Four Channel Compact Disc Digital Audio is a four channel audio format specified under the Compact Disc Digital Audio Red Book standard. Most compact discs have a diameter of 120 mm and can store 74 minutes of four channel audio. Wikipedia does not have an article with this exact name. ... Size of CD compared to pencil. ... Digital audio describes sound recording and reproduction systems which work by using a digital representation of the audio waveform. ... Rainbow Books: Red Book (CD Digital Audio), Yellow Book (CD-ROM and CD-ROM XA), Orange Book (CD-R and CD-RW), White Book (Video CD), Blue Book (Enhanced Music CD, CD+G and CD-Plus), Beige Book (Photo CD), Green Book (CD-i). ... A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ...

Storing four simultaneous channels of audio instead of the usual two requires appropriately set control bits in CD Subcode channel Q. Since CD players read the disc in a standardized range of constant linear velocity, doubling the number of channels neccessitates halving the amount of data per channel. Thus, a four channel Compact Disc has four channels of 16 bit PCM samples at 22.05 kHz instead of two channels of 16 bit PCM samples at 44.1 kHz. Constant Linear Velocity (CLV) refers to how information is written to or read from a rotating data disk. ... Pulse-code modulation (PCM) is a modulation technique. ... A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ...

Commercial four channel CD releases

Even though the Red Book standard allows for four channel CDs, there are very few mass-marketed releases in this format.

Hardware & software

All CD burners are capable of burning a disc with subcode channel data denoting it as a four channel audio disc. Software to create such an image to be burned is less common. One such application is Cdrdao. A CD burner, CD recorder or CD writer is an internal or external writable Compact Disc drive that can be attached to a computer. ... Cdrdao is open source software for burning compact discs. ...

While four channel audio is part of the Red Book standard [1] (http://developer.apple.com/documentation/Carbon/Reference/discrecording/CarbonDoc/DRCoreTrack/CompositePage.html#kDRAudioFourChannelKey), modern software developers have been discouraged from implementing this feature in CD burning software due to newer and higher fidelity media formats being available, such as Super Audio CD and DVD-Audio. Super Audio CD (SACD) is a new audio recording format aimed at providing higher fidelity audio reproduction than the compact disc. ... DVD is an optical disc storage media format that is used for playback of movies with high video and sound quality and for storing data. ...

See also

• Quadraphonic
• Multichannel audio

Quadraphonic sound uses four channels in which speakers are positioned at all four corners of the listening space, reproducing signals that are independent of each other. ... Multichannel audio refers to the use of multiple sound sources to create a richer, or live music experience. ...

External link

• Cdrdao (http://cdrdao.sourceforge.net/) (Open Source CD burning software)