CD is a hybrid disc that uses the CD-ROM XA Form 1 sector structure to store up to 100 35mm photographs.

SVCD, (Super Video CD), White Book. This format is an enhancement of the VCD where it provides menu command picks and several other options not available in the VCD format. Newer DVD players can handle this format when indicated in the product specifications.

SACD, (Super Audio CD), Scarlet Book. This format provides for high fidelity audio sound and includes 5.01 channel surround sound in addition to 2 channel stereo. New SACD drives are required to benefit from the enhanced sound quality; however, the SACD will play on standard CD players but without the enhanced sound.

VCD, (Video CD), White Book. This format provides the specifications for video image recording onto CD. References indicate this format may have been derived from the Karaoke - CD concepts. This CD can store 72-74 minutes of full motion video and 2 channel digital audio using MPEG-1 compression in a CD-ROM XA bridge disc structure. The video data transfer rate is 1.44 Mbits/sec, which makes the image quality somewhat comparable to a VHS tape.

What is Next?

A lot of research has produced a large volume of data that has been presented here on the CD development. Next month, in part 2 of this series, foundation data will be provided on DVDs. In the last series, the CD and DVD data will be pulled together in a comparison and information will be presented on future CD and DVD products.