Compression restoration-how does this work?

[Spdmn256]

There is a function called M-DAX on my Marantz AVR (restorer on Denon, music optimizer on Onkyo). Is this an algorithm based on the original compression routines, providing content maybe the way an upmix provides surround from 2ch or something else?* Would be interested if anyone knows how this works or what it really does?

*@lovinthehd hope you don’t mind I borrowed a little of your wording to create this new post per your suggestion, thank you.

 

[TheWarrior]

I'll be interested to see if anyone knows more....

But to me, this reads like typical Marketing Propaganda!

'Better sound through research"

 

[Steve81]

Based on the below, guessing it probably just provides a bit of EQ:

M-DAX

Compressed audio formats such as MP3, WMA (Windows Media Audio) and MPEG-4 AAC reduce the amount of data by eliminating signal components that are hard for the human ear to hear. The “M-DAX” function generates the signals eliminated upon compression, restoring the sound to conditions near those of the original sound before compression. It also restores the original bass characteristics for a rich and expanded tonal range.
Mode

High:
Optimized mode for compressed sources with very weak highs (64 kbps and under).
Medium:
Apply suitable bass and treble boost for all compressed sources (96 kbps and under).
Low:
Optimized mode for compressed sources with normal highs (96 kbps and over).
Off:
Do not use “M-DAX”.

 

[lovinthehd]

M Code added to the other thread with this:

Somewhere in my archives I have the TI white paper on the MP3 Restore algorithm...
I recall..
that it basically worked by taking the lower frequencies and then generating higher frequency harmonics. On a scope U could see the improvement but the audible effect was very subtle..

Just my $0.02..

• 
  

 

[Kvn_Walker]

M Code added to the other thread with this:

Somewhere in my archives I have the TI white paper on the MP3 Restore algorithm...
I recall..
that it basically worked by taking the lower frequencies and then generating higher frequency harmonics. On a scope U could see the improvement but the audible effect was very subtle..

Just my $0.02..

• https://forums.audioholics.com/forums/rating/list?content_type=post&content_id=1291294&rating_type_category_id=3

Kind of like when I listen to CD vs 320k MP3. "I know it's lossy" doesn't mean jack if I can't hear the difference.

Back to the point though, Creative has had a function called "crystalizer" available in its sound cards for a long while:
https://www.soundblaster.com/technology/sbx-pro-studio?crystalizer

 

[BoredSysAdmin]

I've seen some truly remarkable examples of newest AI systems and algorithms trained on the certain datasets like photographs could actually replace the missing data with very real looking substitute. One such examples is Google's AI capable of removing most watermarks from the photos. Something similar to it could theoretically be applied to system able to recover sound from lossy recordings.
That said, I want to assure you that similar functionality in modern consumer electronics is nowhere near as good as AI network trained for the specific task.

 

[Kvn_Walker]

I've seen some truly remarkable examples of newest AI systems and algorithms trained on the certain datasets like photographs could actually replace the missing data with very real looking substitute. One such examples is Google's AI capable of removing most watermarks from the photos. Something similar to it could theoretically be applied to system able to recover sound from lossy recordings.
That said, I want to assure you that similar functionality in modern consumer electronics is nowhere near as good as AI network trained for the specific task.

I wonder how far that could get in today's world of hair-trigger copyright lawsuits. A good AI would recognize the song (possibly even connect to an online database or neural net), estimate the amount of loss, then restore the bits to original fidelity. But record companies would of course want royalties for every such use, rendering it DOA.

Even without the financial aspect, how much should one invest when it's the same cost (whether one uses legal means or file sharing) to obtain the lossless version of a file versus the compressed version? True restoration would be a great proof-of-concept project though.

 

[BoredSysAdmin]

I wonder how far that could get in today's world of hair-trigger copyright lawsuits. A good AI would recognize the song (possibly even connect to an online database or neural net),estimate the amount of loss, then restore the bits to original fidelity. But record companies would of course want royalties for every such use, rendering it DOA.

Even without the financial aspect, how much should one invest when it's the same cost (whether one uses legal means or file sharing) to obtain the lossless version of a file versus the compressed version? True restoration would be a great proof-of-concept project though.

I don't see this as copyright issue as you already should have bought the right to "own" (limited license actually) the compressed version, but this becomes a big thing, I could see some legal issue as RIAA greed has no bounds.

 

[M Code]

Kind of like when I listen to CD vs 320k MP3. "I know it's lossy" doesn't mean jack if I can't hear the difference.

Back to the point though, Creative has had a function called "crystalizer" available in its sound cards for a long while:
https://www.soundblaster.com/technology/sbx-pro-studio?crystalizer

Each brand had their own marketing spin for this feature...
If the base product used a TI audio DSP chip, they had access for this @ royalty free... Also other audio DSP makers including ADI, Cirrus Logic, Crystal, Fujitsu also had a similar feature..

Just my $0.02...

 

[davidscott]

Didn't DBX try to do this back in the day?

 

[M Code]

Didn't DBX try to do this back in the day?

Yup...
Some years back, DBX had a harmonic bass expander...
Took a LF harmonic and then created additional bass harmonics..
I think they got some traction with it in the pro audio products but not consumer..

Just my $0.02...

 

[lovinthehd]

Didn't DBX try to do this back in the day?

I still have my DBX 1BX Dynamic Range Expander! Might pull that out and play with it again now that you mention it....

 

[davidscott]

I still have my DBX 1BX Dynamic Range Expander! Might pull that out and play with it again now that you mention it....

Glad I could help.