Super Audio CD
|Media type||Optical disc|
|Read mechanism||650 nm laser|
|Developed by||Sony & Philips|
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 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.
The Super Audio CD format was introduced in 1999. Royal Philips and Crest Digital partnered in May 2002 to develop and install the first SACD hybrid disc production line in the USA, with a production capacity of 3 million discs per year. SACD did not achieve the same level of growth that Compact discs enjoyed in the 1980s, and was not accepted by the mainstream market.
By October 2009, record companies had published more than 6,000 SACD releases, slightly more than half of which were classical music. Jazz and popular music albums, mainly remastered previous releases, were the next two most numerous genres represented.
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.
Between 2007 and 2008, Genesis re-released all their studio albums across three box sets. Each album in these sets contains the original album on SACD in both stereo and 5.1 mixes. The US & Canada versions do not use SACD but CD instead.
By August 2009 443 labels had released one or more SACDs. Instead of depending on major label support, some orchestras and artists have released SACDs on their own. For instance, the Chicago Symphony Orchestra started the Chicago Resound label to provide full support for high-resolution SACD hybrid discs, and the London Symphony Orchestra established their own 'LSO Live' label.
Many of the SACD discs that were released from 2000-2005 are now out of print and are 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.
- Hybrid: Hybrid SACDs are encoded with a 4.7 GB DSD layer (also known as the HD layer), as well as a PCM (Red Book) audio layer readable by most conventional Compact Disc players.
- Single-layer: A DVD-5 encoded with one 4.7 GB DSD layer. Single-layer SACDs are not backward-compatible with conventional CD players.
- Dual-layer: A DVD-9 encoded with two DSD layers, totaling 8.5 GB, and no PCM layer. Dual-layer SACDs can store nearly twice as much data as a single-layer SACD. Like single-layer SACDs, dual-layer discs are not backward-compatible with conventional CD players.
|CD layer (optional)||SACD layer|
|Disc capacity||700 MB||4.7 GB|
|Audio encoding||16 bit PCM||1 bit DSD|
|Sampling frequency||44.1 kHz||2.8224 MHz|
|Audio channels||2 (Stereo)||up to 6 (Discrete surround)|
|Playback time if stereo||80 mins||256 minutes|
Commercial releases commonly included both surround sound (five full-range plus LFE multi-channel) and stereo (dual-channel) mixes on the SACD layer. Some reissues however, retained the mixes of earlier multi-channel formats (examples include the 1973 quadraphonic mix of Mike Oldfield's Tubular Bells and the 1957 three-channel stereo recording by the Chicago Symphony Orchestra of Mussorgsky's Pictures at an Exhibition, reissued on SACD in 2001 and 2004 respectively).
Objective lenses in conventional CD players have a longer working distance, or focal length, than lenses designed for SACD players. This means that when a hybrid SACD is placed into a conventional CD player, the laser beam passes the high-resolution layer and is reflected by the conventional layer at the standard 1.2 mm distance, and the high-density layer is out of focus. When the disc is placed into an SACD player, the laser is reflected by the high-resolution layer (at 0.6 mm distance) before it can reach the conventional layer. Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc as a CD since there is no high-resolution layer.
DSD is 1-bit, has a sampling rate of 2.8224 MHz, and makes use of noise shaping quantization techniques in order to push 1-bit quantization noise up to inaudible ultrasonic frequencies. This gives the format a greater dynamic range and wider frequency response than the CD. The SACD format is capable of delivering a dynamic range of 120 dB from 20 Hz to 20 kHz and an extended frequency response up to 100 kHz, although most currently available players list an upper limit of 70–90 kHz, and practical limits reduce this to 50 kHz. Because of the nature of sigma-delta converters, one cannot make a direct technical comparison between DSD and PCM. DSD's frequency response can be as high as 100 kHz, but frequencies that high compete with high levels of ultrasonic quantization noise. With appropriate low-pass filtering, a frequency response of 20 kHz can be achieved along with a dynamic range of nearly 120 dB, which is about the same dynamic range as PCM audio with a resolution of 20 bits.
To reduce the space and bandwidth requirements of Direct Stream Digital (DSD), a lossless data compression method called Direct Stream Transfer (DST) is used. DST compression is compulsory for multi-channel regions and optional for stereo regions. This typically compresses by a factor of between two and three, allowing a disc to contain 80 minutes of both 2-channel and 5.1-channel sound.
Direct Stream Transfer compression was also standardized as an amendment to MPEG-4 Audio standard (ISO/IEC 14496-3:2001/Amd 6:2005 – Lossless coding of oversampled audio) in 2005. It contains the DSD and DST definitions as described in the Super Audio CD Specification. The MPEG-4 DST provides lossless coding of oversampled audio signals. Target applications of DST is archiving and storage of 1-bit oversampled audio signals and SA-CD. A reference implementation of MPEG-4 DST was published as ISO/IEC 14496-5:2001/Amd.10:2007 in 2007.
SACD has several copy protection features at the physical level, which as of 2012[update] appeared to make the digital content of SACD discs difficult to copy. The content may be copyable without SACD quality by resorting to the analog hole, or ripping the conventional 700 MB layer on hybrid discs. Copy protection schemes include physical pit modulation and 80-bit encryption of the audio data, with a key encoded on a special area of the disk that is only readable by a licensed SACD device. The HD layer of an SACD disc cannot be played back on computer CD/DVD drives, and SACDs can only be manufactured at the disc replication facilities in Shizuoka and Salzburg. 
Sound quality parameters achievable by the Red Book CD-DA and SACD formats compared with the limits of human hearing are as follows:
|Dynamic range||90 dB,
120 dB (with shaped dither)
|105 dB||120 dB|
|Frequency range||20 Hz – 20 kHz||20 Hz – 50 kHz||20 Hz – 20 kHz (young person);
upper limit 8–15 kHz (middle-aged adult)
Comparison with CD
In the audiophile community, the sound from the SACD format is thought to be significantly better than that of CD. For example, one supplier claims that "The DSD process used for producing SACDs captures more of the nuances from a performance and reproduces them with a clarity and transparency not possible with CD.
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 SACD 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:
Now, it is very difficult to use negative results to prove the inaudibility of any given phenomenon or process. There is always the remote possibility that a different system or more finely attuned pair of ears would reveal a difference. But we have gathered enough data, using sufficiently varied and capable systems and listeners, to state that the burden of proof has now shifted. Further claims that careful 16/44.1 encoding audibly degrades high resolution signals must be supported by properly controlled double-blind tests.
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.
Comparison with DVD-A
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. Despite both formats' extended frequency responses, it has been shown people cannot distinguish audio with information above 21 kHz from audio without such high-frequency content.
The Sony SCD-1 player was introduced concurrently with the SACD format in 1999, at a price of approximately US$5,000. It weighed over 26 kg (57 lb) and played two-channel SACDs and Red Book CDs only. Electronics manufacturers, including Onkyo, Denon, Marantz, Pioneer and Yamaha offer or offered SACD players. Sony has made in-car Super Audio CD players.
The first two generations of Sony's PlayStation game console were capable of reading SACD discs. Starting with the third generation (introduced October 2007), SACD playback was removed. All PS3 models however will play DSD Disc format. PS3 was capable of converting multi-channel DSD to lossy 1.5 Mbit/s DTS for playback over S/PDIF using the 2.00 system software. The subsequent revision removed the feature.
Unofficial playback of SACD disk images on a PC is possible through freeware audio player foobar2000 for Windows using an open source plug-in extension called SACDDecoder. Mac OS X music software Audirvana also supports playback of SACD disk images.
- Audio format
- Audio storage
- Earlier attempts at higher fidelity that stayed within the CDDA standard: HDCD and XRCD.
- Later attempts at higher fidelity that stayed within the CDDA standard: Blu-spec CD, DSD-CD and SHM-CD.
- Meyer, E. Brad and Moran, David R. "Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback". AES E-Library 55 (9): 775–779.
- The Guardian, Thursday 2 August 2007 No taste for high-quality audio by Jack Schofield. "Such a format—Super Audio CD (SACD)—has been out there since September 1999. And now, it's dying." Retrieved on May 29, 2009.
- "The 10 Best Audiophile SACDs Ever - Many Are Out Of Print". Audiophilereview.com. Retrieved 2013-03-06.
- "Crest National and Philips Partner to Bring SACD Hybrid Disc Manufacturing to the USA". Newscenter.philips.com. 2002-05-30. Retrieved 2011-12-31.
- Mark Fleischmann Are DVD-Audio and SACD DOA? April 2, 2004 "the CD tidal wave was so aggressive that it swept away everything in its path including the terms album and record. I keep waiting for a high-resolution audio to trigger a similar tsunami. But tiny islands of SACDs and DVD-Audio titles in my local Tower Records have not grown into mighty continents."  Retrieved on January 16, 2010.
- C|Net News, March 26, 2009 Betamax to Blu-ray: Sony format winners, losers by Steve Guttenberg.  "SACD was praised by audiophiles, but fizzled in the market. Sony Records no longer releases new SACD titles" (This is not entirely true; while Sony Classical does not appear to be making new SACD releases, Sony Classical in Germany and Japan made SACDs as recently as June 5, 2009 Sony Classical Germany Sony Music Japan) Retrieved on May 29, 2009.
- Stereofile eNewsletter, January 10, 2006. Io Saturnalia! by Wes Phillips.  Mentions "the failure of SACD and DVD-A to gain traction." Retrieved on May 28, 2009.
- Audio Video Revolution, October 19, 2006. The Symbolism Of Losing Tower Records by Jerry Del Colliano. "The pure failure of SACD and DVD-Audio as high resolution formats was analogous burning down a small town."  Retrieved on May 28, 2009.
- High Fidelity Review. News. Retrieved on May 20, 2009.
- High Fidelity Review. Universal Music Artists Hit SACD Gold and Silver in Europe. Retrieved on May 18, 2009.
- SA-CD.net. FAQ
- Chicago Resound label retrieved June 6, 2009
- London Symphony Orchestra – Buy Recordings retrieved June 6, 2009
- Sinclair, Paul (January 30, 2013). "Top 10: SACDs you can afford to buy". Retrieved 2013-03-11.
- Guttenberg, Steve (July 16, 2009). "Are SACD and DVD-Audio dead yet?". CNET. Retrieved 2013-03-11.
- Extremetech.com, Leslie Shapiro, July 2, 2001. Surround Sound: The High-End: SACD and DVD-Audio. "A stereo SACD recording has a data rate of 5.6Mbps, which is four times the stereo CD data rate of 1.4Mbps." Retrieved on May 20, 2009.
- PC Magazine Encyclopedia Definition of Hybrid SACD Retrieved June 16, 2009
- Middleton, Chris; Zuk, Allen (2003). The Complete Guide to Digital Audio: A Comprehensive Introduction to Digital Sound and Music-Making. Cengage Learning. p. 54. ISBN 1592001025.
- Clifford, Martin (1987). "The Complete Compact Disc Player." Prentice Hall. p. 57. ISBN 0-13-159294-7.
- Amazon.com Tubular Bells Hybrid SACD "a pristine condition four-channel master of this legendary recording" Retrieved June 3, 2009
- ArkivMusic.com, Album Details: Mussorgsky: Pictures At An Exhibition, Etc / Reiner, Chicago "The three-channel remastering is equally successful" Retrieved June 3, 2009
- How A Hybrid Super Audio Compact Disc (SACD) Works "SACD players are equipped with optical pick-ups that emit a 650 nanometer wavelength laserlight that is reflected by the DSD layer. The optical pick-ups in all CD players, however, emit a 780 nanometer laserlight which is transparent to the DSD layer, so only the CD layer is read" Retrieved June 16, 2009
- Reefman, Derk; Nuijten, Peter. "Why Direct Stream Digital is the best choice as a digital audio format." (PDF) Audio Engineering Society Convention Paper 5396, May 2001.
- Ambisonic.net. Richard Elen, August 2001. Battle of the Discs. Retrieved on May 20, 2009.
- practical-home-theater-guide.com Direct Stream Digital Technology Retrieved June 3, 2009
- ISO/IEC (2006-03-14). "ISO/IEC 14496-3:2001/Amd 6:2005 – Lossless coding of oversampled audio". ISO. Retrieved 2009-10-09.
- ISO/IEC (2007-08-06). "ISO/IEC 14496-4:2004/Amd 15:2007 – Lossless coding of oversampled audio". ISO. Retrieved 2009-10-09.
- ISO/IEC JTC1/SC29/WG11/N6674 (July 2004), ISO/IEC 14496-3:2001/FPDAM6 (Lossless coding of oversampled audio). (DOC), retrieved 2009-10-09
- ISO/IEC JTC 1/SC 29/WG 11 N7465 (July 2005). "Description Lossless coding of oversampled audio". chiariglione.org. Retrieved 2009-10-09.
- ISO/IEC JTC 1/SC 29/WG 11 N7465 (July 2005). "Description Lossless coding of oversampled audio". archive.org. Archived from the original on 2007-02-03. Retrieved 2009-12-28.
- ISO/IEC (2009-09-01), ISO/IEC 14496-3:2009 – Information technology – Coding of audio-visual objects – Part 3: Audio (PDF), IEC, retrieved 2009-10-07
- ISO/IEC (2007), ISO/IEC 14496-5:2001/Amd.10:2007 – Information technology – Coding of audio-visual objects – Part 5: Reference software – Amendment 10: SSC, DST, ALS and SLS reference software (ZIP), ISO, retrieved 2009-10-07
- ISO/IEC (2007-03-01), ISO/IEC 14496-5:2001/Amd.10:2007 – SSC, DST, ALS and SLS reference software, ISO, retrieved 2009-10-09
- "Sony Starts Hybrid Super Audio CD Production Facilities in Europe". SA-CD.net. 2003-01-22. Retrieved 2007-07-12.
- "Details of DVD-Audio and SACD". DVDdemystified.com. Retrieved 2007-07-12.
- Fries, Bruce; Marty Fries (2005). Digital Audio Essentials. O'Reilly Media. p. 147. ISBN 0-596-00856-2.
- http://xiph.org/~xiphmont/demo/neil-young.html “With use of shaped dither ... the effective dynamic range of 16 bit audio reaches 120dB in practice”
- Rossing, Thomas (2007). Springer Handbook of Acoustics. Springer. pp. 747,748. ISBN 978-0387304465.
- "What are the benefits of SACD?" Mariinsky Label FAQ" Retrieved January 1, 2014.
- Galo, Gary (2008). "Is SACD doomed?". Audioxpress.com. Retrieved November 6, 2012.
- Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback. Audio Engineering Society, September 2007.
- Paul D. Lehrman: The Emperor's New Sampling Rate Mix online, April 2008.
- Blech, Dominikp; Yang, Min-Chi. "DVD-Audio versus SACD: Perceptual Discrimination of Digital Audio Coding Formats." (PDF) Audio Engineering Society Convention Paper 6086, May 2004.
- "The 1-Bit Advantage – Future Proof Recording" (PDF). Korg. Retrieved 2011-12-31.
- Toshiyuki Nishiguchi, Kimio Hamasaki, Masakazu Iwaki, and Akio Ando, "Perceptual Discrimination between Musical Sounds with and without Very High Frequency Components"  Published by NHK Laboratories in 2004
- "The Sony SCD-1 SACD Player". @udiophilia. Retrieved 2006-05-18.
- Onkyo's list of CD Players shows a single SACD player, the C-S5VL. Retrieved March 21, 2012
- Denon's web page shows a single SACD player, the DCD-SA1. Retrieved June 3, 2009
- Marantz's list of Hi-Fi Components shows one SACD player and Marantz's "Reference series" list shows four SACD players. Retrieved June 3, 2009
- The PD-D6-J and PD-D9-J are two SACD players that Pioneer offers. Retrieved June 3, 2009
- Yamaha's web page shows the CD-S1000 and CD-S2000 SACD players. Retrieved June 3, 2009
- "Sony Announces Three Super Audio CD Car Stereo Players". High Fidelity Review. Archived from the original on 2007-03-02. Retrieved 2007-01-18.
- practical-home-theater-guide.com SACD Playback Requirements and Content Protection "SACD compatible players are not permitted to send DSD digital content over an unencrypted digital audio link" Retrieved June 18, 2009
- "Why did Sony take SA-CD out of PS3 again?". PS3 SACD FAQ. Retrieved 2009-01-04.
- "Firmware v2.01". PS3SACD.com. November 22, 2007. Retrieved August 11, 2010.
- "Super Audio CD-compatible Blu-ray Disc players". Retrieved 2009-10-21.
- Maxim V. Anisiutkin. "Super Audio CD Decoder". SourceForge. Retrieved 18 March 2012.
- "Audirvana Plus". Audirvana. Retrieved 26 November 2013.
- Janssen, E.; Reefman, D. "Super-audio CD: an introduction". Signal Processing Magazine, IEEE Volume 20, Issue 4, July 2003, pp. 83–90.
- Super Audio Compact Disc: A Technical Proposal, Sony (archived PDF)
- SA-CD.net Reviews of SACD releases and a discussion forum.
- SA-CD Faq
- New SACD releases Sony website, in Japanese.