MQA: FINAL "Final" comments... Simply put, why I don't like MQA.

Looks like an interesting art exhibit :-).

I know... I said the previous post was "final". But I just had to kick the horse one more time. :-) Seriously, if you're sick of MQA chatter already, don't bother reading this - you've been warned!

This past week, I added my views to this thread on Computer Audiophile (from about page 198 in an epic thread with >5000 comments!). I know that forums can get pretty heated and ugly, but it is good fun sometimes so long as you don't let it get personal - it never has to, we're talking audiophile stuff after all - first-world problems, nothing life or death. Since forum threads and comments tend to get lost easily, I thought it would be reasonable to just enumerate some main talking points in the hopes of furthering clear debate (if still necessary)...

Suppose we start with an original 24/192 hi-res file which I think most of us would agree would be able to encode all that human ears/minds can perceive and likely more (sure, we can argue this point but remember that few recordings are even true 24/192). Now, suppose we want to stream this because that's the music distribution model we see growth potential in and we want to decrease the data rate to an equivalent 24/48 file (as per TIDAL's target data stream) as a reasonable Internet transfer speed.

We have 2 options currently:

1. We simply downsample to 48kHz while maintaining 24-bit resolution and give up the ultrasonic frequencies above 24kHz = STANDARD downsampling. 

2. We sacrifice 24-bit depth to "typically 15.85 bits" (Bob Stuart's words), and encode the ultrasonic frequencies from 24-48kHz in a lossy fashion = MQA encoding & decoding. [Throw in some stuff about "de-blurring" while you do this of course and claim you can recover everything else you "need" back to the "original" 192kHz. Turn on a LED/indicator telling us MQA decoding is happening, that there's no error in the stream and it's the "original" resolution (meaningless, but that's fine).]

Which of the 2 do you choose? Do you think there's going to be a massive difference in sound quality?

Personally, I think Option 1 is just fine and have said this from the beginning. Lossless 24/48 audio sounds great and in many cases would be easier to compress than MQA for streaming. Heck, we could zero out the last 4 bits and maybe compress a 20/48 stream for more data savings without worrying about anyone complaining. Plus, since time domain performance is linked with bit-depth, one could argue that maintaining true 24-bit resolution provides better time-domain performance below Nyquist. It will be "open" for easy adoption by manufacturers and not impose any licensing fee.

But TIDAL and MQA presents to us option 2. Here are my concerns:

1. It adds complexity and cost (unnecessarily):

a. We already have many high-resolution DACs out there. Do we need a new "format" that's not "fully" backward compatible?

b. Only MQA-certified software / hardware available for decoding. This reduces options for consumers and likely always will especially in the audiophile world where small manufacturers may find it hard to justify licensing costs. Furthermore, small independent developers, free software and Linux distributions would not be able to develop for MQA decoding unless under some kind of license. Ultimately this reduces innovation.

c. MQA versions of downloads such as what we see on 2L (US$19 for 24/96, $23 for 24/192, $24 for MQA, and $30 for studio master DXD) often costs more than downsampled very high quality 24/192. Does MQA encoding actually add any value or are we seeing the added licensing fee passed on to consumers? Is there any justification for the existence of MQA for file downloads when we're not faced with the bitrate limitations of streaming over the Internet?

2. Technical concerns:

a. It reduces the actual bitdepth to the aforementioned "typically 15.85 bits" and up to "17-bits" resolution when decoded. These numbers are from Bob Stuart. I know they want us to ignore this and focus on the analogue output rather than care about the digital technical values. We can argue about this of course; but the point is that a resolution limit has been imposed which is lower than standard 24-bit digital audio.

b. Reconstruction of the first unfold into the 24-48kHz audio frequencies is lossy in nature compared to the original. Again, they may argue that there is no audible difference, and yet again, a limitation has been imposed that would not exist with 24/96, much less from a 24/192 source.

c. MQA upsampling is done with "leaky" filters resulting in weak ultrasonic suppression of imaging above Nyquist. Remember that DAC designers can easily program their devices to do this if felt to be preferable for their designs. Also, we as consumers can choose to do this ourselves with software upsampling if we really think this is a good idea (software like HQPlayer perhaps or even SoX).

d. For those who want to do advanced DSP like room correction filters, ambisonic processing (like this one), or surround processing, we cannot have access to the full digital resolution because of the proprietary MQA decode process. (This is a big deal IMO that limits flexibility and progress as we aim for better sound quality for hi-fi enthusiasts.)

[Given the technical concerns, what is the meaning of advertising claims of "de-blurring", how can it "fundamentally change the way we all enjoy music", represent a "new paradigm", or "reveal every detail of the original recording"?]

Update - February 2018:

e. The MQA system may in fact add group delay and "blur" the audio, worsening the potential for transients to smear due to the fact that they're using non-linear reconstruction filters. Even if this is accounted for in the encoding step, the compensation would distort playback without an MQA decoder/filter. Clearly, a DAC should ideally not use the MQA filter by default except when the data is specifically encoded for this type of playback.

3. Minimal audible difference:

a. Digital subtraction tests show little difference. 

b. Blind listening test with 83 listeners show no clear preference. (In fact, in some situations, standard hi-res was preferred.) 

c. Inter-DAC comparisons with MQA decoding show no evidence of significant "authentication" of a standard "studio sound" in the analogue output beyond the expected DAC differences.

4. Unclear Digital Rights Management (DRM) implications:

a. Already as in (1), MQA certified products such as an MQA DAC adds expense and there are fewer software playback options. It locks us into a proprietary mechanism right from the start. This is a backward step considering the years of open and free (for consumer) lossless file formats like WAV, FLAC, ALAC, WV, APE, etc...

b. Potential future stronger mechanisms such as encryption or scrambling to enforce playback only with licensed products at the expense of significant sound quality if one does not "buy in". This is not an issue currently if you feel undecoded MQA sounds as good as CD resolution. However, there are hints in the MQA firmware that more severe forms of DRM can be imposed. It doesn't take a genius to see how that MQA "authentication" indicator can be linked to such a mechanism. Do we even need to entertain this possibility as consumers in 2017 after years of rejected attempts at DRM and digital watermarking?

I might have missed other arguments but these are the top-of-mind for me. I'm certainly happy to be wrong if evidence can be provided and explained how some of the technical pitfalls like item 2d can be circumvented without loss of resolution.

Just like with the TAS articles recently, when we look at forum debates, one essentially never finds evidence-based arguments in favour of MQA (like the Danny Kaey video from Rocky Mountain Audio Fest last week as well). IMO, unless the proponents can look at that list above and provide clear answers, it's really not much of a discussion, is it?

Even worse I think is when proponents avoid the evidence and facts, instead start using a pejorative tone like calling those arguing against MQA "malcontents" in a debate or resorting to a mindless philosophy of "Are you having fun?" to substitute for valid points. I trust as adults, our emotional and intellectual lives are more nuanced, complex, and capable of grasping grander values, concepts and desires. Even if we think "it's just audio", the way one argues tells us a bit about the depth of the person that we are.

Unless we get past these issues, we'll just continue to talk past each other primarily with opinions and idiosyncratic ideas rather than simply face up to what MQA is and what it represents; a closed vision of "studio sound" as presented through the business model and technical lens of MQA Ltd. Accessible fully only thorough devices and software licensed within their controlled proprietary mechanism.

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Hopefully this FINAL "final" post on MQA wasn't too painful for everyone. I'm done.

Alright folks, I'm literally getting ready for my flight overseas as I post this :-). Looking forward to some warmth, sunshine, good food, sights, sounds and stimulating discussions with friends and colleagues.

Have a wonderful few weeks and I hope you're all enjoying some great music!

ADDENDUM:

Fascinating comment from Charles Hansen of Ayre. He has been an outspoken opponent to MQA from within the audio industry for awhile. And a critic of the industry's direction - check out this post particularly along with the rest of that thread addressing the audiophile press! Holy smokes.

It's one thing for consumers like myself to express criticisms of what I see. But there's certainly another level of courage needed to say what must be said as a well-known insider member of the industry.

ADDENDUM 2:

Wow. Quite the "industry insider" weekend...

Here's Bruno Putzeys on Facebook discussing Bob Stuart's MQA AES 2017 presentation that just happened this past Friday! Brilliant comment - a stab right at the heart of the technical issues...

Hmmm... "No Scientific Tests Were Done, Says MQA Founder" :-)

Any bets as to whether this would ever show up on the pages of Stereophile or The Absolute Sound or What Hi-Fi? or Hi-Fi News & Record Review? Have they ever asked Bob Stuart or company representatives questions about this over the years? Plenty of opportunities since December 2014, right?

ADDENDUM 3: (November 7, 2017)

Just wanted to add with a comment I made to Charles Hansen on AudioAsylum. Might be of interest to readers here...

Greetings from Shanghai, Charlie, 

Just wanted to add given that you're also a manufacturer... 

I think we all appreciate the importance of making money! Nothing wrong with capitalism, corporations, and the profit motive of course. When companies make good products, this is to be lauded and rewarded. 

The issue IMO with MQA is that it's bogus. It was marketed in a bogus fashion, it is not capable of what it claims, and even if we don't call it all-out DRM, they have not addressed the observation of such an underlying intent or to clarify what limits they seek to protect consumer interests. 

This is IMO bordering on fraud (again - this is my opinion). There are IMO lies being spoken of in the advertising and claims. When this happens, then absolutely, as audiophiles and music lovers, we must come out fighting against such nonsense whether perpetuated by the company itself or in the moronic audiophile press. 

As audiophiles, I think we can all find and see products being advertised demanding that we be skeptical of. For the most part, we can probably just let it pass... But in the case of MQA, there's a real threat here of that corporate "greed" infecting the music production and distribution chain that provides NOTHING to the consumer; in fact, it's counterproductive for the consumer. This is a major problem with MQA and again, demands thoughtful audiophiles to respond in kind.