Everything you wanted to know about MQA

[novisnick]

Received an E-mail today that states that Media Players JRiver may support Tidal? MQA? Need to dig into this.
From my e-mail

”Tidal Support

Changes to our WDM driver have fixed a problem with playback of Tidal content. Just download and install MC23.0.81 or higher. You can route Tidal through JRiver so you can use JRiver's playback engine, control the volume with a remote, or apply DSP effects.”

[Loop 7]

Nov 16, 2017 23:36:45 GMT -5 novisnick said:

Received an E-mail today that states that Media Players JRiver may support Tidal? MQA? Need to dig into this.
From my e-mail

”Tidal Support

Changes to our WDM driver have fixed a problem with playback of Tidal content. Just download and install MC23.0.81 or higher. You can route Tidal through JRiver so you can use JRiver's playback engine, control the volume with a remote, or apply DSP effects.”

That's interesting but not surprised.

Amarra, Audirvana, Roon and now JRiver support TIDAL and MQA.

[Loop 7]

I'm still really curious if Spotify will decide to launch the rumored lossless service and, if so, if they will support MQA. I have my doubts on both.

[novisnick]

Oppo and MQA
MORE INFO HERE,

www.avsforum.com/mqa-audio-support-added-oppo-udp-205/?utm_source=email&utm_campaign=AVSForum.com_sold&utm_source=AVSForum.com20171128

[KeithL]

Other than dropping the name - I see a distinct LACK of details about what they're actually doing.
I'm guessing that they'll be doing a software decode (first unfold) on MQA files you play on the Oppo....... (rather than acting as a renderer).

Nov 28, 2017 15:19:03 GMT -5 novisnick said:

Oppo and MQA
MORE INFO HERE,

www.avsforum.com/mqa-audio-support-added-oppo-udp-205/?utm_source=email&utm_campaign=AVSForum.com_sold&utm_source=AVSForum.com20171128

[novisnick]

Nov 28, 2017 15:41:21 GMT -5 KeithL said:

Other than dropping the name - I see a distinct LACK of details about what they're actually doing.
I'm guessing that they'll be doing a software decode (first unfold) on MQA files you play on the Oppo....... (rather than acting as a renderer).

Nov 28, 2017 15:19:03 GMT -5 novisnick said:

Oppo and MQA
MORE INFO HERE,

www.avsforum.com/mqa-audio-support-added-oppo-udp-205/?utm_source=email&utm_campaign=AVSForum.com_sold&utm_source=AVSForum.com20171128

Thanks   @keithl   thats what I was thinking BUT, Apps dont unfold MQA, only the web based dervice to this point does that.
So, is this an app that unfolds or is the Oppo now a renderer/decoder? ie: full MQA rendering. Great question for Oppo and MQA developers.

Many unanswered questions but I still like the sound of most of their music

[Loop 7]

Nov 28, 2017 15:19:03 GMT -5 novisnick said:

Oppo and MQA
MORE INFO HERE,

www.avsforum.com/mqa-audio-support-added-oppo-udp-205/?utm_source=email&utm_campaign=AVSForum.com_sold&utm_source=AVSForum.com20171128

"...the company has added support for decoding MQA audio using the player’s built-in “Music” app."

Is the app to which they are referring handle the TIDAL streaming or is there a separate TIDAL app on each Oppo player?

[Casey Leedom]

Well, it looks like Stereophile is going to go wading deep into MQA in the current issue. Here's John Atkinson's editorial note:

"The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point."—Claude Shannon

Since its announcement at the end of 2014, Master Quality Authenticated, the MQA encoding/decoding system, has spawned outspoken criticism. Some of the more thoughtful negative reactions have come from engineers such as Dan Lavry, Bruno Putzeys, and Daniel Weiss. Others have been expressed by manufacturers of digital products: the late Charley Hansen at Ayre Acoustics, for example, along with Jason Stoddard and Mike Moffat at Schiit Audio, John Siau at Benchmark Media Systems, and Jim Collinson at Linn Products. Some have been audio writers: Doug Schneider, at SoundStage!, and Paul Miller and Jim Lesurf, at Hi-Fi News. Most vociferous have been anonymous website posters. As Jim Austin remarks in his examination of MQA's decoding of impulse-response data on p.127, "the nastiness online is unprecedented."

Typical of the nastiness are the following, taken from the Audio Asylum Web forum: "Nothing more entertaining than seeing Atkinson and Austin continuing to bury their reputation via MQA"; "MQA is a wholesale sellout"; and "If the very experienced editor of the numero uno in hifi mags (as JA is so fond of telling us) is in fact so easily duped, and even worse refuses to admit it and continues to praise what in [another poster's] view is a con, then I don't think he's worthy of much respect."

Am I being duped? I admit that, when I studied Stuart and Craven's 2014 AES paper introducing the concept (footnote 1), I found it theoretically elegant. (Peter Craven is an engineer whose ideas I have grown to respect over the years.) Subsequent demonstrations were convincing. In December 2014 I wrote, in an online news item, that "MQA will allow what appears to be true high-resolution audio to be delivered over the same Internet pipes over which music lovers currently experience at best CD-quality audio from Tidal or Qobuz."

The reduced data rate is due to the fact that, with files sampled at 2x, 4x, or 8x the baseband rate of 44.1 or 48kHz, the information in the first, second, and third ultrasonic octaves can be encoded and packed below the music's baseband noise floor in a 24-bit container. This "audio origami," as MQA calls it, results in a much smaller file than the hi-rez PCM equivalent, yet when the file is unfolded, the resolution and bandwidth of the original file are claimed to be preserved. I was initially skeptical of how the ultrasonic octaves could be separated from the baseband data without introducing artifacts, but studying the digital-signal-processing literature did seem to indicate that it was possible. And it is, of course, how digital-domain loudspeaker crossovers are implemented. In May 2016, I examined this claimed reduction in file size with some of my own 24-bit/88.2kHz recordings for which MQA's CEO, Bob Stuart, had sent me MQA equivalents. Not only were the MQA files smaller than the original PCM files, they were smaller than the uncompressed 16/44.1 CD version of the recording, so that claim by MQA is incontrovertible.

In that 2016 article I also examined the next claim made for MQA: that the encoded ultrasonic data can be encapsulated and buried in the least significant bits, beneath the original recording's analog noise floor. That claim, too, appeared to be correct, though there was a rise, undoubtedly inaudible, in the undecoded noise floor at close to half the sample rate that may well have be symptomatic of MQA's encapsulation of the ultrasonic data.

The most contentious claim made for MQA is that it can compensate for the time-domain errors of both the original A/D converters used to make a recording and the D/A converter used to play it back. This results in the complete recording/playback chain having an impulse response equivalent to a few feet of air, and temporal resolution of the same form and order as that of the temporal sensitivity of the ear-brain. Jim Austin examines the D/A aspect of this claim in his article in this issue, and other writers and I have conjectured that this time-domain compensation correlates with the always-superb sound quality we have heard from decoded MQA files.

However, optimizing the digital chain's behavior in the time domain involves using a very "short" antialiasing filter at the A/D conversion, and a similarly "short" reconstruction filter when the digital data are decoded. The more you constrain the data in the time domain, the less you can do so in the frequency domain. These filters are therefore "leaky," as you can see in the measurements accompanying the Aurender review in this issue, and will thus allow ultrasonic images to fold down into the baseband. Such filters are not new. Wadia's DigiMaster filter and Pioneer's Legato Linear filter both date back to the end of the 1980s, and the Listen filter in Ayre's D/A processors is also short and leaky, with a slow rolloff above the audioband. On the A/D side, converters from dCS and Ayre, both of which I use to make my own recordings, offer a switchable slow-rolloff antialiasing filter.

Does the filter's inherent aliasing degrade sound quality? That will depend on every recording's spectrum, and will be examined by Jim Austin in a future article, along with the question of whether MQA encodes ultrasonic information lossily or losslessly.

Other criticisms of MQA involve its implications for the recording industry, for manufacturers of audio products, and for consumers. I will examine those in next month's "As We See It."—John Atkinson

Casey

[rhale64]

Sounds interesting. Can't wait to read it.

[Casey Leedom]

The first of the promised articles has dropped: MQA Tested, Part 1.

Casey

[mgbpuff]

Wait, you mean this goes beyond opinion; it actually has real testing with graphic results? We can't have this in this measurement hating and MQA hater site! Even,someone like Moffat may have to take this Schiit seriously.

[Casey Leedom]

What I really found interesting in the Impusle Test that this first article covered was that the PCM file when fed through the Mytek Brooklyn DAC with MQA enabled showed exactly the same shape. This would seem to indicate that the actual data stream — MQA or PCM — wasn't really an issue here and that the Mytek Brooklyn DAC with MQA enabled is simply exhibiting a particular filter function. Which is interesting in it's own right.

Casey

[mgbpuff]

But an MQA file is formost a PCM file so why would you be surprised? It's what is folded inside and proprietorially recovered that makes an MQA decoded file different and the particular MQA proprietary digital filter and its extreme oversampling works on any PCM file. Thus the claim that it even improves on non MQA files.

[Casey Leedom]

That's fine, but that part of it is simply a "reconstruction filter". Maybe an interesting reconstruction filter, but a reconstruction filter none-the-less. For instance, the AK4490EQ showing up at some point in the upcoming RMC-1 offers five different reconstruction filters.

If there's any validity in MQA and their desire to own the entire encoding/decoding chain (with patents, licensing, DRM, etc.), it's only interesting if they truly can encode and correct for the error function on the original ADC.

Casey

[mgbpuff]

So you think MQA is just doing simple things and has nothing different to offer. They make a black box , but there's nothing in it except maybe someone else's black box. They are not valid (mathematically? or what?)and their desires to dominate a process they have expertise in (they are a capitalistic enterprise, you know) is not valid (that word again!). You know competitors can't be ruled out and if a market emerges for this type of product, competitors will appear. It's early, so just be dismissive until it can't be dismissed any longer!

[Casey Leedom]

Sorry, no, that wasn't what I was trying to say. I'll try again.

With respect to what was shown with the entirely digitally synthesized Impulse Function, in both MQA and PCM format, the Mytek Brooklyn DAC with MQA enabled showed exactly the same shape. Probably not too surprising since it was digitally synthesized I suppose. But what that shows is that that specific portion of the MQA DAC reconstruction can be considered as nothing more than a Reconstruction Filter. Quite possibly a very interesting Reconstruction Filter, but just that.

The only reason anyone would buy off on the MQA Format, which starts at the head of the ADC chain, is because of the promised ability to limit the over all Error Function from Original Sounds to Reproduced Sound.

As we've discussed a number of times, the ADC and DAC conversions both introduce errors. That is, we can look at it like this:

1. Original Sound --ADC--> Digital Data + ADC Error Function
2. Digital Data --DAC--> Reproduced Sound + DAC Error Function

In the above, the Digital Data is a digital approximation of the Original Analogue Sound. We then shove that Digital Approximation into the DAC which adds it's own errors to the process.

Imagine if we understood both the ADC and the DAC Error Functions Very Well and could encode the properties of the ADC Error Function in the Digital Data and use that in combination with known properties of the DAC Error Function to have an overall lower Error Function? I.e.:

1. Original Sound --ADC--> Digital Data + ADC Error Function
2. Digital Data + ADC Error Function Properties --DAC--> Reproduced Sound + ADC/DAC Error Function

Where hopefully the ADC/DAC Error Function << DAC Error Function, fed just the Digital Approximation.

Now, is the above what MQA does? No freaking clue. They've told a lot of different stories over the years. The one thing we have been told very reliably is that they want to own the entire chain, with licensing, etc. through the entire process. As such, it's something of an Intellectual and Artistic Land Grab.

Casey

[mgbpuff]

Everything down to your last sentence is exactly what MQA says they can do, and I'm not surprised they do not want to tell you exactly how they do that. That last sentence of yours however essentially reverts to your condemnation of a free market.

[Casey Leedom]

Yeah, I’m really not into closed ecosystems. So we’ll just have to agree to disagree on MQA’s overall value. It sounds like something you want and something I’m not willing to pay the price.

Casey

[novisnick]

Dec 12, 2017 21:12:50 GMT -5 Casey Leedom said:

Yeah, I’m really not into closed ecosystems. So we’ll just have to agree to disagree on MQA’s overall value. It sounds like something you want and something I’m not willing to pay the price.

Casey

I enjoy MQA streaming but Ive never purchased digital music besides a CD. Ive im going to own it Ill go with Vinyl. Ill rent to hear, at a reasonable price.

[mgbpuff]

My understanding is that MQA is NOT a closed system. A MQA file can be played by an ordinary DAC similar to HDCD was. Without a renderer and MQA DAC, you get the original file be it Redbook or higher rate.