Jump to content
Sign in to follow this  
FredericV

Truncating MQA files to 16 bits and the blue light still shines

Rate this topic

Recommended Posts

1 minute ago, Em2016 said:

Very interesting. I wonder if the same happens with an MQA file that’s supposed to pack in more information, like this 353kHz MQA album:

 

https://shop.klicktrack.com/2l/411252/


The files that I used were sourced from 352.8 Khz (not 353Khz which is not a valid sample rate, but I get your point).


Designer of the 432 EVO music server and Linux specialist

Discoverer of the independent open source sox based mqa playback method with optional one cycle postringing.

Share this post


Link to post
Share on other sites
3 minutes ago, FredericV said:


The files that I used were sourced from 352.8 Khz (not 353Khz which is not a valid sample rate, but I get your point).

 

Eep, apologies for rounding up.

 

Share this post


Link to post
Share on other sites
35 minutes ago, FredericV said:


So why does the MQA blue light still shines?

 

 

Implementation by Mytek: perhaps it does not look at the actual encrypted bitstream but only at some value in the header of the FLAC container which says it is MQA....and turns on the 'blue light'.

 

Stick that header to a non-MQA FLAC file and see what happens......

Share this post


Link to post
Share on other sites
35 minutes ago, FredericV said:

If we play the 24/44.1 MQA files from 2L.no,

 

Here you say it’s a 24/44 MQA file but I linked to an actual 353kHz MQA file/album. I wonder if the same happens, given this file should pack in much more info? 

 

Share this post


Link to post
Share on other sites
5 minutes ago, hsmeets said:

 

Implementation by Mytek: perhaps it does not look at the actual encrypted bitstream but only at some value in the header of the FLAC container which says it is MQA....and turns on the 'blue light'.

 

Stick that header to a non-MQA FLAC file and see what happens......

 

Mytek does not know it's a flac of wav. All it sees is PCM. It's a WAV in this test for the 16 bits truncate test.


Designer of the 432 EVO music server and Linux specialist

Discoverer of the independent open source sox based mqa playback method with optional one cycle postringing.

Share this post


Link to post
Share on other sites
5 minutes ago, Em2016 said:

 

Here you say it’s a 24/44 MQA file but I linked to an actual 353kHz MQA file/album. I wonder if the same happens, given this file should pack in much more info? 

 


For 24/88.2, 24/176.4, 24/352.8, .... source files, after encoding the MQA dIstribution files are always 24/44.1

For 48K multiples it's always 24/48


Designer of the 432 EVO music server and Linux specialist

Discoverer of the independent open source sox based mqa playback method with optional one cycle postringing.

Share this post


Link to post
Share on other sites

Oops, yes it’s a DAC and not a mediastreamer. Well, the MQA signature must then be embedded in more significant bits, so maybe truncate more bits.

Share this post


Link to post
Share on other sites
4 minutes ago, FredericV said:


For 24/88.2, 24/176.4, 24/352.8, .... source files, after encoding the MQA dIstribution files are always 24/44.1

For 48K multiples it's always 24/48

 

Ok, noted.

Share this post


Link to post
Share on other sites
32 minutes ago, mansr said:

This is by design. The MQA identification and authentication data is embedded in bit 8 of a 24-bit PCM stream. Dropping bits 0-7 thus leaves it untouched. The authentication works by computing a Blake2s hash over the top 15 bits (the plain PCM portion) and parts of the control stream in bit 8. This hash is then verified against a cryptographic signature extracted from the control stream. The public key is stored in the decoder. If the signature matches, the blue light goes on. The low 8 bits encoding the high-frequency content are not covered by the authentication.


I wonder if MQA CD is just the 24 bits MQA encode truncated to 16 bits. That would only work for masterings in multiples of 44.1K.
Then they can license the 24/44.1 files to Tidal and as also sell as downloads, where the customer has the illusion it's something higher like 176.4K or 352.8K after MQA decoding.
 


Designer of the 432 EVO music server and Linux specialist

Discoverer of the independent open source sox based mqa playback method with optional one cycle postringing.

Share this post


Link to post
Share on other sites
35 minutes ago, mansr said:

This is by design. The MQA identification and authentication data is embedded in bit 8 of a 24-bit PCM stream. Dropping bits 0-7 thus leaves it untouched. The authentication works by computing a Blake2s hash over the top 15 bits (the plain PCM portion) and parts of the control stream in bit 8. This hash is then verified against a cryptographic signature extracted from the control stream. The public key is stored in the decoder. If the signature matches, the blue light goes on. The low 8 bits encoding the high-frequency content are not covered by the authentication.

But if I understand the original poster correctly, it not only authenticates but somehow is upsampling to 352KHz... How does that work? What is the quality of the signal coming out? Would love to see it. Would also love to see the first unfold of this.


mini+Roon > dCS Rossini DAC + Rossini Master Clock >

Audio Note Kondo Ongaku > Avantgarde Duo Mezzo G2

system pics

Share this post


Link to post
Share on other sites

Perl script released under GPLv2:

http://432evo.be/perl/mqastripper.pl
http://432evo.be/perl/mqastripper.txt

I also intend to add a feature where bits 0..7 are replaced by a repeating ASCII string, to see what that does with authentication.        


Designer of the 432 EVO music server and Linux specialist

Discoverer of the independent open source sox based mqa playback method with optional one cycle postringing.

Share this post


Link to post
Share on other sites

This is all very interesting.   But how can all of this manipulation possibly result in better sound?  I don’t care if it is a $50K dCS or a $499. iFI, none of this processing can be good for music — or humans for that matter.

 

I submit that the primary benefit of most digital systems is convenience and, sadly, if you look at other threads on this site, you will see that library management, storage, connectivity and other issues are still major issues.

 

It all makes me wonder if the much maligned, non audiophile, iPod generation has it right, just put your music on a phone and get some ear buds — burn your Stereophile magazines and forget all this digital pain, life is to short.


In any dispute the intensity of feeling is inversely proportional to the value of the issues at stake ~ Sayre's Law

Share this post


Link to post
Share on other sites
3 hours ago, esldude said:

This is what is a true shame about High end audio in the modern world.  It leaves one thinking simple is a guarantee of poor quality (30 years ago it was the reverse).  That you need not only superb (and obscenely expensive) gear, but a whole trove of add ons just to get this supposedly great gear to function much at all.  

 

It is not true.  It breeds needless worry for what should be fun hobby.  And it makes this hobby needlessly expensive and complex.  A music lover who appreciates quality sound should get a step off the  bottom rung and ignore the rest of this baloney.  Beyond that you are exactly right.  For everyone else the value proposition is much better to just iphone it and roll on. 

 

 

Post of the day award!!!


In any dispute the intensity of feeling is inversely proportional to the value of the issues at stake ~ Sayre's Law

Share this post


Link to post
Share on other sites

The technical basis of MQA rests on two concepts:

 

1. There is very little music information above 50 kHz.

 

2. High-res sounds good because of time domain performance.

 

In Stuart's and Carver's view, almost all of the music data is present within a sample rate of 96 kHz, and information above that is just noise. MQA seeks to maintain the music data, eliminate the bandwidth dedicated to noise, while improving time domain performance.

Share this post


Link to post
Share on other sites
1 minute ago, GUTB said:

The technical basis of MQA rests on two concepts:

 

1. There is very little music information above 50 kHz.

That much I agree with.

 

1 minute ago, GUTB said:

2. High-res sounds good because of time domain performance.

This is patently false.

 

1 minute ago, GUTB said:

In Stuart's and Carver's view, almost all of the music data is present within a sample rate of 96 kHz, and information above that is just noise. MQA seeks to maintain the music data, eliminate the bandwidth dedicated to noise,

All that can be done using standard FLAC.

 

1 minute ago, GUTB said:

while improving time domain performance.

That's bollox.

Share this post


Link to post
Share on other sites
Just now, mansr said:

That much I agree with.

 

This is patently false.

 

All that can be done using standard FLAC.

 

That's bollox.

 

Stuart and Carver made their cases for time domain. Has someone rebutted it?

Share this post


Link to post
Share on other sites
29 minutes ago, GUTB said:

 

Stuart and Carver made their cases for time domain. Has someone rebutted it?

Maybe we should ask Mr. Craven.


To paraphrase Rick James, "sighted listening is a helluva drug".

Share this post


Link to post
Share on other sites
1 hour ago, mansr said:

Show me the maths.

Is this your version of show me the money?


NUC7PJYH/AL --> Berkeley Alpha USB --> Jeff Rowland Aeris --> Jeff Rowland 625 S2 --> Focal Utopia 3 Diablos with 2 x Focal Electra SW 1000 BE subs

 

i7-6700K/Windows 10 Version 1903/HDPLEX 200W/HDPLEX 400W DC-ATX --> EVGA Nu Audio Card --> Focal CMS50's 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...