Super Audio CD

The Super Audio CD format was introduced in 1999, and is defined by the Scarlet Book standard document. Philips and Crest Digital partnered in May 2002 to develop and install the first SACD hybrid disc production line in the United States, with a production capacity of up to three million discs per year. SACD did not achieve the level of growth that compact discs enjoyed in the 1980s, and was not accepted by the mainstream market. By 2007, SACD had failed to make a significant impact in the marketplace; consumers were increasingly downloading low-resolution music files over the internet rather than buying music on physical disc formats. A small and niche market for SACD has remained, serving the audiophile community. == Content ==

Many popular artists have released some or all of their back catalog on SACD. Pink Floyd's album The Dark Side of the Moon (1973) sold over 800,000 copies by June 2004 in its SACD Surround Sound edition. The Who's rock opera Tommy (1969), and Roxy Music's Avalon (1982), were released on SACD to take advantage of the format's multi-channel capability. All three albums were remixed in 5.1 surround, and released as hybrid SACDs with a stereo mix on the standard CD layer. Some popular artists have released new recordings on SACD. Sales figures for Sting's Sacred Love (2003) album reached number one on SACD sales charts in four European countries in June 2004. Between 2007 and 2008, the rock band Genesis re-released all of their studio albums across three SACD box sets. Each album in these sets contains both new stereo and 5.1 mixes. The original stereo mixes were not included. The US and Canada versions do not use SACD but CD instead. By August 2009, 443 labels had released one or more SACDs. Many SACD discs that were released from 2000 to 2005 are now out of print and available only on the used market. By 2009, the major record companies were no longer regularly releasing discs in the format, with new releases confined to the smaller labels. == Technology ==

SACD discs have identical physical dimensions as standard compact discs. The areal density of the disc is the same as a DVD. There are three types of disc: and certain Blu-ray players can use specialized software to extract a DSD copy of the HD stream. == Sound quality ==

Sound quality parameters achievable by the Red Book CD-DA and SACD formats compared with the limits of human hearing are as follows: ; CD: Dynamic range: 90 dB; 120 dB (with shaped dither); frequency range: 20 Hz20 kHz ; SACD: Dynamic range: 105 dB; frequency range: 20 Hz50 kHz ; Human hearing: Dynamic range: 120 dB; frequency range: 20 Hz20 kHz (young person); 20 Hz8–15 kHz (middle-aged adult) In September 2007, the Audio Engineering Society published the results of a year-long trial, in which a range of subjects—including professional recording engineers—were asked to discern the difference between high-resolution audio sources (including SACD and DVD-Audio) and a compact disc audio (44.1 kHz/16 bit) conversion of the same source material under double-blind test conditions. Out of 554 trials, there were 276 correct answers, a 49.8% success rate corresponding almost exactly to the 50% that would have been expected by chance guessing alone. When the level of the signal was elevated by 14 dB or more, the test subjects were able to detect the higher noise floor of the CD-quality loop easily. The authors commented: Following criticism that the original published results of the study were not sufficiently detailed, the AES published a list of the audio equipment and recordings used during the tests. Since the Meyer–Moran study in 2007, approximately 80 studies have been published on high-resolution audio, about half of which included blind tests. Joshua Reiss performed a meta-analysis on 20 of the published tests that included sufficient experimental detail and data. In a paper published in the July 2016 issue of the AES Journal, Reiss says that, although the individual tests had mixed results, and that the effect was "small and difficult to detect," the overall result was that trained listeners could distinguish between high-resolution recordings and their CD equivalents under blind conditions: "Overall, there was a small but statistically significant ability to discriminate between standard-quality audio (44.1 or 48 kHz, 16 bit) and high-resolution audio (beyond standard quality). When subjects were trained, the ability to discriminate was far more significant." Hiroshi Nittono pointed out that the results in Reiss's paper showed that the ability to distinguish high-resolution audio from CD-quality audio was "only slightly better than chance." Contradictory results have been found when comparing DSD and high-resolution PCM formats. Double-blind listening tests in 2004 between DSD and 24-bit, 176.4 kHz PCM recordings reported that among test subjects no significant differences could be heard. DSD advocates and equipment manufacturers continue to assert an improvement in sound quality above PCM 24-bit 176.4 kHz. A 2003 study found that despite both formats' extended frequency responses, people could not distinguish audio with information above 21 kHz from audio without such high-frequency content. In a 2014 study, however, Marui et al. found that under double-blind conditions, listeners were able to distinguish between PCM (192 kHz/24 bits) and DSD (2.8 MHz) or DSD (5.6 MHz) recording formats, preferring the qualitative features of DSD, but could not discriminate between the two DSD formats. == Playback hardware ==

In 1999, the Sony SCD-1 player was introduced concurrently with the SACD format, at a price of approximately US$5,000 (). or more commonly, HDMI. SACD players are not permitted to offer an output carrying an unencrypted stream of DSD. macOS music software Audirvana also supports playback of SACD disc images. == See also ==