Master Quality Authenticated (MQA) is a lossy audio compression format, which is used to transfer high quality audio to a smart phone or audio device.[1] The tech was launched in 2014 by Meridian Audio, and is now owned and licensed by MQA Ltd.[2] MQA is a proprietary system and requires licensing fees to use.
The press launch of MQA was held in December 2014 in London,[3] followed by the company hosting a demonstration room at the Consumer Electronics Show in Las Vegas in January 2015.[4] The initial hardware manufacturers which offered MQA decoding were Pioneer, Onkyo, and Mytek.[5] In May 2016, Warner Music Group signed a long-term licensing deal with MQA.[6][7]
The RIAA announced in May 2016 that MPEG-4 SLS and MQA were eligible to use the Hi-Res MUSIC logo on their products;[8] the latter despite the logo being intended for lossless audio recordings.[9] By 2017, music distribution companies Warner Music Group, Universal Music Group, Sony Music and Merlin Network had agreed to make some of their recordings in MQA format.[10] Xiami Music began offering MQA streaming via its SVIP pricing tier in July 2019, however the music service was discontinued in February 2021.[11]
In March 2018, an MQA Live encoder box was released, which is intended for live music concerts to be streamed using the MQA compression algorithm.[12]
In April 2021, internet radio station Radio Paradise began offering MQA on its channels.[13]
In May 2021, the Apple Music streaming service announced a Lossless Audio pricing tier, which was described as a "death knell" for MQA.[14]
MQA encoding is lossy;[15][16] 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,[17][18] 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.[19]
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.[20][21]
MQA-encoded audio can be contained with file formats such as FLAC, ALAC or CD-DA; hence, it can be played back on systems either with or without an MQA decoder. In the latter case, the resulting audio contains high-frequency noise occupying the three least-significant bits, thus limiting playback on non-MQA devices effectively to 13 bit. Despite this, MQA claims that the quality is higher than "normal" 48/16, because of the novel sampling and convolution processes.[22]
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.
Robert Harley, editor of The Absolute Sound stated in March 2016 that MQA "will forever change the way we and future generations consider digital audio".[23]
John Atkinson, editor of Stereophile stated the following about the launch of MQA in December 2014 "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."[24]
In the 2L Records 2015 announcement of an MQA remastered release of piano recordings, company owner Morten Lindberg stated "I have spent many hours with Bob listening to original recordings and being constantly amazed by the incredible sense of space and clarity brought by MQA", in comparison to the drawbacks and weaknesses of the early digital technology originally used for the recordings.[25]
In the Atlantic Records announcement that it would sell records using the MQA format, CEO Craig Kallman stated in May 2016 that "MQA makes high-resolution music easy to stream or download to any device. Music fans will love it when they hear it, and WMG is thrilled to be partnering with MQA to take the next step in bringing hi-res music to consumers around the globe".[26] Similarly, when Universal Music Group announced in February 2017 that they would be selling songs in MQA format, company executive Michael Nash stated "with MQA, we are working with a partner whose technology is among the best solutions for streaming high-res audio, and one that doesn’t ask music fans to compromise on sound quality for convenience".[27]
An article titled "Digital Done Wrong"[28] 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.
Singer and musician 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.[29]
Some critical comments have been made in online forums such as the Audiophile Style forum[30] 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.[31] 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."[31]
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."[32]
In a blog post title "MQA is Bad for Music. Here's Why,"[33] 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."[33] 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."[33]
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."[34] 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.
The GoldenSound audio equipment review website examined MQA through the use of author-created audio tracks released on Tidal.[35] Through analysis of tracks before and after MQA conversion, it was found that encoding a file in MQA alters the sound encapsulated in the file to its detriment.[36] GoldenSound deduced that this method of encoding shows MQA has been providing unfounded information on how their encoding and format work. Shortly after contacting MQA for clarification about the issues, the files in question were deleted from Tidal. MQA 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.[37] GoldenSound disputes this, saying they have tested the track both dithered and undithered. GoldenSound also reports ineffectiveness of the fingerprinting technique,[35][38][39] which was also experienced by Neil Young and FredericV.[40]
Hardware decoders are sold by Pioneer, iFi Audio, Onkyo, Mytek, Meridian Audio, Cocktailaudio and Bluesound. Software decoders are sold by Tidal (in the "HiFi" and "Masters" pricing tiers),[41][42][43][44] USB Audio Player Pro[45] and Roon (the latter based on a pay-by-use pricing model, with the company indicating that they are charged by MQA Ltd every time a song is core decoded).[46][47]
Compact disks encoded with MQA (MQA-CD) were first released in 2017, beginning with the publisher Ottava.[48] The MQA decoding will occur if an MQA decoder is connected.[49][50][51]
Commercial MQA-capable playback devices require payment of a royalty to MQA Ltd per unit sold. MQA Ltd 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. Dr Christoph Engemann of Leuphana University Lüneburg described MQA as a "stealth DRM trojan".[22] Live recording specialists nugs.net integrated MQA support for downloads in 2017 and expanded playback to iOS streaming in early 2018.[52]
