The CD sampling rate is 44.1kHz and there are 32 bits per sample, so the data rate of the encoded analog data is 1.41Mbps, but the inclusion of parity, synch, and subcode bits raises the real data rate to 4.3Mbps. A CD will hold about 650 Mb, or about 74 minutes of stereo, 16-bit audio. The digital portion of the CD audio system is not stereophonic, but sequential monaural. See also Control and Display signals. Compare with Direct Stream Digital. The CD file format is defined by ISO 9660. For more information on CD standards, please see Sound on Sound, “Compact Disc Formats” by Mike Collins, January 1998. See also SACD. (Super Audio Compact Disc.) The CD specification is specified in “books,” each defining the standard for a particular type of CD:

Blue Book: CD Data (CD Extra)

The latest of the books to appear, this specifies the CD Extra format, designed to include CD-ROM data on a standard (audio, Red Book) CD. A CD Extra is actually a multisession CD, containing the audio tracks in its first session, followed by a data track in the second session, etc.

Red Book: System Description Compact Disc Digital Audio (CD-DA)

CD-DA (Digital Audio) Established in 1980 as the first of the books which defined consumer audio on CD. A Red Book CD may have up to 99 tracks; each track is divided into blocks of data called sectors; each sector contains, in addition to audio data, EDC/ECC, and 98 control bytes of PQ subcodes.

Yellow Book: System Description Compact Disc Read-Only Memory (CD-ROM)

CD-ROM (Read Only Memory). Yellow Book extends the Red Book specification by adding two new track types:

CD-ROM Mode 1: Storage of computer data

Mode 1 sectors include an improved ECC for Data.

CD-ROM Mode 2: Compressed audio, video, picture data

Mode 2 (Forms 1 & 2) CD-ROM/XA (Extended Architecture) is used to integrate computer data with compressed audio and/or video, including Photo CD and Karaoke CD.

White Book: System Description Compact Disc Bridge (CD-V)

Developed to cover the CD-V (Video) format, and supported by JVC, Matsushita, Philips, and Sony. These are a special kind of CD-ROM/XA bridge disc that allows the play of films and music videos on a dedicated CD-V player, or on a CD-i player equipped with a CD-V cartridge, or a computer with a CD-ROM/XA drive, an MPEG-1 decoder, and host playback application. The CD medium is modified to record video signals as well as digital stereo audio signals. The video information is recorded in analog form rather than digital. CD-V discs contain full-screen, full-motion video and CD-quality audio, and are independent of any broadcast standard, e.g., NTSC, PAL.

Green Book: System Description Compact Disc Read-Only Memory Extended Architecture (CD-ROM/XA)

Orange Book: System Description Compact Disc Systems Part II: (CD-WO)

A digital standard for recordable, write-once CD. The specification covers both disk-at-once and track-at-once. Many older CD-ROM drives cannot read multisession discs, however, these discs can be converted to a Red/Yellow/Green Book disc by adding a TOC, allowing the disc to be read by any CD player. CD Single: A small CD-DA that can record 20 minutes of stereo music; it is 80mm in diameter.

CD-DA: CD-Direct Access. Software for writing audio data on hard disk onto a CD-R, for example, Toast™ or Gear.™ Such packages create an unfinished audio session in disc-at-once mode. Digital audio tracks must first be converted to a computer file format like .WAV or AIFF.CD Extra: Formerly called CD Plus. A solution to mixed-mode CDs, CD Extra inverts the track structure of Mixed Mode by creating two separate sessions: first audio, then data. CD Extra is a part of the Blue Book standard, making Blue Book CDs fully compatible with the Red Book in that Blue Book (data) CDs can be safely used on audio players. The one problem with CD Extra format discs is that its multisession format makes it unusable by first-generation CD-ROM players.CD-I: (CD Interactive) An extension of Yellow book, allowing discs to contain a mix of audio and video, plus data which the user can control interactively. CD-I discs use Mode 2, Form 1 and Mode 2, Form 2 tracks which, like CD-ROM/XA, enable computer data and compressed audio, video, or pictures to be played back at the same time. CD-I tracks cannot be played on normal CD-ROM drives, but specialized CD-I players can play audio CDs, CD+G, Photo CD, and with a CD-V cartridge, Karaoke CD or CD-V discs.CD + MIDI: A type of CD which includes both audio data and MIDI data, i.e., a recording of both the sound of a musical performance, as well as the MIDI data used to generate it. This allows the user to “play with the performance” by choosing different patches, etc. This requires a MIDI Out socket on the CD player.CD-R: See CD.CD Single: A small CD that can record 20 minutes of stereo music; it is 80mm in diameter.CD-V: CD Video. The CD medium modified to record video signals as well as digital stereo audio signals. The video information is recorded in analog form, rather than digital, like a small laser disc.

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