Super Audio CD Super Audio CD Super Audio CD (SACD) is a read-only optical disc for audio storage, introduced in 1999. It was developed jointly by Sony and Philips Electronics, and intended to be the successor to their Compact Disc (CD) format. While the SACD format can offer more channels (e.g. surround sound), and a longer playing time than CD, research published in 2007 found no significant difference in audio quality between SACD and standard CD at ordinary volume levels. Having made little impact in the consumer audio market, by 2007, SACD was deemed to be a failure by the press. A small
Philips PM5544 the most commonly used test cards, with only the SMPTE bars, the BBC Test Card F and the Snell & Wilcox Zone Plate coming close to its usage. The Philips Pattern was later incorporated into other test pattern generators from Philips themselves, as well as test pattern generators from various other manufacturers. The BBC occasionally used a slightly modified version called Test Card G from 1971 until the late-1990s in conjunction with Test Card F, and although it was also used by the IBA in the 1970s it eventually abandoned the Test Card G and developed its own test card