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MQA Deep Dive - I published music on tidal to test MQA

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awdeeoh

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MQA has an upgrade path though.
MQA 2.0 will lose 2 bits at twice the licensing cost.
MQA 3.0 will lose 1 bit at four times the licensing cost.

Then we'll get SuperMQA, which will lose zero bit at 8 times the licensing cost. At that point, there will be critics who will say it is awfully similar to some olds standards. People won't know, because the device will still be a black box. Critics will be dismissed as shills paid by the competition.

It is worth noting, now that we are 66 pages into this thread, that while we have seen attacks on the criticism, dismissal of critics and, ad-hominems, we haven't seen a single message about a benefit of MQA for customers.

The benefit of the blue light. It gives them a sense of comfort - this is the master, sounds so good and sweet like a candy.
 

John Atkinson

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Here is your measurement from MQA Tested Part2:
MQA Tested Part 2- Into the Fold_DXDMQADiagram.jpg

This was actually in an article written by Stereophile editor Jim Austin, An updated measurement can be found at https://www.stereophile.com/content/mqa-aliasing-b-splines-centers-gravity-improved-mqa-encoding

John Atkinson
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John Atkinson

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For clarity on the issue of IEEE membership (I'm a full member, as I know are a number of others posting here), to quote from the IEEE website: "Associate member grade is designed for technical and non-technical individuals who do not meet the qualifications for member grade but who wish to benefit from membership and partnership in IEEE, and for those who are progressing, through continuing education and work experience, toward qualifications for member grade." (https://www.ieee.org/membership/qualifications.html)

Associate member of the IEEE but to avoid any confusion on this issue, I am a full member of the AES, not an associate member.

And as I wrote, I am not "arguing by credential." I was responding to a poster's misleading implication that I don't have any audio engineering credentials.

John Atkinson
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I don't think it is an accident that the two members of the Stereophile staff that I actually respect are the ones posting here. And I am sympathetic to the position that their employment puts them in. We should not have high expectations of the audiophile press, any more so than the car magazine guys. Both function as little more than external PR departments for the industry interests. We can wish otherwise, but it is the nature of the beast.
 

Jimbob54

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I don't think it is an accident that the two members of the Stereophile staff that I actually respect are the ones posting here. And I am sympathetic to the position that their employment puts them in. We should not have high expectations of the audiophile press, any more so than the car magazine guys. Both function as little more than external PR departments for the industry interests. We can wish otherwise, but it is the nature of the beast.
You missed Fremer's brief visit. I don't think he's a fan. The posts are still here but can't remember the handle.
 

Ralph_Cramden

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The benefit of the blue light. It gives them a sense of comfort - this is the master, sounds so good and sweet like a candy.

Developed by Kmart® in the 1960s, the blue light special campaign was instituted to increase sales. It was successful for several decades, but was phased out in 1991. Ten years later, in 2001, the marketing ploy was revived, but the return of the famous sporadic event was short-lived.
 

fredristair

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I just hope that in 10 years we will be where we need to be. Currently I stream Qobuz. I only recently and reluctantly got on the streaming bandwagon - and in fact now recognize its potential limitless and would be willing to pony up and pay for the best FLACs and WAV files,

And to pat my own head - I auditioned Tidal and Qobuz in March (through Audirvana) and it was rather obvious how nonsensical MQA is in an age of STREAMING HUGE MOVIE FILES and obviously as an attempt to hook publishers to take back the battle they lost way back when I was in college in 2000 at the HEY of Napster

I hope for a streaming solution that will recover the losses for the musicians I can only hope for them to continue to find ways to find financial support in the age of streaming and Covid-19 but MQA is not it for me - so many amazing and sensible posts in this thread!
 

raistlin65

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So here's a question about testimonials regarding Tidal Masters.

There have been many people who have compared CD versions of a tracks with Tidal Masters in sighted listening tests. And they determine the Tidal version to sound better and attribute it to being a better master of the recording.

How many of them are accurately detecting a difference because of the lossy nature of MQA, and then the cerebral cortex is jumping in with expectation bias and telling the listener that it sounds better because they want to believe that it's a better master recording, when the master may be the same?
 

RichB

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This just proves that it is possible to have a bunch of credentials and be wrong at the same time.

Correct. If you support MQA and all you have is audiophile euphonic testimony, that is not science.
There is not technical defense.

For those who have not read Archimago's writings or the RMAF, it is well worth it.

Archimago's Musings: MUSINGS: On the RMAF 2018 MQA talk, pseudonyms, and the right to anonymity.


RMAF_MQA_HowDidWe.jpg
\\

The attitude of the MQA folks is informative. ;)

- Rich
 
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levimax

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So here's a question about testimonials regarding Tidal Masters.

There have been many people who have compared CD versions of a tracks with Tidal Masters in sighted listening tests. And they determine the Tidal version to sound better and attribute it to being a better master of the recording.

How many of them are accurately detecting a difference because of the lossy nature of MQA, and then the cerebral cortex is jumping in with expectation bias and telling the listener that it sounds better because they want to believe that it's a better master recording, when the master may be the same?
On a lot of the other boards people are falling over themselves to praise the better sound of MQA.... of course few if any are blind and level matched tests so their testimonials are meaningless but people take them seriously. I don't doubt that a better source / mastering would sound better on MQA.... while lossy MQA is transparent or close enough. Unfortunately these sighted testimonials are exactly what MQA needs to fuel it fantastical claims and keep most people in the dark about what MQA really is.
 

samsa

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What you are seeing in the spectral analysis is the effect of noise-shaping. This is not uncommon. For example, following my experience of the POWR and Apogee UV22 noise-shaping algorithms, I tend to use 3rd-order noise-shaping when preparing the CD masters of my recordings. The level of the noise in the top half-octave that you show is higher than in my CD masters, but I can confidently predict that at -45dBFS it will be inaudible.


Let me make sure I understand.

This:

tosPFpUkOF.png.c63085adde34eae9a4e199ed96e37d47.png


is less audible than the ultrasonics that MQA's origami is designed to preserve?
 

John Atkinson

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Let me make sure I understand.

This:

tosPFpUkOF.png.c63085adde34eae9a4e199ed96e37d47.png


is less audible than the ultrasonics that MQA's origami is designed to preserve?

It's random noise and as such is benign at this level and with this spectrum.

John Atkinson
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Rusty Shackleford

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Correct. If you support MQA and all you have is audiophile euphonic testimony, that is not science.
There is not technical defense.

For those who have not read Archimago's writings or the RMAF, it is well worth it.

Archimago's Musings: MUSINGS: On the RMAF 2018 MQA talk, pseudonyms, and the right to anonymity.


View attachment 126247\\

The attitude of the MQA folks is informative. ;)

- Rich

The MQA folks simply decided to continually interrupt Chris with distractions about Archimago’s degrees. Then they claimed that they’ve privately rebutted criticisms of MQA elsewhere, despite the fact that they couldn’t rebut them at RMAF (or anywhere public). It was positively Trumpian.

The fact is that Stuart and other MQA folks have never disproven Archimago’s findings because they can’t. As Chris also points out, they’ve changed their story multiple times — specifically with regard to MQA being lossless.

The MQA folks don’t have the facts on their side. So they decided to interrupt and filibuster his presentation with nonsense. It was embarrassing to see adults who want to be trusted as experts behave in such an immature way.

Meridian invested millions into an inferior product that purports to solve a nonexistent problem. They need to continue the lie in order to try to salvage their sunk costs. They make Scientologists and marketers of audiophile rocks look reputable by comparison.
 
U

UKPI

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Still working my way through the messages in this thread. What you are seeing in the spectral analysis is the effect of noise-shaping. This is not uncommon. For example, following my experience of the POWR and Apogee UV22 noise-shaping algorithms, I tend to use 3rd-order noise-shaping when preparing the CD masters of my recordings. The level of the noise in the top half-octave that you show is higher than in my CD masters, but I can confidently predict that at -45dBFS it will be inaudible.

And in response to those who are concerned with the presence of ultrasonic noise, both class-D amplifiers and DSD encoding also produce relatively high levels of ultrasonic noise. See, for example,fig.1 at https://www.stereophile.com/content/super-audio-cd-rich-report-page-2

If that is dithering noise which completely decorrelates the quantization error from the signal, the total power (and therefore magnitude) of it has to be higher than the white noise with an equivalent function. Since digital audio systems have a maximum limit in its quantization magnitude, this will result in increased chance of clipping especially for modern heavily compressed recordings. This would be inaudible in almost all cases, but why use a hi-res format with this kind of avoidable flaw?

Also, does this mean that MQA limits the choice of noise shaping? With lossless formats, mastering engineers can freely choose the shape that puts more importance on either the clipping or the perceptibility of the noise (if there is any, but then again, MQA might be viable only when hi-res formats have audible benefits.).

It's random noise and as such is benign at this level and with this spectrum.
What is the definition of "benign"? If "benign" means inaudible, loss from various high bitrate lossy formats is also "benign". That doesn't mean that AAC and Vorbis are hi-res. Maybe all these controversies could have been avoided if MQA wasn't promoted as a hi-res format.

This point has been repeated a lot in this thread, but I'm gonna say it anyway. MQA has too many limitations, hurdles, and artificial opaqueness when compared to existing hi-res formats and doesn't get "compact" enough when compared to existing lossy formats.
 

restorer-john

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It's random noise and as such is benign at this level and with this spectrum.

And a CD player or D/A converter you measured which exhibited this amount of HF noise in the top end of the audible band wouldn't be called out as faulty or a broken design?
 

John Atkinson

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Here is why I don't want what MQA is offering:
Replaces CD quality with13-bit CD quality.

I am not sure where you get the impression that 3 bits of "quality" are lost. The container still has the original bit depth. But there is now a hidden data channel in which data encrypted as pseudorandom noise can be buried without reducing the original resolution of the audio data,

This is not snake oil or handwaving. Without getting into the specifics of what MQA does, creating a buried data channel takes advantage of the spectral nature of the analog noisefloor present on all music recordings.

I have made several choral recordings since the turn of the century. I always try to make the recording in a quiet hall and spend time chasing down and eliminating sources of noise before the sessions start. My microphones have low self-noise and I use low-noise microphone preamplifiers from Millennia Media. Nevertheless, there is always noise present in the recording.

Typical Analog Noise Floor.jpg


As you can see from this graph, made from a 24-bit recording of the “room tone” in the Oregon church where I made some of these recording, the spectrum of the noise is not flat or “white.” Instead it is closer to pink. The peak level is close to -70dBFS in the low bass (thanks to distant traffic noise) and slopes down at around 24dB/decade to 1kHz and with a somewhat shallower slope in the treble.

An FFT-derived spectrum of dithered 16-bit silence with the same number of FFT bins would produce a flat spectrum with all the components lying around -130dBFS. As the music is always higher in level than the noise, you can see that the only part of the spectrum that would need to be encoded with >16 bits lies between 2kHz and 30kHz. 13 or even 12 bits would be sufficient in the bass.

What this means is that a 24-bit recording of music made in this church that peaks at 0dBFS has spectral space available below the analog noisefloor. If I encode low-bit-depth data of some kind as pseudorandom noise – much easier to write than do - and add it to the 6 or 7 least-significant bits of the original 24-bit audio file, I have created a buried data channel. As the spectrum of that buried data channel is identical to the noisefloor of the recording, I haven’t reducing the resolution of the music data and there is a negligible rise in the overall noisefloor. I haven’t truncated the original 24-bit data to 17 bits or 13 bits or whatever, as has been stated elsewhere in the thread.

You don’t get something for nothing, however. As the noise floor now includes real information, albeit in encrypted form, I have increased the entropy of the file. The data can’t, therefore, be compressed as much by FLAC etc, as the original data.

This is not a new concept. Alan Turing did something somewhat similar in WWII to allow encrypted communication between Winston Churchill and FDR. Turing encoded the voice message as, IIRC, 8-bit audio data then buried it in a recording of random noise. When the message was transmitted, anyone listening would just hear noise. Decoding the message depended on the receiving station having exactly the same recording of random noise. Subtracting the noise signal from the received transmission reconstructed the original voice recording. (For transmission the noise was played from a 78rpm disc and for the system to work, a copy of that disc had first need to be flown across the Atlantic.)

In the 1990s, the late Michael Gerzon worked with Peter Craven (now with MQA) on a similar subtractive dither scheme with a buried data channel intended to increase the resolution of digital audio recordings – see https://www.aes.org/e-lib/browse.cfm?elib=7964

John Atkinson
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abdo123

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I am not sure where you get the impression that 3 bits of "quality" are lost. The container still has the original bit depth. But there is now a hidden data channel in which data encrypted as pseudorandom noise can be buried without reducing the original resolution of the audio data,

This is not snake oil or handwaving. Without getting into the specifics of what MQA does, creating a buried data channel takes advantage of the spectral nature of the analog noisefloor present on all music recordings.

I have made several choral recordings since the turn of the century. I always try to make the recording in a quiet hall and spend time chasing down and eliminating sources of noise before the sessions start. My microphones have low self-noise and I use low-noise microphone preamplifiers from Millennia Media. Nevertheless, there is always noise present in the recording.

View attachment 126313

As you can see from this graph, made from a 24-bit recording of the “room tone” in the Oregon church where I made some of these recording, the spectrum of the noise is not flat or “white.” Instead it is closer to pink. The peak level is close to -70dBFS in the low bass (thanks to distant traffic noise) and slopes down at around 24dB/decade to 1kHz and with a somewhat shallower slope in the treble.

An FFT-derived spectrum of dithered 16-bit silence with the same number of FFT bins would produce a flat spectrum with all the components lying around -130dBFS. As the music is always higher in level than the noise, you can see that the only part of the spectrum that would need to be encoded with >16 bits lies between 2kHz and 30kHz. 13 or even 12 bits would be sufficient in the bass.

What this means is that a 24-bit recording of music made in this church that peaks at 0dBFS has spectral space available below the analog noisefloor. If I encode low-bit-depth data of some kind as pseudorandom noise – much easier to write than do - and add it to the 6 or 7 least-significant bits of the original 24-bit audio file, I have created a buried data channel. As the spectrum of that buried data channel is identical to the noisefloor of the recording, I haven’t reducing the resolution of the music data and there is a negligible rise in the overall noisefloor. I haven’t truncated the original 24-bit data to 17 bits or 13 bits or whatever, as has been stated elsewhere in the thread.

You don’t get something for nothing, however. As the noise floor now includes real information, albeit in encrypted form, I have increased the entropy of the file. The data can’t, therefore, be compressed as much by FLAC etc, as the original data.

This is not a new concept. Alan Turing did something somewhat similar in WWII to allow encrypted communication between Winston Churchill and FDR. Turing encoded the voice message as, IIRC, 8-bit audio data then buried it in a recording of random noise. When the message was transmitted, anyone listening would just hear noise. Decoding the message depended on the receiving station having exactly the same recording of random noise. Subtracting the noise signal from the received transmission reconstructed the original voice recording. (For transmission the noise was played from a 78rpm disc and for the system to work, a copy of that disc had first need to be flown across the Atlantic.)

In the 1990s, the late Michael Gerzon worked with Peter Craven (now with MQA) on a similar subtractive dither scheme with a buried data channel intended to increase the resolution of digital audio recordings – see https://www.aes.org/e-lib/browse.cfm?elib=7964

John Atkinson
Technical Editor, Stereophile

What’s the point? Why go through all this effort for a process that (at best) will provide no audible benefits at all?

MQA is yet to provide a single evidence based advantage of using MQA. Home audio is not an encrypted message and it’s not WW2 anymore.
 
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