The logical format of an audio CD (officially Compact Disc Digital Audio or CD-DA) is described in a document produced in 1980 by the format's joint creators, Sony and Philips. The document is known colloquially as the Red Book CD-DA after the colour of its cover. The format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel. Four-channel sound was to be an allowable option within the Red Book format, but has never been implemented. Monaural audio has no existing standard on a Red Book CD; thus, mono source material is usually presented as two identical channels in a standard Red Book stereo track (i.e., mirrored mono); an MP3 CD, however, can have audio file formats with mono sound. COUNT 4
QSN1 Where does the Red Book get it's name from? ANS1 the colour of its cover QSN2 What is the formal name for a CD?  ANS2 Compact Disc Digital Audio QSN3 Do CDs have a two or four channel format? ANS3 two-channel QSN4 What format has never been implemented on CDs? ANS4 Four-channel sound