High-resolution audio, also known as High-definition audio or HD audio, is a marketing term used by some recorded-music retailers and high-fidelity sound reproduction equipment vendors. It refers to higher than 44.1 kHz sample rate and/or higher than 16-bit linear bit depth. It usually means 96 kHz (or even much higher), sometimes informally written as "96k", meaning a Nyquist frequency of 48 kHz. However, there also exist 44.1 kHz 24 bit recordings that are labeled HD Audio .
High-resolution audio is generally used to refer to music files that have a higher sampling frequency and/or bit depth than that of Compact Disc Digital Audio, which is specified at 16bit/44.1 kHz.
The Recording Industry Association of America (RIAA), in cooperation with the Consumer Electronics Association, DEG: The Digital Entertainment Group, and The Recording Academy Producers & Engineers Wing, formulated the following definition of high-resolution audio in 2014: "lossless audio capable of reproducing the full spectrum of sound from recordings which have been mastered from better than CD quality (48kHz/20-bit or higher) music sources which represent what the artists, producers and engineers originally intended.
This includes pulse-code modulation (PCM) encoded audio with sampling rates greater than 44,100 Hz and with bit-depths greater than 16, or their equivalents using other encoding techniques such as pulse-density modulation (PDM).
One of the first attempts to market high-resolution audio was High Definition Compatible Digital in 1995. This was followed by three more optical disc formats claiming sonic superiority over CD-DA: DAD in 1998, SACD in 1999, and DVD-Audio in 2000. None of these achieved widespread adoption.
Further attempts to market high-resolution audio on optical disc followed with Pure Audio Blu-ray in 2009, and High Fidelity Pure Audio in 2013. Competition in online high-resolution audio retail stepped-up in 2014 with the announcement of Neil Young's Pono service.
Consumer audio products that came with the "Hi-Res AUDIO" logo indicate that the product meet the specification required for a high resolution audio product, as defined by Japan Electronics and Information Technology Industries Association (JEITA).
Most recently, Sony has reaffirmed its commitment towards the development of high resolution audio segment by offering a slew of Hi-Res Audio products as it seeks to re-establish its leadership in consumer audio products.
Whether there is any benefit to high-resolution audio over CD-DA is controversial, with some sources claiming sonic superiority:
- "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.—The Mariinsky record label of the Mariinsky Ballet (formerly Kirov Ballet), St. Petersburg, Russia, that sells Super Audio CDs (SACDs)
- "the main claimed benefit of high-resolution audio files is superior sound quality [..] 24-bit/96k or 24-bit/192kHz files should therefore more closely replicate the sound quality that the musicians and engineers were working with in the studio. [..] As always, though, there are some people who can't hear a difference. So, if you can't see or hear a difference, save your money…"—What Hi-Fi?
and with other opinions ranging from skeptical to highly critical:
- "If they [the music business] cared about sound quality in the first place, they would make all of the releases sound great in every format they sell: MP3, FLAC, CD, iTunes, or LP."—cnet
- "Impractical overkill that nobody can afford"—Gizmodo
- "A solution to a problem that doesn't exist, a business model based on willful ignorance and scamming people."—Xiph.org
Business magazine Bloomberg Businessweek suggests that caution is in order with regard to high-resolution audio: "There is reason to be wary, given consumer electronics companies’ history of pushing advancements whose main virtue is to require everyone to buy new gadgets."
High resolution files that are downloaded from niche websites that cater to "audiophile" listeners often include different mastering in the release – thus many comparisons of CD to "special" releases are evaluating differences in mastering, rather than bit depth.
Most early papers using blind listening tests concluded that differences are not audible by the sample of listeners taking the test. Blind tests have shown that musicians and composers are unable to distinguish higher resolutions from 16-bits 48 kHz One 2014 paper showed that dithering using outdated methods (rectangular unshaped dither, rather than the industry standard triangular dither) produces audible artifacts in blind listening tests.
- Shankland, Stephen. "Sound bite: Despite Pono's promise, experts pan HD audioSound bite: Despite Pono's promise, experts pan HD audio". c|net. CBS Interactive Inc. Retrieved 22 March 2014.
the "HD audio" movement also called high-resolution or high-definition audio
- Aguilar, Mario (June 2013). "What Is High-Resolution Audio?". Gizmodo. Gawker Media. Retrieved 17 March 2014.
High-resolution audio is a new industry marketing term
- "High Resolution Audio Initiative Gets Major Boost with New "Hi-Res MUSIC" Logo and Branding Materials for Digital Retailers". The Recording Industry Association of America(RIAA). Retrieved 21 August 2018.
- "High-resolution audio: everything you need to know". What Hi-Fi?. Haymarket Publishing. 10 June 2015. Retrieved 11 October 2016.
there's no universal standard for high-res audio
- "Home Technology eMagazine - Classic Home Toys Installment #19 The Final CD Format: HDCD". HomeToys. Archived from the original on 2014-03-18. Retrieved 2012-08-05.
HDCD is capable of higher quality sound reproduction because HDCD encodes the equivalent of 20 bits worth of data
- "Definition of:high-resolution audio". PCMag. Ziff Davis. Retrieved 18 March 2014.
HDtracks (http://www.hdtracks.com) pioneered high-resolution audio via download
- "Universal Music bets on consumer longing for quality with hi-fi Pure Audio". DVD & Beyond. Globalcom Limited. Retrieved 4 January 2014.
- O'Malley Greenburg, Zack. "How Neil Young's Pono Music Raised $2 Million in Two Days". Forbes. Forbes.com LLC. Retrieved 15 March 2014.
He’ll have some competition. Already, services like HDtracks.com have seen triple-digit growth in downloads of top-notch digital files
- "What are the benefits of SACD?". Mariinsky Label FAQ (Press release). Archived from the original on January 1, 2014. Retrieved January 1, 2014.
this album is available to buy on SACDCS1 maint: BOT: original-url status unknown (link)
- Guttenberg, Steve. "What's up with Neil Young's Pono high-resolution music system?". c|net. CBS Interactive Inc. Retrieved 18 March 2014.
- "What is High-Resolution Audio?". AudioReputation. Retrieved 21 July 2018.
- Brustein, Joshua. "Music Snobs, Neil Young Has a Product for You". BLOOMBERG BUSINESSWEEK. BLOOMBERG L.P. Retrieved 17 March 2014.
- "Audibility of a CD-Standard A/D/A Loop Inserted into High-Resolution Audio Playback" (PDF). J. Audio Eng. Soc. Retrieved 24 March 2015.
- On a testé... la musique en haute définition.
- "The Audibility of Typical Digital Audio Filters in a High-Fidelity Playback System". J. Audio Eng. Soc. Retrieved 9 November 2015.