sacd

Super Audio CD (SACD) is a read-only optical disc format for audio storage, introduced in 1999. It was developed jointly by Sony and Philips Electronics, and intended to be the successor to the Compact Disc (CD) format.
The SACD format offers more audio channels (e.g. surround sound), a higher bit rate, and longer playing time than a conventional CD. The SACD is designed to be played on an SACD player; however, a hybrid SACD contains a Red Book Compact Disc Digital Audio (CDDA) layer which can be played on a standard CD player.

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