What is still the point of mqa compression when we see the current network capacities and the low cost of storage?
Bob Stuart, creator of MQA, claims that he has solved (digital) problems that normally are introduced to the system when using conventional digital reconstruction filters which are needed when converting the signal to analog. One of those is the pre-ringing.
You will find here in the forum a lot of (controversial) threads dealing with advantages and disadvantages of MQA.
You see, thatās the dis-ingenuousness of the whole MQA enterprise.
Originally, MQA was promoted as a way to save bandwidth. Now, as you note, that bandwidth and storage are not so much of a factor, MQA is being marketed as an SQ enhancement.
Publishing companies like MQA for the encryption it potentially promises.
Itās all a monstrous plot. 
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Interesting, that one actually doesnāt need a lossy proprietary encoder/decoder [edited after moderation] ecosystem when there are already plenty DACs using filters that eliminate pre-ringing.
Because PCM is no more perfect than any format before it? And MQA does something no-one else can replicateā¦so far. But you need ears not numbers to help you discern whether MQA has value for youā¦and there are many here who really value it. You have to make your own mind up but do not assume MQA is just about compression.
A/Some
B/None
C/Lots
Just like most of the MQA threads.
Given the fact that MQA is a lossy compression scheme on top of PCM, what can MQA do that PCM canāt?
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Yes, I have a 24/192 master. Please will someone explain how MQA will make it sound better. And transfer it in fewer bits.
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If the question is a serious one, read the extensive discussion on Bob Stuartās blog at the MQA website (also www.bobtalks.co.uk). There are also freely downloadable papers, Youtube videos, and Q&A at Stereophile. Most of us are too tired from the many previous threads on this to go through it again here.
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Thatās why I shouldāve emphasized even more the ācontroversialā nature of this topic.
And look, we even got a new thread for thisā¦.
There are DACs that use minimum phase filters to eliminate pre-ring on one of the upsampling filters in the DAC. The filters in MQA are a complementary series that removes pre-ring throughout both downsampling and upsampling chains, and also eliminates modulation noise. The issues with pre-ring are most important on the record side (downsampling chain).
Another point with minimum phase filters of the usual DAC types: they move pre-ring energy into the post-ring region where it is not without audible effects. The MQA filters based on B-splines lack any significant post-ring.
@jean_luc_Fere, MQA is a highly debated and controversial topic. I donāt see this thread lasting very long if you keep the question as wide as you have.
I suggest you re-ask the question in a more specific manner with less subjective answer possibilities, as to avoid toxicity from perpetuating here.
For example:
- does MQA actually save bandwidth?
- do MQAās [claimed] bandwidth savings matter in 2021?
- can you point me to MQAās advertised features (besides bandwidth savings)?
@moderators, feel free to shut this down if it just turns into āanother MQA threadā. We donāt need any more of those.
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Seems Archimago has addressed these issues of pre-ringing along with others like Rob Wattsā¦ Archimago's Musings: HOWTO / MUSINGS: Playing with Digital Filtering - Impulse Responses and Frequency Effects resembling Chord, Old-Skool Meridian, MQA, NOS...ā¦ As for the bandwidth issueā¦ If you are listening from a cell phone via a cell service provider bandwidth may be an issueā¦ For the rest of us listening on a home stereo system with a reasonable internet provider it is a nonissueā¦
Onto @danny 's questionsā¦
- does MQA actually save bandwidth? From Dannys end maybe soā¦ From my end, not so muchā¦
- do MQAās [claimed] bandwidth savings matter in 2021? Not so muchā¦
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How so from my end?
If I remember correctly, I think @jussi_laako actually did some tests. My gut says it doesnāt save you much once you compare FLAC 96/24 and MQA, but Iāve not done tests.
Iām not sure it actually compresses much better.
Also, 5G will soon become ubiquitous, so the bandwidth issue should be a temporary short term problem even if there is an advantage, which nothing Iāve seen says there is (besides marketing).
I donāt actually understand why Bob made it PCM compatible. Itās a cool technical idea to encode they way they do, but he would have done better by avoiding PCM compatibility.
A more apt comparison would be to FLAC 96/16 (which, is, admittedly, not a format seen in the wild). Noise (even inaudible noise) does not compress well. So, if MQA were as well-designed as the FLAC compression algorithm, you might theoretically get file sizes comparable to FLAC 96/16.
Sorry @danny, what I meant to say was streaming service providers might save some bandwidthā¦
I also agree that with 5G there should be no issues with bandwidthā¦ Although, I am unsure what world wide coverage might look like or service pricingā¦ Most of us are well beyond 300/600/1200 baud by nowā¦ 
First we need to decide if > CD resolution (> 16/44.1) is something thatās desirable.
If the answer is no then comparing 16/44.1 to MQAād 16/44.1 the MQA will often use more bits / bandwidth than other ways to deliver a stream / file at this resolution. If all we want is CD resolution then MQA is a poor choice as the way to deliver it; strictly speaking from a number of bits perspective. FLAC and ALAC do a fine job here.
If the answer is yes, then things get more interesting. Comparing > CD resolution to itās MQA equivalent (unfolded) resolution then MQA will deliver that resolution in less bits compared to FLAC and other lossless methods. There is a real savings in bandwidth and storage at this point.
So, now, letās talk about the second half of your questionā¦
In my opinion, anyone who finds > CD resolution as desirable does not have a bandwidth or storage problem. That is, if someone wants to listen to > CD resolution and canāt, that ācanātā isnāt bandwidth or storage related. The barrier to > CD resolution is not, and has not been for a few years, one of bandwidth or storage limitations.
My conclusion: There is scenario or use case where MQA compression provides a benefit at present and I highly doubt there would be a need for it in the future.
Notice, Iāve only commented about MQA compression. MQA is a lot of things and those other things may still have benefit but Iām not going to debate that here.
5G has some advantages over current LTE standards but the biggest benefit isnāt the technology. Itās the fact that the carriers have committed to deploying it in rural areas where they have traditionally kept those areas a generation or two behind. This is predominantly a USA problem in the wireless space though. Current 4G technology is plenty fast to stream any resolution.
I think he had to for any āsourceā to adopt it. Tidal would never have adopted it if they had to keep track of which format a user supported at the time of the play request. From a streaming perspectiveā¦ itās just PCM. Is there is a way to unfold on the far end? They donāt need to know being as its always the same stream being sent. A new format would have made MQA better but then much harder to adopt.
In a wayā¦ itās one of the little bits of magic Roon solvesā¦ Roon automagically moves source to endpoint regardless of formats (well, those supported) and all just works. Remove Roon and this competing format thing is a real problem. Bob was wise not to add yet another competing format.
It could benefit the streaming providers with egress costs. For consumers not everyone has an unlimited data plan yet nor 5G so itās still relevant for todayās mobile use cases if you want higher audio fidelity on the go.
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Why? Isnāt the point of the MQA core decode to get you from 48/24 to 96/24?
When comparing the bandwidth savings, you must ignore any quality changes introduced by putting the extra data below the noise floor (the first unfold). Whether that actually works without degradation is another story, but if one wants to demonstrate that the bandwidth savings is substantial (or not), adding fidelity questioning at the first step is just a distraction. My gut says 48/24 full of noise does not FLAC well, and FLAC of 96/24 does.
You are right. There are certain problems I just donāt even consider anymore, like format support and device compatibility. The world is not Roon-only.
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