Master Quality Authenticated
Master Quality Authenticated is an audio codec using lossy compression and a form of file fingerprinting, intended for high fidelity digital audio internet streaming and file download. 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, although the concepts underpinning the development had previously been the subject of a presentation to the Audio Engineering Society British Section and a paper presented at the Audio Engineering Society 137th Convention in Los Angeles, CA in October 2014.MQA was demonstrated to visitors to the Consumer Electronics Show in Las Vegas in January 2015. Several download/streaming services, playback system manufacturers and record labels have subsequently announced support for the technology, including Pioneer Corporation, Onkyo, Meridian Audio, 7digital, Norwegian label Lindberg Lyd, Mytek and others, with Warner Music Group announcing the signing of a "long-term licensing deal" with MQA at the Munich High End show in May 2016.
In May 2016, the Recording Industry Association of America, in cooperation with the Recording Academy Producers & Engineers Wing, the American Association of Independent Music, 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".
In March 2018, MQA launched "Live", a virtual concert-going service designed to preserve the original sound quality of live performances. While playback will be available on any device, only devices compatible with MQA's proprietary codec may access the stream's "full quality."
Codec description
MQA encoding is lossy; 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 but after the decoding the result would be the lossless archive.After a series of such manipulations, the resulting 44.1 kHz data, the layered data streams, and a final "touchup" stream are provided to the playback device.
Given the low amount of energy expected in higher frequencies, and using only one extra frequency band layer and one touchup stream are together distributed as a 48/24 stream, of which 48/16 bit-decimated part can be played by normal 48/16 playback equipment.
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.
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.
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
While the technology has received little comment in the general and mainstream press, it has been exalted by the audiophile and hi-fi press. Robert Harley, editor of The Absolute Sound has referred to it as "The most significant audio technology of my lifetime". 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."Criticism
MQA has received criticism from various sources within the music industry.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."
In a blog post title "MQA is Bad for Music. Here's why" 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." 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."
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." 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.
An article titled Digital Done Wrong 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.
Some critical comments have been made in online forums such as the Audiophile Style forum 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.
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.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 claim this to be a kind of DRM process, which allows a proper MQA file to be authenticated and the full quality of the signal decoded only on commercially licensed equipment.