DolbyA decoding feedback -- 'feral' examples (yes/no)

[Samuel T Cogley]

7 minutes ago, phosphorein said:

BTW John, I had a listen to “The Logical Song;” what an eye-opener! You’ve done a marvelous job with your decoder.

 

 

Based on this post, I fetched the demo files.  I guess I didn't realize that "proper" decoding seems to restore some dynamic range (it certainly looks that way on the waveform). This is a superb example!

[Samuel T Cogley]

Apologies if this has been discussed and I missed it.

 

With all the boutique, "audiophile" remasters that have been produced since the '90s on labels such as DCC, MFSL, and Audio Fidelity (there are others, these are ones that I personally own and am most familiar with), I'm now really starting to wonder if we were "sold a bill of goods" with regard to the alleged White Glove treatment this remasters received.  If the Dolby A decoding was not applied (and it seems in many cases it was NOT), can we really say the remaster was even competent, let alone, "audiophile quality"?

 

Perhaps @John Dyson can either elaborate on his understanding of Dolby A decoding (or lack of) in those "boutique" settings, or direct me to a post/thread where it's discussed.

 

EDIT: Additionally, since Dolby is an ongoing concern, don't they bear the bulk of the culpability for the lack of "correct" Dolby A decoding in the field?

 

Thanks

 

 

[Samuel T Cogley]

51 minutes ago, John Dyson said:

About the culpability -- responsibility is NOT with the Dolby company, the cupability is with the distributors of the recordings.  The tapes (or even digital copies) of the recordings are often kept in a DolbyA encoded state.  When producing the vinyl or CD, there should be a DolbyA decoding step.  Decoding the material is a choice of the distributor.  I cannot even blame the remastering engineers like Hoffman, because the traditional process would be to deliver the tape (or digital copy) in DolbyA form. It is the distributor who doesn't prepare the tape (or recording) for distribution.

 

The Library of Congress proceedures for archiving old recordings does NOT mandate NR decoding the material.  It is an *optional* step.  The intent is that the decoding should be done immediately before further processing or creationing the version for delivery to the customer.  This means that a lot of digital archives are in DolbyA form.  Frustrating to the production process -- the DolbyA HW only runs in realtime, much slower than a digital file copy.  The DHNRDS DA could solve that problem if ever added to the process,  but I am definitley not expecting that to happen.

 

Thank you John for all that!!!

 

For some reason, I was under the impression that lack of Dolby A decoding was due to lack of hardware decoder availability.  I was thinking that the boutique houses didn't want to purchase the hardware shown at the 2:00 mark on this video (just an example).

 

EDIT: If the hardware isn't available anymore, isn't that Dolby's fault?

 

Using that video as an example workflow, the decoding is part of the digital capture process (but in the analog domain).  I think I hear you saying that capturing un-decoded and then applying the decoding in the digital domain produces better results.  Does Dolby make such a digital decoder?  I'm thinking the answer is no, based on all your work here.

[Samuel T Cogley]

On 12/9/2019 at 4:49 AM, John Dyson said:

During some recent decoding attempts, I decided to make a change to the DHNRDS -- and the results are frightening and astounding both.

Back in the olden days, when DolbyA was used for noise reduction instead of a transport/obfuscation and sound effects mechanism, recording engineers with acute hearing would often complain that DolbyA has a 'fog', that the music ends up sounding less detailed.

 

Spurred on by circumstance and my project partner's idea, I taught the DHNRDS DA to ALMOST look back in time, and to undo some of the distortion created by the ENCODING process.  Not only is the decoding distortion mostly avoided & cancelled, the encoding distortion is now at least partially cancelled.

 

This code is almost a time machine -- I can hear the suppression of modulation distortion when compared with the original DolbyA -- not just with other decodes!!!  The suppressoin cannot be complete, but is very beneficial.

 

I have only decoded a few albums so far, other than some snippets.  When I make more progress in decoding, and having material other than ABBA and Supertramp, I'll probably make some extra-long snippets available.  These results are worth pushing things a little bit.

 

The decoder has turned into a 'time machine'.  Luckily it now knows enough about the expected state of the encoding device to undo some of the original damage to the signal!!!   This benefit should extend to ALL feral material, eliminating any disadvantage to decoding.

 

John

 

 

John, I know others have said this, but I just want to say again that I really, really appreciate your efforts with DolbyA.  We don't deserve you.  👍

[Samuel T Cogley]

Hi @John Dyson

 

I listened to both a few times.  For my listening tests, I raised the level of the "decoded" file by 2.5dB to match the other.

 

I've always looked at 1985 as the year that digital production in the studio eclipsed analog production.  I rarely purchase used vinyl made after 1984 for that reason.  It's likely digitally sourced with under-performing DACs feeding the cutting lathe (or making the tape that feeds the lathe).

 

I see what you mean about the instruments being much more distinct in the decoded version.  There is a synthesizer line in that song I was never fully aware of until today 👍

 

Just curious, how do you determine provenance of a recording (e.g., analog vs. digital production)?  Is it just by listening?