Roon core decode 16 bit MQA to what?

Audio Gear Talk MQA
27

Well we just have to agree to disagree.
That several others don’t understand the purpose of a MQA decoder that receive a file where the original encoded MQA file hasn’t been applied the ogami process, doesn’t make your understanding more right.

That the decoder displays a transformation from a 16 bit MQA 44.1 to 24/88,2, does not mean that this is actually is happening. It is actually impossible by definition of how MQA works. MQA decoding has never been about upsampling. Or exchange the bit depth from 16 to 24.
MQA only use the file (original master) supplied by the studio.

My only point is that what is displayed in Roon is wrong. Roon officials haven’t so far said this information is correct or not. I’m looking for a simple confirmation. The closest we (or at least I) comes to an explanation is Bob’s latest posts about some errors.

I asked for documentation confirming your understanding. You won’t find.
You may find the opposite under:

28

That article does not say anything about what MQA does or does not do in terms of it’s own decode processing.

It is speaking of Authentication and trying not to prevent previously upsampled files from being processing into an MQA file. But, they acknowledge that it is not simple, so they can’t really guarantee that a file they receive from a label has not been previously upsampled.

29

Furthermore, upsampling is not anathema to MQA. Rather, upsampling is inherent to MQA. As has been shown in published works, rendering is upsampling.

AJ

30

It’s my understanding that they can and do check, and have tools to for the purpose. That’s as close as anyone will achieve over the vast catalogue and no one else is going to any lengths to authentic anything…

31

The DAC playback sample rate.

The “original” means the master used to create this MQA music. The “transmission” rate of encoded MQA file is always 44.1kHz or 48kHz from Tidal.

(I have done MQA integration using 7 models of DAC chips from 4 semiconductor manufacturers.)

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32

We know from MQA site, that there is no unfolding implement is this file. Agree ?

We can close this discussion once and for all if you or @danny confirms that Roon core decoder perform upsampling of a 16/44.1kHz file.

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MQA 16/44.1 is the final clue as to what is really going on with MQA and Tidal and what this is really all about. It’s a rent seeking solution looking for a problem, driven by a massive marketing/PR grift that benefits… who?

35

The album art below shows the ‘FLAC 44.1kHz 16bit, MQA 44.1kHz’ is actually file tag information.

Encoder MQAEncode
ORIGINALSAMPLERATE 44100

If you tag the above to a non MQA file, Roon will display it. Of course when you try to playback, the signal path will a normal PCM :smile:

Why MQA decoder must output 24/88.2/96k irregardless the source has to do with MQA filter applied during the encoding stage. Any filter applied during encoding process requires 2x OS to achieve the desired filter response at the end. This is similar to oversampling digital filter.16bit to 24bit output increase the precision so that the filter will perform better. Since the output from MQA decoder is already 24/88.2/96k, normal DACs without MQA rendering will perform better in preserving the impulse response. It will bypass the first stage of OS filter (usually the most steep, i.e, 44.1/48k filter) followed by a more gentle filter response in the conventional DAC

Not much is known about MQA rendering process but my guessed, even DSP can be applied after MQA decoder by first taking out the renderer information and later put back, means, the renderer does not depends on the musical data but the renderer bits which is set during the encoding stage. This rendering bits are used to select the different type of MQA filters that match the characteristics of the DAC types. As I said before in order for the filters to work, oversampling must be applied. Meaning the rendering stage is actually selection of filters and oversampling. The whole process of doing this is to improved impulse response and MQA processing is behind all this.

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36

Music doesn’t contain impulse responses, and if it did, it would be equivalent to out-of-band frequencies – not something you’d wish to preserve!

Basically, 16 bit 44.1 kHz MQA is basically being up-sampled. Whomever posted that it was a “first unfold” cannot be correct, though MQA has played fast-and-loose with its own terminology, claiming up-sampling was unfolding. If they state anywhere that this up-sampling of 16/44.1 files is unfolding, given that the “origami” technology involves embedding a compressed version of the inaudible high-frequency parts of a high-res audio file, then they are lying about their own technology.

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37

They could be folding some of the 16 bits in the audible band to accommodate the couple of control bits that are needed. If not, then, it is not even 16 bits.

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38

As I’m mainly interesting in what actually the decoder do, and would not participate to much in discussion in how many bits, I think it’s been said by Bob Stuart that it’s 15 bit something

However my understanding from reading Bob’s talk, it’s clear to me not all files go through the origami process. He is hiding this a bit in his explanations, and he doesn’t talk much about decoding. Only encoding.

Does any question this understanding about encoding ? This is important to agree upon, as else I can totally understand why some is finding this questioning what a MQA decoder of a MQA 44.1 file does, quite idiotic.

Also you need some bits to create the unfolding. I can’t se one bit is enough.

The transportation rate can maximum be 24/48. That container can contain anything from an MP3 file (not relevant for MQA presently) to a 24/352,8 (or the double) and also 32 bit. Roon displays the final decoded rate that should be expected (by a MQA DAC = original file), in their information about the MQA file. This I hope everybody agrees on. If not we’re into another endless discussion about what Roon displays (MQA metadata).

So a 16/44.1 cannot be folded down to something if we should follow MQA terminology, as the intention was to take hi-res files and fold.
And as it’s displayed as MQA 44.1 kHz, it cannot be doubled to 88.2 in order to obtain an original MQA of 88.2. (Again the decoder displays 88.2 on an authentication of 44.1).

However it can be upsampled. An experiment with no MQA DAC’s and MQA DAC’s with all the MQA settings tested in Roon, shows that Roon what so ever, will display 88.2, even if the DAC states 44.1.
So the DAC must be down sampling. (Unless Roon displays wrong).

If I should make a guess, MQA is adding some sort of filters to the original 16/44.1 digital master, and out comes a MQA 44.1 kHz.
But all Roon has to do is to admit they’re upsampling, (cause filters apply earlier makes this necessary).

As all MQA decoders use the same filter, and @wklie already has confirmed that this MQA SW is also used by Lumin, and he more or less confirms the MQA 44.1 file has been upsampled, we should conclude that the MQA decoder in general, is upsampling all files below 96kHz. (MQA encoded files).

One can speculate the reason for this, but I think answers probably has been given. (Filters).

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39

Roon really has to admit nothing, and further, a NDA with MQA Ltd. is probably preventing them from saying upsampling.

Roon personnel have already told you that they have implemented the core decoder to MQA’s specification. So it’s MQA that has to admit what their core decoder is doing, and what we know of MQA so far is they only admit in marketing buzz words.

40

Really? Well try changing your DAC output filters may be you can hear some different. Different filters have different impulse response! Filters have two characteristics; how fast it rolls off govern the impulse response, the so called ‘ringing’ whether it is music or test signals. Our hears are more sensitive to pre ‘ringing’ then frequency response… ‘out of band noise’:grinning:

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41

The original question, Roon core decode 16 bit to what?

A:- Lovely Music :joy:

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42

Streams well and sounds great.

43

Almost all digital audio streams well and sounds great these days. No MQA necessary.

AJ

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44

But, if you use Tidal and have multiple MQA DAC’s, then why not?

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45

Principles. Some find MQA’s technical justifications (or lack thereof) and business practices objectionable.

AJ

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46

I have just one principle, no pineapple on pizza. Everything else is mutable :wink:

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47

Yes, we get that. I find that silly.

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