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MQA compression

Connecting Hauptwerk to MIDI organs, sequencers, ...
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Jan Loosman

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MQA compression

PostTue Jan 06, 2015 12:53 pm

Meridian developed a revolutionairy compression codec.

The intention is to use this MQA technique to create files that actually capture all the relevant information on the original master recordings, and it's apparently actually possible to package a complete album in a file that's small enough for downloading or even streaming. He claimed that MQA coding enabled material equivalent to HD quality to be streamed at just 1Mb/s (i.e. no higher than standard CD rates).

https://www.meridian-audio.com/sounds-t ... -but-true/
http://www.theabsolutesound.com/article ... idian-mqa/

Is this codec usable for Hauptwerk in the future? Thus giving us more diskspace? And load greater /higher resolution samplesets in computers with limited memory?
This may be a development to follow.

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RichardW

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Re: MQA compression

PostTue Jan 06, 2015 1:34 pm

Hauptwerk already has a "compression" option although I don't expect it would be exactly like the Meridian one.

The problem is that with computers there is always a space/time trade-off. If you save space you usually need more CPU time and if you can reduce the CPU time you often end up using more space.

Compression is like that. The more you compress the data the longer it takes to reconstruct it. This will affect polyphony.

The other problem is that most codecs are not constrained by problems of latency. If you load a CD and it takes 10 seconds to start then streams perfectly well then you probably would not have a problem. On the other hand, if you had to wait 10 seconds between every key depression and a sound appearing at the speakers then you would.

If you want to save RAM as well as disk then the unpacking requirements would be enormous. Remember, the reason HW uses RAM is because disk is too slow. If you add a decompression algorithm to all the other mixing and fading operations this will slow the processing back down. I don't think it would be practical.

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Richard
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ldeutsch

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Re: MQA compression

PostTue Jan 06, 2015 3:50 pm

As a Hauptwerk user who is also knows something about the mathematics of data compression (as a big part of my day job) I felt the need to chime in on this.

I had not heard of this Meridian MQA technique so I had to search online to find out. There are two problems - first, in mathematics, the acronym MQA usually stands for "modified quasilinearization algorithm" which is a technique used to pseudo-optimize control algorithms. It turns out the Meridian is NOT using this definition. Instead, their MQA stands for "Master Quality Authenticated!" Once I figured that out, I learned that because this is proprietary technology, I was not going to find out anything real about how it works.

However, I can say a few things ARE true. There are two major kinds of compression algorithms: lossless and lossy, though I hate the latter term. All algorithms are optimized to preserve the most important parts of the original signal relative to the application in which they are used. The Meridian MQA appears to be a lossless algorithm, which means that in the absence of noise and with infinite latency, it will reproduce the original signal to the accuracy of the sampler that is used in the system.

Having said that, there are lots of such lossless algorithms that have been optimized for audio signals - meaning that they completely reproduce the original signal under the same constraints. The main figures of merit are the compression ratio (how much smaller they make the signal in terms of bits) and latency (how much delay they introduce.) I can find no published results on the Meridian algorithm to compare. However, the compression ratio is limited by the entropy in the original signals (how random they are). For audio, this results in about a factor of ~two compression - regardless of the algorithm. Some algorithms trade these off, for example a very low-latency algorithm might achieve only 40% bit reduction.

The compressor used in HW certainly has reasonable latency, so I do not expect switching to a different one will make any significant change to the responsiveness of HW. Because all the various algorithms have about the same compression ratio (and because there is no magic here) I don't see this new one resulting in any significant change to the amount of RAM or disk space required for an organ.

The claim to fame for the Meridian algorithm seems to be something other than compression ratio or latency. They are claiming some sort of authentication mechanism that can trace the various operations performed on the file so that by the time you hear it, you can trust the intervening steps. This might have value in developing HW sample sets, I suppose.

Les
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Master Quality Authenticated (MQA)

PostSat Apr 23, 2016 2:06 pm

Hi;

This is a shout out to everyone but especially to the sample set producers about a new audio technology that addresses the shortcomings of current state of the art digital recording/playback.

The shortcomings are that the filters which are necessary for current digital audio blur the signal in the time domain. Standard CD has a 5ms inaccuracy and 192kHz will have around 500us. It turns out that human hearing is very sensitive to time domain distortions and there is now a way to reduce this problem in digital audio to 10us throughout the entire spectrum. It's called Master Quality Authenticated or MQA.

My brother sent me some articles from The Absolute Sound audiophile magazine where the technology was reviewed and explained. I'll avoid all the superlative language the reviewer used to describe the sound and just say that we could expect to hear greater detail in areas like chiff and higher frequency harmonics.

The technology maintains backward compatibility with all existing hardware. It is also possible to apply the MQA process to existing recordings (even while converting analog tape over to digital) and notice significant improvements to the sound over non-MQA (read as existing) hardware.

Of course the best results are obtained from high sample rate/ long word length recording/playback using hardware that is MQA compatible. This is because metadata about what parameters were chosen during the recording process are embedded in the final product and when played back, complementary parameters are applied by the playback device to null out issues that would negatively affect the sound. Pretty amazing stuff.

Of great interest to streaming audio services like Tidal is that MQA audio information can be delivered at low bit rates (like <5Mbps) so slower internet connections can carry a high quality product to customers. Again, pretty amazing stuff.

The reviewer spent a lot of words explaining how the sound stage was more clearly defined than he'd ever heard from digital audio in the past. He sent various recordings he knew very well in to have the MQA process applied and listened to them over different systems he has and was astounded by the improvements. Some may argue that an organ, being by its very nature diffuse, doesn't require a "sound stage" and so this technology won't be all that much of a boon to us. I'm thinking that the sound will be much truer to what was presented to the microphones at the time of recording and that we will definitely notice the difference when heard with and without MQA applied.

So I've basically spilled all of my understanding in this post so asking me questions will not help you folk learn anything more. I'd suggest if you are interested in learning more about MQA that you dig around on the internet.

What I'm really hoping for here is that sample set producers will respond about their plans to incorporate MQA technology into their sample sets as it is the future of digital audio.
Brooke Benfield
Organist, Gethsemane Lutheran Church
Portland OR
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Jan Loosman

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Re: Master Quality Authenticated (MQA)

PostSat Apr 23, 2016 4:13 pm

Hello Brooke

In a earlier post i already asked about this promissing technologie.
viewtopic.php?f=3&t=13793&p=102043&hilit=Mqa#p102043
This might be ideal for Hauptwerk but i guess Martin has to buy a license which will ad to the price of a Hauptwerk license.

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Re: Master Quality Authenticated (MQA)

PostSat Apr 23, 2016 5:56 pm

Hi Jan;

I believe licensing could be something that would affect the price of Hauptwerk. I also see it affecting the sample set producers, the manufacturers of audio interfaces and all of us who will see it in the cost of everything involved the consumption of digital audio.

I think it will end up being everywhere and, eventually, inexpensive.

The reviewer had a special MQA player that cost $22,000.00. He also reviewed one that cost $299.00 and was quite good.

I went back to the thread you provided and much of the discussion there was about data compression. Although that is important for many commercial interests I want to again stress that for us, the benefit is the correction of time domain related smearing that is present in conventional digital audio.
Brooke Benfield
Organist, Gethsemane Lutheran Church
Portland OR
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mdyde

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Re: MQA compression

PostSun Apr 24, 2016 4:03 am

[I've merged this new topic onto the original topic on the subject.]
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.
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Jan Loosman

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Re: MQA compression

PostSun Apr 24, 2016 4:33 pm

Hi Brooke
http://www.dirac.com/live-home-professional-audio-info/
Dirac room correction software also corrects time domain problems. This results in a increased clarity which i can confirm, using this software. So if you are eager to correct these problems you could check out Dirac software.

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Re: MQA compression

PostMon Apr 25, 2016 6:13 am

Hi, Brooke.

I agree strongly with Jan concerning the advantages of Dirac processing.

See viewtopic.php?f=17&t=13968

Don
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brooke.benfield

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Re: MQA compression

PostMon Apr 25, 2016 9:23 pm

Hi Jan & Don;

I've read with interest the posts regarding Arc2 and Dirac and was considering using one or the other on the HW organ in the church where I play. The very real and valuable improvements these products offer, as I understand it, are achieved through frequency equalization and adjusting the timing of when the sound arrives at the listener.

MQA does not address those sorts of issues. MQA fixes the temporal smearing present in a digital audio file of, for instance, a single pipe. The energy at any given point on an analog waveform ends up being distributed (smeared) over multiple sample points when recorded with current digital audio technology and MQA fixes this issue.

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Brooke Benfield
Organist, Gethsemane Lutheran Church
Portland OR
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Jan Loosman

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Re: MQA compression

PostTue Apr 26, 2016 1:47 am

Hi Brooke

It's a bit confusing. Dirac corrects in the time domain afterwards and MQA in the time domain at the beginning of the chain when compressing the sound with MQA algorithms if i understand well?

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Re: MQA compression

PostTue Apr 26, 2016 3:52 am

Hi Brooke, I'm not an expert at all, but since MQA is an compression algorithm and since Hauptwerk (in principle) uses uncompressed WAV's, what would be the benefit in sound quality?

(I can see a potential benefit in reduced RAM requirements)
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Re: MQA compression

PostWed Apr 27, 2016 12:01 pm

Hi Jan;

I agree, it's a bit confusing but your comparison of Dirac correction time domain issues happening afterwards and MQA at the beginning is accurate, as I understand it.

Hi Josq;

The benefit in sound would be that the end product would be a closer match to the actual analog waveform the microphones picked up. In standard CD (44.1kHz sample rate) format a sample/conversion happens every ~22.67us. In this form of digital audio there is an inherent time domain misalignment of up to 5ms which means energy from a given point in time on the original analog waveform could show up +/- 110 samples away from where it should be in the digital form of the signal.

So, imagine the fine details of the sound of wind in an organ pipe or the complex transients of chiff being spread over adjacent samples rather than happening when it should in relation to the fundamental frequency of the waveform. MQA fixes this problem.

I'm not sure if MQA was implemented in Hauptwerk if we would be having RAM loaded with compressed or uncompressed waveforms. I also don't know if there will be significant latency if the decompression happened in real time.

The reviewer in the articles I read had a $22,000.00 MQA player. He also reviewed another MQA player which was only $299.00 and it had a DSP chip in it capable of more than 1000MIPS (I think MIPS is the correct acronym). Would we see latency with that much computer horsepower working on the problem? I don't know.

Regards.
Brooke Benfield
Organist, Gethsemane Lutheran Church
Portland OR
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Jan Loosman

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Re: MQA compression

PostWed Apr 27, 2016 3:15 pm

https://www.youtube.com/watch?v=r_wxRGiBoJg
This link was provided on the Dutch forum by Peter.
Very interesting.
Brooke you mentioned latency. If this technology gives to much latency then this would be a no go for Hauptwerk. If latency is no problem this could be a very suitable technologie for Hauptwerk.

Regards Jan

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