SACD
Short for Super Audio CD, SACD is a special type of audio disc that is read-only and capable of holding more audio play time than a standard CD (compact disc). Audio can be encoded in stereophonic or surround sound, providing for higher sound quality than a standard audio CD. The SACD is the same physical size as a standard CD, but has the density of a single or dual-layer DVD (digital versatile disc).
Introduced in 1999, Sony and Philips Electronics developed the SACD as a joint effort. The SACD features a sampling rate of up to 2.8224 MHz, which is 64 times faster than a standard audio CD. SACD also streams audio data at an uncompressed rate of 5.6 Mbit/s. A hybrid SACD can play in a standard CD player, but not all SACDs are available with a hybrid layer.