Your Chance To Ask Bob Stuart Anything About MQA

[The Computer Audiophile]

Your Chance To Ask Bob Stuart Anything About MQA

 

Hi Guys - I know there is a lot of confusion surrounding MQA. The MQA at CES thread has over 30,000 views and tons of speculation. In an effort to help get to the facts and educate people about MQA, Bob Stuart has agreed to answer questions from the CA Community. This includes questions from complete beginner level to how ever advanced you want to take it.

 

Here's how this will work: The CA Community will post questions in this thread. I will curate the thread to keep it on track, removing non-questions and off-topic comments. I won't remove any questions. After a period of time I will collect the questions and send them to Bob Stuart. Bob will answer the questions, and I will publish what I receive from Bob as a Q&A on the front page of CA.

 

I believe crowdsourcing these questions will be much more beneficial than a simple interview or article about MQA. This is a great opportunity to get answers direct from the source.

 

Please keep your questions as succinct as possible. I realize some questions may need a bit of background or subjective/objective data as a preface, and that's OK as well.

 

After this, there's no saying, "I wish someone would ask ..." This is your chance :~)

[esldude]

Okay, I'll try a few.

 

Will software decoding be allowed (and when)? Will software decoding get the complete benefit that will be possible with hardware MQA DACs? If not what will the differences be?

 

Is MQA lossless in the sense of the data? Not is it audibly lossless, does it have the ability to unpack the exact data that was recorded at higher sample rates?

 

The MQA process is said to be able to improve upon the original recording by de-blurring. How can this function with the common recording that has had many levels of processing between the recorded data and the end result?

 

MQA is said to playback without decoding with good quality or improved quality over a non-MQA redbook file (or is this true), what are the differences between non-decoded MQA files that were originally 192/24 and a simple quality downsampling of 192/24 to redbook specs of 44/24? Do non-decoded MQA files still have 16 bits of resolution or is it reduced to 15 bits or less? Will there be more noise from the MQA process when playing back un-decoded MQA files?

[new_media]

Thanks for the opportunity, Chris.

 

I think that a lot of people are concerned about the "walled garden" aspect of MQA.

 

My understanding of the MQA process is that when the files are encoded, corrections are made for "damage" done by the original ADC.

 

What advantages, if any, do compression and back-end decoding have with respect to sound quality? In other words, wouldn't we be just as well off with hi-res files that have had the original encoding errors "fixed?"

[Distinctive]

Nice initiative.

 

Here is my question;

If my understanding is correct, DAC profiling would imply that the DAC model in question has to be sent from the manufacturer to Meridian for certification. Is this really a viable route from an IP standpoint and a practical way of doing it? Seems like a cumbersome and time consuming procedure in my view.

[JohnSwenson]

I have a DAC I built myself with a custom filter implemented in an FPGA which upsamples to 352.8/384 which turns off the internal filter in the DAC chip. How will MQA work with such a DAC? I have spent a LOT of effort getting this filter in the FPGA just right, will MQA be messing this up and adding what IT thinks is the best filter?

 

John S.

[miguelito]

Great!

 

1- What will be the dynamic range of a 24bit/48KHz MQA file? Will it be 16bit since the least significant 8 bits are used to encode the higher freq data?

 

2- Will software decoding into a "standard" high res bit stream that a generic DAC can use be allowed?

 

3- Will room correction be usable with MQA?

 

5- I understand how authentication for a simple recording where one ADC was used could work - but how would this work for cases where multiple different digital sources, from many different ADCs are digitally mixed?

 

6- Why would TIDAL use MQA for anything but hi-res content? Redbook files (16/44) would be substantially bigger in MQA form so no upside on bandwidth.

 

7- What does "MQA from the master" mean? Does it mean the final digital master is processed through the MQA encoding or does it mean MQA is used in the mixing process?

 

8- What approx fraction of the music catalog has provenance information?

 

9- What does DRM mean in the context of MQA?

[orgel]

Are streaming services that have embraced MQA (e.g., Tidal) likely to be MQA encoding Red Book material? If so, what is the benefit of doing that?

 

--David

[Jud]

- Do I understand correctly that MQA can work in part by encoding information from a higher resolution file into high frequency noise in a lower resolution file?

 

- Do you have measurements for what the level of increase in noise is at what frequencies due to this process, either typically or in at least one actual example of conversion from a 192/24 file to 48/24 or 44.1/24?

[eganz]

Will you release the detailed method to unpack an MQA file?

 

Eric

 

 

 

Note: Reformatted as a question. -CC

[R1200CL]

1. Can you explain the difference between MQA and MQA Studio ?

 

2. Can MQA be multichannel ?

 

3. Will or can MQA be transported as 32 bit ?

 

4. Is 384kHz the highest MQA encoding frequency?

 

5. How will the end user know original master resolution ? Is there some requirements from MQA, so as an example we easily will know if the master is 16 bit, even it is delivered as 24 bit.

The question applies bothe to DAC's, SW Solutions, streamers, CD's, and downloaded MQA.

You may also use your answer to DAR site as an example, where you talk about 3 types of encoding of 16 bit material. (In comment field). And also to distinguish between 96 and 192, and more.

 

6. From MQA FAQ, I understand there is a license pr. unit. (DAC, Streamer, and other hardware). Can you explain about license principles for SW. Like should we expect to pay more for a SW player that support MQA ?

And maybe Tidal as well.

 

7. Which leads to a freeware player, will they ever be able to play MQA ? If you could pay some attention to a possible MQA implementation for Squeezeboxes ? Like is there a license issue that would or could stop a Squeezebox support ? (With spdif or USB out).

 

8. How many DAC profiles do you currently support ?

 

9. Any number of planned DAC profiles to be supported ?

 

10. Is a DAC profile only related to the chip, like it can be used for many brands, or will a DAC profile be pr. DAC manufacturer and model ?

 

11. The success of MQA depends on the record companies. Can you explain how much effort we can expect them to put in to this ? Like remastering (Whatever that means), a purely automatically process. (Your FAQ talks about 100 000 tracks in 24 hours).

Can we be assured we get the best masters. (Whatever best is).

Is there some sort of a new MQA standard for new productions ?

 

Like also assure us that there can ever only exist one MQA version of a master, or maybe not ?

 

I hope you take the time to explain all aspects related to the MQA production process, so there will be no more speculation about that. You may also add the Hyper Secure Module implementation, as people need to understand when and why, and maybe how, it is implemented.

 

12. What is the value for the record companies to encode millions of old files. (If they will do).

 

13. Can you talk to Pål and ask if you are allowed to tell what to expect from Tidal when they flip the switch. Will MQA versions coexisting with redbook versions. Meaning if you have the necessary access (subscription), you will be able to play both versions of a track / album.

 

14. Any comments on the content of these guys investigations ?

http://archimago.blogspot.ca/2016/01/measurements-mqa-observations-and-big.html

 

http://www.computeraudiophile.com/blogs/miska/some-analysis-and-comparison-mqa-encoded-flac-vs-normal-optimized-hires-flac-674/

[Axiom05]

If a recording is made using the MQA process, will this preclude the availability of a hi-res non-MQA version?

[R1200CL]

15. Is there any technical limitations for Chromecast Audio not to support MQA ?

 

16. If Chromecast Audio can support MQA, will you implement it ? (Both digital and analog)

Or I can ask in a different way, we know that Tidal plan to support Chromecast. Will this also be possible with the MQA enabled ? (Sometime).

 

17. Is there any technical limitations, that makes a FPGA DAC not to have MQA implemented ?

 

18. Will there exist 16/44.1 MQA files, so AirPlay and Sonos as an example is not technical limited by a 24 bit MQA requirement ?

(They could in theory benefit from those few?16 bit MQA editions).

Or could such old non hires systems be allowed to downsample to 16/44.1 ? Same way 384 is downsampled or converted to 192 by Meridian Explorer2 ?

 

19. Are there some technical minimum requirement to a MQA certified DAC ? Like 32/384, or 24/192 ?

 

20 Will spdif streamer interface be allowed, or only USB, in order to achive a two way communication. Meaning you would require a USB DAC as a minimum in order to have your old DAC benefit from SW decoded MQA, or a streamer like Auralic.

[computerilliterate]

The MQA website states that the technology "...delivers master quality audio in a file that’s small enough to stream or download." Will there be any provision for storing that file in its "small" state until selected to be unpacked for playback? That might be useful for portable audio players with restricted storage space.

[DanBoulet]

- Regarding bandwidth utilisation: what kind of bitrates can we expect to see while streaming hi-res MQA, and, on average, how much larger will the data transfer rate be when compared to that of the same material streamed as 44.1/16 lossless FLAC?

[Paul R]

Is MQA purely a technology, or is it an initiative to change music distribution? By that I mean does the MQA product include DRM or track usage in any way?

 

Do you see MQA as complementary to existing technology, as co-existing but separate, or as a replacement for any specific technology?

 

Obviously there are a lot of existing systems out there, are we looking at compatibility with iTunes, Apple Music, Sonos, etc.?

 

Are there any plans to use MQA in video releases?

[JR_Audio]

I have already mentioned my two questions on the Archimago Blog, that is really worth reading:

 

Archimago's Musings: MEASUREMENTS: MQA (Master Quality Authenticated) Observations and The Big Picture...

 

In this blog you will see, that from the technical point of view, MQA have around 13 Bit of “lossless” information and everything below 14 Bit is “lossy”. Doesn't mean that is will not sound good, it just means, that this is not a lossless codec, it is lossy (from the technical point of view).

 

Here are some Screen shots of the noise in the MQA data, compared to a plain dithered 16 Bit and to a noise shaped dithered 16 Bit stream.

 

 

But here are my two questions: Will MQA work with Digital Volume Control and also with Digital Room Correction?

 

1. If I reduce the level of the digital signal within the Playback Software to just about 1 dB (in the digital domain), will the MQA light will still lit up and will the MQA stream still be "unpacked", or will this be end up in the 44k1 24 Bit digital stream, as when having non MQA certified DAC? Nearly all playback software do still sound good, if you adjust the level of the tracks just within some dB.

 

2. My thinking is, then also no digital room correction will work in that way, that it will benefit from the MQA unpacking, and all files will end up with just 44k1 24 Bit container, but mainly only with 13 Bit of audio information, no matter what sample rate the original file has had in the MQA encoding process.

 

In comparison a lesser compressed master files with real 24 Bit 96 kHz sample rate from start to finish (in a real lossless codec) will do a more practical job, in our daily homes, especially when you plan or already use a Digital Room Correction (in the digital path, between or in the playback software, and before the DAC).

 

Also in the above mentioned blog you will find some additional comments from me, about my listening impression of the the Non Decoded MQA Listening (on non MQA DACs) and some speculations about Linear Phase and Minimum Phase filtering.

 

Juergen

[miguelito]

But here are my two questions: Will MQA work with Digital Volume Control and also with Digital Room Correction?

 

1. If I reduce the level of the digital signal within the Playback Software to just about 1 dB (in the digital domain), will the MQA light will still lit up and will the MQA stream still be "unpacked", or will this be end up in the 44k1 24 Bit digital stream, as when having non MQA certified DAC? Nearly all playback software do still sound good, if you adjust the level of the tracks just within some dB.

 

2. My thinking is, then also no digital room correction will work in that way, that it will benefit from the MQA unpacking, and all files will end up with just 44k1 24 Bit container, but mainly only with 13 Bit of audio information, no matter what sample rate the original file has had in the MQA encoding process.

+1 on these questions (I asked something similar but your articulation of the problem is way better).

 

To add a little color to these questions, I will ask point blanc:

 

1- Will MQA allow at any point a "standard" decoded high res PCM data stream to be manipulated in software for volume control or room correction?

 

2- If the answer to the above is 'No', will it be possible to have any room corrections at all in software along the likes of Dirac, etc, or will room correction be restricted to Meridian devices such as the DSP8000 speaker system?

[eganz]

Will you release a compiled program to unpack the MQA datastream, or work with others to accomplish this?

[DavidL]

Are there any plans to implement MQA on digital feeds from live broadcasts.

 

For example in the UK BBC radio 3 is streamed at 'high definition' (typically up to 320kbs): could the MQA process be applied in real time to supply CD or better quality within the broadcast bandwidth limitations?

[crenca]

DRM DRM DRM - what technical and/or legal assurances does a user/purchaser of MQA (which is an IP/patented protected technology) have that MQA will not now or in the future serve as part of a DRM system? Not interested in personal assurances, good intentions, or a simple "we have no plans for that". What LEGAL rights do the purchaser of this technology have that protects them from MQA based DRM (if any)? Since the answer is probably "none", what changes to the licensing is Meridian prepared to make to assure the audio community that MQA can never be used as a DRM mechanism?

[esldude]

Is compressed sensing used to encode MQA? Is this the reason higher bit rates can be done at the low bit rates?

 

Is the generation of subtractive dithering on playback only possible with MQA hardware?

[gmgraves]

Your Chance To Ask Bob Stuart Anything About MQA

 

 

 

If someone already has a an expensive DAC, of which they are very fond, and this DAC doesn't natively support MQA, will it be possible for some manufacturer to supply a stand-alone box "MQA un-packer" with USB and/or S/PDIF output to make existing DACs MQA compatible?

[labjr]

I'd like to know how you plan to authenticate masters when you repair old digital files and put the MQA stamp on that? I mean there's so much fraud going on already with major labels trying to pass off upsampled redbook files of unknown origin and questionable quality. Possibly even material that's been converted to digital and back to analog or suffers from generation loss due to use of non masters or safety copies etc? Why not start from scratch and require original master tapes when doing MQA encoding?

 

Quite frankly it would seem that repairing rather than starting over is an impossible task and would be diluting the MQA process to mean everything to everybody.

[grs113]

To Mr. Stuart: I read your 2014 AES convention paper #9178 with great interest. It is clear to me that MQA has great potential and considers a larger array of psychoacoustic factors than are currently acknowledged in conventional sampling/filter theory. In addition to post #10, questions 8 through 10, I would like to ask:

 

Can you please clarify how DAC sampling rate capability might affect reproduction quality, considering your paper statement that the receiver (decoder) should implement an appropriate up-sampling reconstruction? What sampling rate capability(ies) would you consider ideal for highest quality reproduction, and what other DAC capabilities would you suggest are important?

[astrotoy]

Will there be a consumer version of MQA to convert existing hirez file (like 192/24) that I have created to MQA files. I am thinking about being able to have greater portability of my files.