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Direct Stream Digital

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Direct Stream Digital
DSD logo
Media type
  • Audio recording process
  • Disc format
EncodingDigital
Read mechanismDSD
Write mechanismSuper Audio CD
StandardISO/IEC 14496-3
UsageAudio recording
Extended topresent
Released1999

Direct Stream Digital (DSD) is a trademark used by Sony and Philips for their system for digitally encoding audio signals for the Super Audio CD (SACD).

DSD uses delta-sigma modulation, a form of pulse-density modulation encoding, a technique to represent audio signals in digital format, a sequence of single-bit values at a sampling rate of 2.8224 MHz. This is 64 times the CD audio sampling rate of 44.1 kHz, but with 1-bit samples instead of 16-bit samples. Noise shaping of the 64-times oversampled signal provides low quantization noise and low distortion in the audible bandwidth necessary for high resolution audio.

DSD is simply a format for storing a delta-sigma signal without applying a decimation process that converts the signal to a PCM signal.

Development

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DSD technology was developed and commercialized by Sony and Philips, the designers of the audio CD. However, in 2005, Philips sold its DSD tool division to Sonic Studio.[1][better source needed]

Major label support

DVD-Audio was endorsed by the Warner Music Group, while the SACD format was endorsed by Sony and Universal Music Group, with an especially high-profile by UMG imprint Virgin Records.[2][3] Despite this, in 2011, The Warner Premium Sound series of albums was released by Warner Music Group, marking the first time the label released titles in a SACD format, with recording in DSD.[4] The series grew to ten rock and pop albums, with Super Audio CD/CD hybrid discs containing both an SACD layer and a standard CD layer.[5]

Sony did not promote SACD actively in North America, with the result that DVD-Audio gained competitive traction in the market. Elsewhere, such as in Europe or Japan, SACD gained more of a foothold.[6] Examples include the German Stockfisch Records, which releases vinyl editions of albums and DSD-recordings, released as hybrid SACDs.[7]

Independent label use

Music companies that specialize in Super Audio CD products therefore use DSD encoding. A number of independent record labels have also worked directly with Sony to focus on DSD products or the DSD recording process.

DMP Digital Music Products was an early user of the SACD digital audio format.[8] In 1997 their release Alto by Joe Beck & Ali Ryerson was the first commercial recording captured with Sony's DSD recording technology. The label's Just Jobim by Manfredo Fest in 1998 was the first project captured with the new Meitner DSD conversion technology. In 2000, DMP released the world's first multi-channel SACD—Sacred Feast by Gaudeamus.[9]

The majority of Telarc International Corporation's releases were on (generally hybrid) SACD, and are DSD recordings.[10][failed verification] Telarc often worked with early audiophile company Soundstream, and re-released many of its original Soundstream recordings in SACD format.[11] Soundstream, which made the first digital recording in the United States, recorded in 16-bit PCM at a sample rate of 50 kHz via its own proprietary digital recorder. This 50 kHz PCM format was converted to DSD for release on Telarc SACD.

The record label Mobile Fidelity had engineers who decided to adopt the SACD over the DVD-Audio disc as a favored high-resolution digital format after listening tests and technical evaluations. On the label's Hybrid SACD releases, the SACD layer is a direct DSD recording of the analog master tape, while the CD layer is a digital down conversion of the DSD, with Super Bit Mapping applied. Post-2001, CD-only releases are sourced from DSD, but omit the SACD layer.[12]

In 2007, Blue Coast Records was founded in California for the purpose of recording and releasing music recorded with the DSD format, primarily focusing on jazz and acoustic artists.[13]

On August 28, 2013, the Acoustic Sounds label launched SuperHiRez.com (now defunct), which sold mainstream albums from major record labels that were produced with Direct Stream Digital or PCM audio formats.[14][15] On September 4, 2013, Acoustic Sounds announced an agreement with Sony Music Entertainment to provide the company's new digital download service with albums that have been produced or remastered in DSD format.[16]

The format is used on albums such as Pop, Songs & Death in 2009,[17] and the remastered The Rolling Stones album Their Satanic Majesties Request in 2002.[18][19]

DSD signal format

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Comparison with PCM

DSD differs from the PCM format used by compact disc or typical computer audio systems: while PCM uses a multi-bit value (representing a large range of amplitudes) at a low sample rate, DSD instead uses a single-bit value (representing an increase or decrease in amplitude) at a sample rate much higher than the signal's bandwidth.

The process of creating a DSD signal is the same as the front-end modulator and noise-shaper portion of a 1-bit delta-sigma analog-to-digital converter (ADC), without the back end decimator (which would typically convert the 1-bit bitstream into multi-bit PCM). The short-term average of the 1-bit DSD bitstream signal is proportional to the original signal amplitude. Because of the higher sample rate, an SACD player can use a one-bit DAC with a low-order analog filter to reconstruct and produce the analog output.

DSD uses noise shaping techniques to push quantization noise up to inaudible ultrasonic frequencies. Because of this, single rate DSD64 can deliver a dynamic range of 120 dB from 20 Hz to 20 kHz and an extended frequency response up to 100 kHz (most recent SACD players specify an upper limit of 80 to 90 kHz).[citation needed]

The various DSD formats use sampling rates well into the megahertz (MHz) range, typically with an oversampling ratio that is a power of two relative to the 44.1 kHz rate used for CD audio:

Name Abbreviation Sample rate Oversampling ratio relative to 44.1 kHz Notes
Single-rate DSD DSD64 2.8224 MHz 64x The format used for SACD media.
Double-rate DSD DSD128 5.6448 MHz 128x Since its establishment, content creators have made DSD128 recordings available, such as the audiophile label Opus3.[20]
Quad-rate DSD DSD256 11.2896 MHz 256x
Octuple-rate DSD DSD512 22.5792 MHz 512x
Sexdecuple-rate DSD DSD1024 45.1584 MHz 1024x

See delta-sigma modulation § Theoretical effective number of bits for analysis of the effective number of bits that can be achieved by oversampling, especially when using a higher order modulator.

DSD mixing and mastering

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DSD music mixing and mastering for SACD or Internet download presents challenges due to the difficulty of performing digital signal processing (DSP) operations (such as equalization, balance, panning) in a one-bit environment.

Older analog recordings were processed using analog equipment and then digitized to DSD. It is also possible to avoid processing by using only the available adjustments in the studio equipment while recording to DSD.

One DSP technique available is to convert the DSD to PCM and use standard PCM equipment such as Pro Tools, useful for rock and contemporary music which rely on multitrack techniques, then digitally convert back to DSD format. Some DSD proponents dislike this technique claiming that the PCM conversion to a lower sample rate reduces the sound quality of DSD.

A format and set of tools for PCM processing of DSD has been developed under the name Digital eXtreme Definition (DXD). This is a PCM format with 24-bit resolution sampled at 352.8 kHz. Another DSP technique uses a format commonly referred to as DSD-wide, which retains the high sample rate of standard DSD, but uses 8-bit samples with noise shaping. DSD-wide is sometimes disparagingly referred to as PCM-narrow. It has the benefit of making DSP operations practical while retaining the 2.8224 MHz sampling frequency. The processed DSD-wide signal is converted to the final 1-bit DSD product at the same sample rate. Processing DSD-wide at the higher multiple-DSD sample rates is also possible. Pyramix and some SADiE digital audio workstation (DAW) systems can operate in the DSD-wide domain.[citation needed]

DSD processing tools

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DXD was initially developed for the Merging Technologies Pyramix workstation and introduced together with their Sphynx 2, AD/DA converter in 2004. This combination meant that it was possible to record and edit directly in DXD,[21] and that the sample only converts to DSD once before publishing. This offers an advantage to the user as the noise created by converting DSD rises dramatically above 20 kHz, and more noise is added each time a signal is converted back to DSD during editing.

The Pyramix Virtual Studio Digital Audio Workstation allows for recording, editing and mastering all DSD formats up to DSD256. A 12.288 MHz DSD256 variant based on a 48 kHz reference[a] is supported. The exaSound e20 DAC was the first commercially available device capable of DSD256 playback at sampling rates of 11.2896 or 12.288 MHz.[22][23] The Merging Technologies Horus AD/DA Converter offers sample rates up to 11.2 MHz, or four times the SACD rate.

DSD128, 5.6448 MHz, twice the SACD rate, has been supported by multiple hardware devices such as the exaSound e20 Mk II DA,C[24] Korg MR-1000 1-bit digital recorder, Amanero Combo384 DSD output adapter and the discontinued exaU2I USB to I²S interface.

Software supporting DSD includes Sonic Studio's Amarra Luxe, Audirvana, foobar2000 with SACD plugin, JRiver Media Center, Roon,[25] HQPlayer and Neutron Music Player are all able to handle DSD files of up to DSD512 rate fully natively.

DSD playback options

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Sony developed DSD for SACD, and many disk players support SACD. Since the format is digital, there are other ways to play back a DSD stream; the development of these alternatives has enabled companies to offer high-quality music downloads in DSD.[26]

DSD disc format

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Some professional audio recorders (from Korg, Tascam, and others) can record in DSD format. Transferring this signal to a recordable DVD with the appropriate tools, such as the AudioGate software bundled with Korg MR-2000S recorder,[27] renders a DSD Disc. Such discs can be played back in native DSD only on certain Sony VAIO laptops and PlayStation 3 systems.[28] Sony produced two SACD players, the SCD-XA5400ES and the SCD-XE800, that fully support the DSD-disc format. In June 2012, Pioneer launched a series of SACD players compatible with DSD-disc. The PD-30 and PD-50. In January 2013, TEAC announced a DSD-disc compatible player, the PD-501HR.[29]

DSD over USB

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An alternative to burning DSD files onto disks for eventual playback is to transfer the (non-encrypted) files from a computer to audio hardware over a digital link such as USB. The USB audio 2.0 specification defined several formats for the more common PCM approach to digital audio, but did not define a format for DSD.

In 2012, representatives from many companies and others developed a standard to represent and detect DSD audio within PCM frames; the standard, commonly known as DSD over PCM (DoP), is suitable for other digital links that use PCM.[30] The 1.1 revision added protocol support for higher DSD sample rates without requiring an increase the underlying PCM sample rate.

Native DSD

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The definition of native DSD playback is somewhat a matter of philosophy. Generally speaking, it avoids the conversion of DSD data into multibit PCM anywhere along the reproduction chain.[citation needed] Many commercially available DACs now support native DSD.

DSD vs. PCM

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There has been much controversy between proponents of DSD and PCM over which encoding system is superior. In 2000, Lipshitz and Vanderkooy stated that one-bit converters, as employed by DSD, are unsuitable for high-end applications due to their high distortion.[31][32] In 2002, Philips published a paper arguing the contrary.[33] Lipshitz and Vanderkooy's paper was further criticized by Angus.[34] Lipshitz and Vanderkooy responded to the criticisms.[35] Stuart also defined sigma-delta modulation a "totally unsuitable choice" for high-resolution digital audio.[36]

Conventional implementation of DSD has an intrinsic high distortion.[37] Distortion can be alleviated to some degree by using multibit DACs. State-of-the-art ADCs are based around sigma-delta modulation designs. Oversampling converters are usually used in linear PCM formats, where the ADC or DAC output is subject to bandlimiting and dithering.[38] Most modern ADC and DAC converters use oversampling and a multi-bit design; in other words, while DSD is a 1-bit format, modern converters internally use a 2-bit[39] to 6-bit[40] format.

Comparisons of DSD and PCM recordings with the same origin, number of channels and similar bandwidth and noise have yielded contradictory results. A 2004 study conducted at the Erich-Thienhaus Institute in Detmold, Germany found that in double-blind tests "hardly any of the subjects could make a reproducible distinction between the two encoding systems."[41] In contrast, a 2014 study conducted at the Tokyo University of the Arts found that listeners could distinguish PCM (192 kHz/24 bits) from either DSD (2.8 MHz) or DSD (5.6 MHz) (but not between the two DSD samplings), preferring the sound of DSD over PCM: "For example, Drums stimulus of DSD (5.6 MHz) has p = 0.001 when compared against PCM (192 kHz/24 bit) in overall preference. This suggests that DSD version was statistically significantly preferred over the PCM version."[42] These findings are questionable however, because "the two formats were subject to different processing, most notably, different filtering of the low-frequency content."[43]

Even though DSD-based SACD was more successful than its direct competitor, the PCM-based DVD-Audio, DSD met with relatively little success in the consumer market. Direct manipulation of recorded DSD data is difficult due to the limited availability of appropriate software. The advent of new high-resolution PCM standards, such as DXD, further restricted DSD's market niche.

DSD file formats

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There are several ways to store DSD encoded audio as files on a computer. One option is to use DSD native file formats used specifically for this purpose. Alternatively, DSD can be stored in general purpose audio formats officially adapted to support DSD storage. Finally, DSD audio can be embedded into PCM audio streams that do not have special DSD support. However, a special decoder is needed to recover the DSD stream from these PCM files.

DSD Interchange File Format

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DSD Interchange File Format
Filename extension
.dff
Internet media type
audio/x-dff
Developed byPhilips
Latest release
1.5
2004-27-04
Type of formatDSD Audio
Websitesonicstudio.com/pdf/dsd/DSDIFF_1.5_Spec.pdf

DSD Interchange File Format (DSDIFF) is a native DSD file format developed by Philips between 2000 and 2004 for storage of DSD recordings.[44] The format supports DST compression of the payload as well as annotations used in Super Audio CD production. A single DSDIFF file may store an entire album as a single audio stream together with markers indicating the location of individual tracks for the album. Some parts of the audio content may be left out entirely from the resulting SACD. The embedded metadata format is intended for mastering engineers not consumers. For example, markers indicating the beginning of a new audio track have a text field for storing arbitrary text-based information. However, there is no requirement for the text to contain the title of the track. A de facto standard for including ID3 metadata in an unofficial ID3 chunk was later developed as consumers adopted the format for storing individual tracks of DSD audio. DSDIFF files typically use the .dff file suffix. No official media type has been registered for the DSDIFF file format.[45] Freedesktop.org uses the unofficial media types audio/x-dff.[46]

Wideband Single-bit Data

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Wideband Single-bit Data
Filename extension
.wsd
Internet media typeaudio/x-dsf
Developed by1-bit Audio Consortium
Type of formatDSD Audio

Wideband Single-bit Data (WSD) is a native DSD file format developed by 1-bit Audio Consortium in 2002.[47] The consortium was established by Waseda University, Sharp and Pioneer a year earlier.[48] In 2012 the consortium published an updated 1.1 version of the specification.[49] The WSD header has a field for storing an absolute timestamp in samples since midnight. The timestamp makes it possible to accurately know how much time passed between two recordings made consecutively on the same physical recording device. Korg portable recorders MR-1, MR-2, MR-1000 and MR-2000s support WSD alongside other DSD based formats.[50][51][52]

DSD Stream File

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DSD Stream File
Filename extension
.dsf
Internet media type
audio/x-dsf
Developed bySony
Latest release
1.01
November 2005
Type of formatDSD Audio
Websitedsd-guide.com/sonys-dsf-file-format-spec

DSD Stream File (DSF) is a native DSD file format developed by Sony around 2005.[53][54] The format is intended for storing individual tracks of DSD audio and has native support for ID3 metadata inclusion. The format defines a "format ID" field that could presumably be used to indicate DST compression. However, the only identifier defined in the spec is number 0 indicating "DSD raw". Files containing DSF data would typically use the.dsf file suffix. No official media type has been registered for the DSF file format.[45] Freedesktop.org uses the unofficial media types audio/x-dsf.[46]

DSD compatible file formats

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DSD-compatible file formats support storing DSD-encoded audio in addition to audio encoded as PCM.

WavPack is a generic audio storage format supporting various different forms of audio.[55] Compressed DSD audio is also supported by the format.[56] The DSD support was initially introduced with the release of WavPack software suite version 5 in December 2016.[57] Files containing WavPack data would typically use the.wv file suffix. No official media type has been registered for the WavPack file format.[45] Freedesktop.org uses the unofficial media types audio/x-wavpack.[46] Since WavPack supports multiple formats, the suffix or mime type alone does not indicate the presence of DSD audio.

DSD over PCM (DoP)

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In addition to actual DSD file formats, a format called DSD Audio over PCM Frames (DoP) is used for embedding DSD into PCM audio streams.[58] DoP makes it possible to circumvent any PCM-only component in the playback chain that would prevent a DSD-capable DAC from receiving the raw DSD data required for native DSD playback. While DoP is intended to be a wire protocol used for communication between music player application and a DAC, there exists tools that can embed DoP-encoded DSD into FLAC files enabling users to use a non-DSD capable player for DSD playback with their DoP-capable DAC.[59] A DoP stream is designed to sound like low-volume noise when played back by a PCM-only DAC, while a DoP-capable DAC will detect the presence of DSD data, extract it from the PCM and play it back as DSD.

See also

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Notes

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  1. ^ 48 kHz × 256 = 12.288 MHz as opposed to the more common 44.1 kHz × 256 = 11.2 MHz

References

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  1. ^ "Sonic Studio Takes Over Philips ProTech DSD i SACD Products [HFR]". HighFidelityReviews. July 9, 2005. Retrieved October 27, 2018.
  2. ^ Davis, Nick. "Genesis on SACD: Nick Davis interview" (Interview). Interviewed by Christian Gerhardts. Retrieved November 3, 2011.
  3. ^ "Genesis Reviews | SACD". Retrieved October 27, 2018.
  4. ^ Marchese, Joe (July 15, 2011). "Eagles, Deep Purple, Yes! Out-Of-Print DVD-Audios Coming To SACD". The Second Disc. Retrieved November 3, 2011.
  5. ^ "Ultradisc UHR SACD". Mobile Fidelity. Archived from the original on October 28, 2018. Retrieved October 27, 2018.
  6. ^ "March 30". DVD-A.net. March 30, 2008. Retrieved October 27, 2018. In Europe and some other parts of the world this was done using the SACD format but not in North America, like with other reissues (such as the Depeche Mode albums).
  7. ^ "A new format: The Stockfisch DMM-CD/SACD". Stockfisch Records. February 5, 2016. Retrieved October 27, 2018.
  8. ^ Jung, Tom (June 27, 2004). "Tom Jung of DMP: Making Musical Sense". Stereophile Magazine (Interview). Interviewed by David Lander. Retrieved October 27, 2018.
  9. ^ "Gaudeamus – Sacred Feast". Discogs. Retrieved October 27, 2018.
  10. ^ "Official site". Archived from the original on January 14, 1998. Retrieved January 6, 2015.
  11. ^ Renner, Jack (Fall 1992), "The Roots of Telarc", Telarc newsletter
  12. ^ "Enjoy the Music". Retrieved November 12, 2010.
  13. ^ Rick Clark (May 1, 2004). "5.1 Recording Vibes With ESE". Mix. Archived from the original on December 3, 2013. Retrieved November 19, 2013.
  14. ^ Brockhouse, Gordon (August 28, 2013). "Acoustic Sounds Launches Hi-Res Download Service". MarketNews. Archived from the original on September 4, 2013. Retrieved October 27, 2018.
  15. ^ Snider, Mike (August 28, 2013). "Kansas firm raises bar on high-res music downloads". USA TODAY.
  16. ^ Lavorgna, Michael (September 4, 2013). "Acoustic Sounds Announces DSD Deal with Sony Music!". AudioStream. Retrieved October 27, 2018.
  17. ^ "Wheatus' new record downloadable in DSD". PS3SACD.com. July 24, 2009. Archived from the original on September 29, 2018. Retrieved October 27, 2018.
  18. ^ Walsh, Christopher (August 24, 2002). "The Rolling Stones Remastered - Super Audio CDs". Billboard. p. 27.
  19. ^ "Rolling Stones Turn To 'Super Audio' For Reissues". Billboard. May 30, 2002. Retrieved October 27, 2018.
  20. ^ Hiro (April 7, 2013). "Audiophile label Opus3 starts offering 5.6448MHz DSD downloads". Pure Super Audio. Retrieved October 27, 2018.
  21. ^ "Digital HD Audio Formats". Archived from the original on June 21, 2015. Retrieved October 27, 2014.
  22. ^ "e20 Mk II - the first high-end DAC capable of DSD256".
  23. ^ "e20 Mk III - the first high-end DAC capable of 12.288 MHz (DSD256)".
  24. ^ "exaSound e20 Mk II".
  25. ^ "DSD512 ...upsampled free demo from www.wechdomi.org [Resolved with build 218]". April 17, 2017. Thanks @wizardofoz, managed to download the 'Wechseldominante - Babel DSD512\Wechseldominante - Babel (DSD512).dff' and playback on my Holo Spring DAC. Direct DSD512 playback is far less computer intensive if it doesn't do any form of conversion. I managed to playback DSD512 without any issue.
  26. ^ Robinson, David W. (April 2012). "The Higher End: From an Editor's Notebook - Downloadable DSD". Positive Feedback Online. Retrieved May 14, 2012.
  27. ^ MR-2000S
  28. ^ "PS3 SACD FAQ". PS3SACD.com. Archived from the original on October 19, 2018. Retrieved August 8, 2010.
  29. ^ "CES 2013 Announcement". January 8, 2013.
  30. ^ Koch, Andreas; et al. (March 30, 2012). "Method for transferring DSD Audio over PCM Frames Version 1.1". DSD-Guide.com. Archived from the original on May 15, 2012. Retrieved May 14, 2012.
  31. ^ Lipschitz, Stanley P.; Vanderkooy, John (September 22, 2000). "Why Professional 1-Bit Sigma-Delta Conversion is a Bad Idea" (PDF). Archived from the original (PDF) on November 2, 2022.
  32. ^ Lipshitz, Stanley P.; Vanderkooy, John (May 12, 2001). "Why 1-Bit Sigma-Delta Conversion is Unsuitable for High-Quality Applications" (PDF). Archived (PDF) from the original on April 30, 2023. Retrieved August 28, 2023.
  33. ^ Reefman, Derk; Janssen, Erwin (April 6, 2002). "Enhanced Sigma Delta Structures for Super Audio CD Applications". Audio Engineering Society. Retrieved October 23, 2024.
  34. ^ Angus-Whiteoak, Jamie A S. "The Effect of Idle Tone Structure on Effective Dither in Delta-Sigma Modulation Systems", "Session X: SIGNAL PROCESSING FORUM - PART 1". Audio Engineering Society 112th Convention, Munich, April, 2002, #5619. (Professor of Audio Technology) Professor James Angus BSc, PhD (Kent), FIOA, MAES Publications Research Projects
  35. ^ Vanderkooy, John; Lipshitz, Stanley P. (April 1, 2002). "Towards a Better Understanding of 1-Bit Sigma-Delta Modulators - Part 3". Audio Engineering Society. Retrieved January 23, 2021. "Session X: SIGNAL PROCESSING FORUM - PART 1". Audio Engineering Society 112th Convention, Munich, April, 2002..
  36. ^ Stuart, J. Robert (March 2004). "Coding for High-Resolution Audio Systems" (PDF). J. Audio Eng. Soc. 52 (3): 139–142. S2CID 18072620. Archived from the original (PDF) on February 7, 2021. Retrieved January 24, 2021.
  37. ^ Hawksford, M. (2001). "SDM versus LPCM: The Debate Continues" (PDF). AES Convention: 5397. Archived from the original (PDF) on May 13, 2006.
  38. ^ (Hawksford 1995).
  39. ^ See the AK5381 ADC datasheet
  40. ^ See the PCM4222 data sheet
  41. ^ Blech, Dominic; Yang, Min-Chi (2004). "DVD-Audio versus SACD: Perceptual Discrimination of Digital Audio Coding Formats" (PDF). Erich-Thienhaus-Institute (Tonmeisterinstitut). University of Music Detmold, Germany. Archived from the original (PDF) on September 27, 2007. Retrieved July 27, 2014.
  42. ^ Marui, A., Kamekawa, T., Endo, K. and Sato, E., 2014, April. Subjective evaluation of high resolution recordings in PCM and DSD audio formats. In Audio Engineering Society Convention 136. Audio Engineering Society.
  43. ^ Reiss, J.D., 2016. A meta-analysis of high resolution audio perceptual evaluation. Journal of the Audio Engineering Society, 64(6), pp.364-379.
  44. ^ Direct Stream Digital Interchange File Format (PDF), Royal Philips Electronics, 2004, retrieved July 15, 2022
  45. ^ a b c Media Types, IANA, 2022, retrieved July 15, 2022
  46. ^ a b c Freedesktop.org Shared MIME Database, Freedesktop.org, 2022, retrieved July 15, 2022
  47. ^ Specifications for 1-bit-coding Data File, version 1.0 (PDF) (in Japanese), 1-bit Audio Consortium, 2002, archived from the original (PDF) on October 11, 2003
  48. ^ Waseda University, Sharp, and Pioneer Establish 1-bit Audio Consortium to Promote Next-Generation Audio Technology, Pioneer, 2001
  49. ^ Specifications for 1-bit-coding Data File, version 1.1 (PDF) (in Japanese), 1-bit Audio Consortium, 2012, retrieved September 11, 2022
  50. ^ Robjohns, Hugh (March 2007), Korg MR1000 & MR1 — High-resolution DSD Master Recorders, Sound on Sound, retrieved October 16, 2022
  51. ^ French, Jez riley (December 21, 2010), KORG MR-2 recorder, retrieved October 16, 2022
  52. ^ Rudolph, Barry (January 8, 2009), Korg MR-2000S 1-Bit Studio Recorder Review, Mix, retrieved October 16, 2022
  53. ^ DSD Format License Agreement, Sony Corporation, 2006, archived from the original on April 17, 2006
  54. ^ DSF File Format Specification (PDF), Sony Corporation, 2005, retrieved July 15, 2022
  55. ^ Bryant, David (2020), WavPack 4 & 5 Binary File / Block Format (PDF), retrieved August 14, 2022
  56. ^ Compressing DSD files with Wavpack 5, DIY Audio Heaven, 2022, retrieved August 14, 2022
  57. ^ changelog.txt, wavpack.com, 2022, retrieved September 6, 2022
  58. ^ Koch, Andreas; McHarg, Andy; Rankin, Gordon; Jurewicz, Michal (2012), DoP Open Standard (PDF), retrieved July 15, 2022
  59. ^ Sonore dsd2flac, Simple Design, LLC, retrieved July 15, 2022
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