MQA is Vaporware

[John_Atkinson]

18 hours ago, Archimago said:

IMO both Atkinson and Harley selected doozies about "birth of a new world" and "paradigm shifts" when they "picked" to misrepresent and hype up mQa the way they did.

 

The context for my "birth of a new world" comment - I haven't written "paradigm shift" - was this, written 7 years ago: "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. In March 1979, I visited the Philips Research Center in Eindhoven, Holland and heard a prototype of what was to be later called the Compact Disc. In the summer of 1982, I visited Ron Genereux and Bob Berkovitz at Acoustic Research's lab near Boston and heard a very early example of the application of DSP to the correction of room acoustic problems. And in early December, at Meridian's New York offices, I heard Bob Stuart describe the UK company's MQA technology, followed by a demonstration that blew my socks off."

 

See https://www.stereophile.com/content/ive-heard-future-streaming-meridians-mqa, where I concluded that "Judging by the recordings I heard in Manhattan, some dating back to the early 1950s, I feel the launch of Meridian's MQA is as important to the quality of sound recording and playback as digital was 40 years ago."

 

I thought it obvious that my comments were based on the sound quality of the demonstrations I experienced, and my views haven't changed as result of the further comparisons that I have performed. I recently arranged a blind comparison of one of my own recordings in original 24/88.2k form and the MQA-encoded version for a visiting engineer. His preference for the MQA version was the same as I had originally reported in 2016: that there was less ambiguity in the spatial relationships between the performers and the surrounding acoustic with the MQA version (See https://www.stereophile.com/content/listening-mqa.)

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

1 hour ago, firedog said:

Wow, one listening test of one recording by one engineer. Definitive proof....not

 

With respect, you are disregarding all the other listening tests and comparisons in which I have taken part. Yes, those were almost all sighted - you can find them all on the Stereophile website. However, given that Audiophile Style, like Stereophile, publishes reviews based on sighted listening, are you really saying that sighted listening doesn't produce reliable results?

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

1 minute ago, botrytis said:

Directed listening, no double blind. Sorry, but your assertion means squat.

 

In that case, doesn't that mean that all sighted listening is "squat."

1 minute ago, botrytis said:

I have done a blind listening at a dealer and I can say mQa sounds worse. Period.

 

And I wrote earlier in this thread that I organized a blind test of MQA that gave the opposite result, only to have other posters on this forum say that a single test doesn't mean anything. I assume they will point that out to you also.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

2 hours ago, MikeyFresh said:

What about the various ADC chip makers and gear manufacturers, haven't they demanded to be in on this incredible new world/paradigm too?

 

I know you are "cracking wise" but dCS has always offered a very short antialiaslng fliter on its A/D converters to reduce the otherwise inevitable sinc-function ringing on transients. And the late Charley Hansen of Ayre was also concerned about optimizing time-domain behavior. He used a "moving averages" filter for the Ayre QA-9 A/D converter that I found produced a perfect impulse response, at the expense of allowing some low-level aliasing energy. At a sample rate of 192kHz this was inconsequential.

 

Before Charley passed he sent me an experimental complementary reconstruction filter for the Ayre D/A converters. This allowed perfect time-domain behavior throughout the recording-reproduction chain, just as is claimed for MQA. That was ironic indeed, given Charley's hatred of MQA. For reasons unknown Ayre never released this reconstruction filter.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

12 hours ago, mfsoa said:

14 hours ago, John_Atkinson said:

This allowed perfect time-domain behavior throughout the recording-reproduction chain, just as is claimed for MQA

Did MQA achieve this, or are they lying? No one is a better position to tell us than you.  Why won't you tell us?

I wanted to borrow an A/D converter fitted with the MQA encoder in order to examine its behavior in the time domain, as I had done for Charley Hansen's transient-perfect antialiasing filter. However, in order to be able to do so I would have been required to sign an NDA, which would have defeated the purpose.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

4 hours ago, Archimago said:

I notice that @John_Atkinson is very shy about answering questions about the "birth of a new world".

 

Not shy. Everything I have had to say on MQA since 2014 is available on Stereophile's website, at www.stereophile.com/category/mqa . I also examined the band-splitting and buried data channel aspects of MQA in a series of posts on Audio Science Review earlier this year. See, for example, https://www.audio “science” review/forum/index.php?threads/mqa-deep-dive-i-published-music-on-tidal-to-test-mqa.22549/page-72#post-760938

https://www.audio “science” review/forum/index.php?threads/mqa-deep-dive-i-published-music-on-tidal-to-test-mqa.22549/page-72#post-760969

and https://www.audio “science” review/forum/index.php?threads/mqa-deep-dive-i-published-music-on-tidal-to-test-mqa.22549/page-79#post-762223

 

Other than the reduced need to keep streamed file sizes small, I haven't seen or read anything on this site or others that leads me to change my mind about the format's technical elegance.

 

On the commercial aspects of MQA, which are monopolistic, I commissioned and published an article on this in early 2018: https://www.stereophile.com/content/mqa-benefits-and-costs

 

To quote from that article: "Once securely in place in the industry, MQA would be very difficult to dislodge, and its very dominance would deter the development of newer, possibly better formats—or even discourage the retaining of such current alternatives as WAV, FLAC, etc., as viable choices in the marketplace."

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

On 8/28/2021 at 7:58 PM, lucretius said:

 

Which one of MQA Ltd's claims has stood up to scrutiny, that would cause you to continue believing in the format's technical elegance?

 

I still think how MQA works is indeed elegant. It recognizes that with real-world music, the spectral energy falls off with increasing frequency and that the recording's analog noisefloor is higher than the 24-bit floor. (With my choral recordings, which have very low acoustic and electronic noise - see attached room tone spectrum -  the noisefloor can be accurately encoded with an 18-bit word length.) The former means that the energy above 1Fs can be quantized with a small number of bits and the latter means that those ultrasonic data can be encrypted to resemble pseudo-random noise and buried in a hidden data channel in bits 19-24 beneath the analog noisefloor. There is a slight noise penalty but it is a fraction of a dB. And as noise is noise, you can't detect the buried data channel by ear.

 

This buried data technique is called steganography and is widely used in telecommunications and video technology - however, because the bottom bits now contain information, the data's entropy is higher and FLAC can't compress an MQA-encoded file as much as it can a straight 24-bit audio file.

 

As Jon Iverson wrote in the article I referred to in my earlier posting, MQA offers benefits to both the record industry and the consumer. The former is no longer allowing free access to its unencrypted masters; the latter gets an improvement in sound quality. (The saving in bandwidth is no longer relevant, except for people who don't have unlimited data plans and want to stream hi-rez audio to their phones.) The benefit to the consumer is the "deblurring" that I discussed in a 2018 article: www.stereophile.com/content/zen-art-ad-conversion. The post-Shannon sampling - see https://ieeexplore.ieee.org/document/843002 - allows the ADC/DAC chain to be optimized to preserve transient information. Again, this is not new; Post-Shannon sampling is used in video when you don't want image edges to be burred, as in cartoons and anime.

 

The price to be paid for the deblurring is the introduction of a small amount of aliased image energy. When you consider the spectral distribution of real-word music, this aliased energy will lie below the recording's original noisefloor and is therefore inconsequential.

 

Unlike Apple/Dolby Atmos, MQA has not done a good job of selling the benefit to the consumer, which is why everyone complains about losing open access. (Audio has been the only medium where there haven't been proprietary closed formats - no-one complains about Dolby Digital, DTS, Dolby Atmos, DVD, Blu-ray etc, etc, where there are large license fees involved for manufacturers wanting to offer those formats.)

 

John Atkinson

Technical Editor, Stereophile
 

[John_Atkinson]

1 hour ago, garrardguy60 said:

Jim Austin is now appealing to non-sentient intelligence to help p*mp MQA.

 

His latest "As We See It" is entitled "A Chatbot's Take on Hi-Fi Issues." He also takes the opportunity to bash everyone who's not on the MQA thin-gravy train. Here is an excerpt from the end of the column. (I haven't posted the link because I'm not sure what Chris's policies are re outside links.)

 

Here's the close of the column:

 

[JA2]: Wait, MQA uses time-smearing to compensate for time-smearing?

 

ChatGPT: Yes, that's correct! MQA technology uses a technique called "time-smearing" to compensate for the effects of time-smearing on transients in the music.

 

 

With respect, you're missing the point. Jim trapped ChatGPT into a tautological loop: "MQA technology uses a technique called 'time-smearing' to compensate for the effects of time-smearing. ... time smearing compensates for time smearing ...time smearing compensates for time smearing ..." This has nothing to do with MQA per se. See the full essay at https://www.stereophile.com/content/chatbots-take-hi-fi-issues

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

59 minutes ago, Currawong said:

I posted this in reply to the Stereophile article. Either something glitched on my end, or it has been moderated in some way, as I can't see it. 

It is definitely posted this morning.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

5 hours ago, firedog said:

It's amazing at this point that JA1 still feels compelled to defend calling MQA lossless.

I didn't say "lossless." With all due respect, I think you didn't comprehend what I wrote: "While it is true that the bits in an MQA-encoded file are not the same as those in the original hi-rez file, this does not necessarily mean that the format is 'lossy' in the manner that MP3, AAC, etc are lossy."

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

5 hours ago, firedog said:

Yes, I understood what you wrote. But the context was you responding to someone that called it lossy. So essentially you were trying to shoehorn it into being lossless, as it were, by responding to that. 

Simply put - it's necessarily lossy by the accepted definition of the terms "lossy" and "lossless". 

 

Yes, less lossy, but can't truthfully be called lossless. 

 

And as I wrote,  regardless of your statements I didn't say MQA was lossless.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

24 minutes ago, jhwalker said:

You said it's "not lossy".  

 

I am beginning to think that some people lack comprehension skills. I did not say MQA is "not lossy." What I wrote was that "While it is true that the bits in an MQA-encoded file are not the same as those in the original hi-rez file, this does not necessarily mean that the format is 'lossy' in the manner that MP3, AAC, etc are lossy." You omitted the final 9 words in that sentence, thus misrepresenting my statement.

 

If you look at the measurements I have performed on lossy codecs like MP3 and AAC - see https://www.stereophile.com/features/308mp3cd/index.html - and APT-X and A2DP - see https://www.stereophile.com/content/chord-chordette-gem-da-processor-measurements - you can see that these codecs discard real music information and compromise the analog noisefloor in order to reduce the bitrate. MQA behaves differently from those codecs, and while the unfolded/upsampled bits are not identical to those in the original hi-rez PCM file, in theory no music information is lost and the analog noisefloor is that of the original recording.

 

All I am saying that MQA is different in principle to codecs like MP3 etc. You are welcome, of course, to regard it as "lossy"

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

3 hours ago, Currawong said:

Time smearing correction is not physically possible.

 

Incorrect. My 2018 article on A/D conversion - https://www.stereophile.com/content/zen-art-ad-conversion -  gave an example of how this was achieved using an A/D converter with a slow-rolloff antialiasing filter (a dCS 904's F4 filter) and a D/A converter with a slow-rolloff reconstruction filter (an Ayre QB9's Listen filter).

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

1 hour ago, jhwalker said:

It's not MY "comprehension skills" lacking  🙄

 

I was responding to the incorrect assertions made on this forum that I wrote that MQA was "lossless." I didn't and wouldn't.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

1 hour ago, RichardSF said:

Something that struck me is that when MQA Ltd went into receivership in April, Stereophile and TAS went silent on the topic for months. No commentary about it, or even reporting it as audio news.

 

Not on the magazine's website, no. But it was covered in the print magazine.

 

John Atkinson

Technical Editor, Stereophile

[John_Atkinson]

14 hours ago, Currawong said:

This is the issue I have with John Atkinson's article where the ringing of impulse responses is equated with musical transients. An impulse response is an illegal signal -- it's a single positive sample, which by being completely out of bandwidth, causes a digital filter to reveal itself as it attempts to process what amounts to all frequencies at once. 

 

Note that in my article, I used, not a single sample at 0dBFS to test A/D converters, but a PCM test signal sampled at 384kHz with a white spectrum and a 60kHz bandwidth -see figs.4 and 5 at https://www.stereophile.com/content/zen-art-ad-conversion - that I converted to analog.

 

I do use a single sample at 0dBFS for my tests of D/A processors, as this maps the reconstruction filter's coefficients.

 

John Atkinson

Technical Editor, Stereophile