Master Quality Authenticated

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MQA logo

Master Quality Authenticated (MQA) is a proprietary audio codec using lossy compression^[1] and a form of file fingerprinting, intended for high fidelity digital audio streaming media and music download.^[2] Launched in 2014 by Meridian Audio, it is now owned and licensed by MQA Ltd, which was founded by Bob Stuart, co-founder of Meridian Audio.

History[]

MQA was launched on 4 December 2014 at The Shard in London,^[3] although the concepts underpinning the development had previously been the subject of a presentation to the Audio Engineering Society British Section (10 June 2014)^[4] and a paper (published 8 October 2014) presented at the Audio Engineering Society 137th Convention in Los Angeles, CA in October 2014.^[5]

MQA was demonstrated to visitors to the Consumer Electronics Show in Las Vegas in January 2015.^[6] Several download/streaming services, playback system manufacturers and record labels have subsequently announced support for the technology. Early adopters included Pioneer Corporation, Onkyo, Meridian Audio, 7digital, Norwegian label Lindberg Lyd (2L), Mytek and others^[7]. Warner Music Group announced the signing of a "long-term licensing deal" with MQA at the Munich High End show in May 2016.^[8]

In May 2016, the Recording Industry Association of America (RIAA), in cooperation with the Recording Academy Producers & Engineers Wing, the American Association of Independent Music (A2IM), and DEG: The Digital Entertainment Group, announced that services providing music encoded in MQA are eligible to carry the industry's official logo mark for "Hi-Res MUSIC".^[9]

By 2017, popular record labels Warner Music, Universal Music and Sony Music along with independent labels’ body Merlin had partnered with MQA to make their music available in MQA audio.^[10]

In March 2018, MQA launched "Live", a virtual concert-going service designed to preserve the original sound quality of live performances.^[11] While playback will be available on any device, only devices compatible with MQA's proprietary codec may access the stream's "full quality."^[11]

In July 2019, Xiami Music adopted MQA technology though the music service was subsequently shuttered in February 2021.^[12]

In March 2020, MQA partnered with the British Music Embassy to present the British artists that were to appear at the cancelled SXSW 2020. The 30-minute sets were captured in MQA audio and HD video.^[13]

In April 2021, internet radio station Radio Paradise integrated MQA into all four of its mix channels on the BluOS platform.^[14]

Codec description[]

This section is missing information about how metadata such as the fingerprint and the source sample rate is stored in the LPCM output. Please expand the section to include this information. Further details may exist on the talk page. (November 2021)

MQA encoding is lossy;^[15] it hierarchically compresses the relatively little energy in the higher frequency bands into data streams that are embedded in the lower frequency bands using proprietary dithering techniques, allowing for an apparent reduction in sample rate and hence file size.

After a series of such "origami" manipulations, a dithered and shaped version of the original audio, together with a "touchup" stream (the compressed difference between the original and modified streams), are distributed as a single 24-bit stream, with the most significant bits occupied by PCM audio compatible with non-MQA playback equipment. Depending on the implementation, as few as 13 bits may be reserved for PCM audio, with the lower-order bits rendered as noise by equipment without an MQA decoder.^[16]

One more difference to standard formats is the sampling process. The audio stream is sampled and convolved with a triangle function, and interpolated later during playback. The techniques employed, including the sampling of signals with a finite rate of innovation, were developed by a number of researchers over the preceding decade, including Pier Luigi Dragotti and others.^[17][18]

MQA-encoded content can be carried via any lossless file format such as FLAC or ALAC; hence, it can be played back on systems either with or without an MQA decoder. In the latter case, the resulting audio has easily identifiable high-frequency noise occupying 3 LSB bits, thus limiting playback on non-MQA devices effectively to 13 bit. MQA claims that nevertheless, the quality is higher than "normal" 48/16, because of the novel sampling and convolution processes.^[19]

Other than the sampling and convolution methods, which were not explained by MQA in detail, the encoding process is similar to that used in XRCD and HDCD.

However, unlike other lossy compression formats like MP3 and WMA, the lossy encoding method of MQA is similar to aptX, LDAC and WavPack Hybrid Lossy, which uses time-domain ADPCM and bitrate reduction instead of perceptual encoding based on psychoacoustic models.

Reception[]

Praise[]

While the technology has received little comment in the general and mainstream press, its release was covered by the audiophile and hi-fi press. Positive reception included The Absolute Sound and Stereophile. Robert Harley, editor of The Absolute Sound has referred to it as "The most significant audio technology of my lifetime".^[20] Editor John Atkinson writing in Stereophile magazine following the UK launch in December 2014 wrote "In almost 40 years of attending audio press events, only rarely have I come away feeling that I was present at the birth of a new world."^[21]

Criticism[]

MQA has received criticism from various sources within the music industry.

An article titled Digital Done Wrong^[22] on the International Audio/Video Review web site, concluded that MQA is founded on a fundamentally unsound understanding of correct digital audio processing and found that playback of a sample MQA encoding demonstrated gross distortion and reconstruction failure. It did however comment that some listeners may find the technical defects of MQA encoding subjectively pleasing.

Artist Neil Young has expressed dislike for the MQA format, saying the masters are "degraded and manipulated" when encoded to MQA and has consequently removed his music from Tidal after finding out that his catalog on the service was encoded in MQA without his permission, criticizing Warner Music Group (who owns the label that Young has released most of his catalog through (Reprise Records)) for encoding music whose masters are no better than CD-quality in MQA. He also characterizes the format as a way to collect royalties.^[23]

Some critical comments have been made in online forums such as the Audiophile Style forum^[24] and in audio magazine website comments, and a few writers have expressed concern in some areas. Over 80 detailed questions, some of which voiced these concerns, were submitted to the editors of the Audiophile Style forum and subsequently addressed in detail by the creator of MQA, Bob Stuart, in an extended question-and-answer article.^[25] The editors of Audiophile Style forum subsequently updated the article with a disclaimer that "Most of Bob Stuart's answers have been debunked and the MQA technology is now seen as lacking any benefit for anyone other than record labels and MQA Ltd."^[25]

Audio product manufacturer Schiit Audio announced that it will not be supporting MQA due to, amongst other reasons, the understanding that "…supporting MQA means handing over the entire recording industry to an external standards organization."^[26]

In a blog post title "MQA is Bad for Music. Here's why"^[27] Hi-fi Manufacturer Linn Products criticises MQA's licensing requirements, asserting that MQA is "...an attempt to control and extract revenue from every part of the supply chain, and not just over content that they hold the rights for."^[27] After having discussed several disadvantages for both the artist and the consumer Linn concludes that as a consumer you will "…pay a higher price for the same music, and you'll pay more for your hi-fi system too. And even if you don't buy into MQA, everyone will get less innovation, creativity and poorer music as a result."^[27]

In an interview for online publication Positive Feedback, engineer Andreas Koch is critical of MQA due to its lossy algorithms and compression, along with its licensing requirements; also saying that a format such as this "does not solve any problem that the world currently has."^[28] Koch was involved in the creation of the Super Audio CD, the development of the Direct Stream Digital codec, and is co-founder of audio product manufacturer Playback Designs.

A YouTube video examining MQA through the use of author-created audio tracks released on Tidal was posted by GoldenSound, an audio equipment reviewer.^[29] Through analysis of tracks before and after MQA conversion, the author says that encoding a file in MQA alters the sound encapsulated in the file to its detriment. The YouTuber deduced that this method of encoding shows MQA has been providing unfounded information on how their encoding and format work. In response, MQA deleted the files quickly and stated that the files supplied were not dithered but truncated 16-bit files (meaning they were of higher bit rate originally) leading to the issues in encoding.^[30] GoldenSound disputes this, saying they have tested the track both dithered and undithered. GoldenSound also reports ineffectiveness of the fingerprinting technique.^[29][31][32]

Hardware and software decoders[]

Hardware decoders are manufactured by Pioneer, iFi Audio, Onkyo, Mytek, Meridian, Cocktailaudio and Bluesound. Selected Meridian products will support MQA thanks to a firmware update. On software side, the desktop application by Tidal supports MQA.^[33]

Commercial MQA-capable playback devices require payment of a royalty to MQA Ltd per unit sold. Based on information from Auralic, a manufacturer of Audiophile Wireless Audio Streamers, Meridian Audio prohibits digital output of unpacked MQA in any digital format, only allowing the unpacked data to be fed to an on-board MQA-compatible DAC and output in analog form. Some say this to be a kind of DRM process,^[19] which allows a proper MQA file to be authenticated and the full quality of the signal decoded only on commercially licensed equipment.

The USB Audio Player Pro software for Android has a one-off, in-app purchase by the customer to activate the MQA decoder.^[34]

The Roon software illustrates an alternative pay-by-use charging model. It supports decoding and handling MQA files and streams end to end.^[35] Comments from the COO suggest a pay-by-use charging model.^[36]

MQA-CD[]

CDs encoded with MQA were released exclusively in Japan in 2017 with label Ottava being the first to release a MQA-CD followed by other labels like Universal Music Japan soon after.^[37] An MQA-CD can be played with any CD player as long as a MQA decoder is connected. If not then the regular PCM audio will play instead of the higher quality sound.^[38][39][40]

Streaming services[]

Starting in January 2017, Tidal provides MQA audio to subscribers of the Tidal "HiFi" package.^[41] Tidal Masters songs are streamed at 96 kHz/24 bit.^[42][43] The application of the MQA technology has helped live streaming of 2020’s SXSW festival,^[44] and in British Underground’s livestream series, The Master Sessions.^[45]

References[]

Further reading[]

• Treatise on technical aspects of MQA