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Offline sandyk  
#1 Posted : 02 November 2019 04:44:41(UTC)
sandyk


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E.E. John Dyson's Dolby A Software Decoder Project. ("DHNRDS")

Currently, highly experienced E.E. John Dyson is working on a project to preserve for future generations, quite a few famous CD releases from earlier years
where they didn't correctly implement (if at all) the decoding from the Dolby A noise reduction system used at the time.
This made many earlier releases sound shrill and even irritating. John is using mainly ABBA for this as it has by far the most problems .
Even many earlier releases from other albums including The Cars, Carly Simon, The Carpenters, Nat King Cole and Olivia Newton John suffered from these problems too.

John's Software program " DHNRDS" is far more accurate than the original Dolby -A decoders, and is even capable of reducing or eliminating artifacts
caused by the original Dolby-A encoding.

At my request,John posted this release in a smaller forum where I am also a Moderator, and I have John's permission to post it here too.
I have been working closely with John in this area for around 6 months now. This material has also been posted in Audiophile Style Forum, from the original post in the smaller forum

Alex

" Good news -- I have to announce this somewhere because it IS a major breakthrough in the DHNRDS DA decoder.
This is a long background story that no-one wants to hear, but the bottom line, I ended up looking again at the DHNRDS DA decoder for distortion issues.
After chasing down some rabbit holes and revisiting the design goals, I had realized that my original goals were 'bug for bug', but better than DolbyA HW.
I believe that goal was wrong. I changed the 'goal' temporarily -- I believe it is now a permanent change. NOW -- the goal is 'Better than DolbyA HW... period.
I stripped out some of the emulation code that supports some of the DolbyA HW bugs. For example, one of the bugs is that the signal attacks have a limited slew rate
because the effective drive voltage is limited when running in expander mode. I stripped out the 'drive voltage' limitation in the code (of course, an emulation),
and lo-and-behold, the garble that happens on complex/mixed large signals that happens with DolbyA units and also the previous DHNRDS versions is now pretty much GONE.
The previous DHNRDS DA version was pretty good at getting rid of the DolbyA HW decoding fog at low levels, but that doesn't happen nearly as often as the louder mixed chorus
and mixed instruments. With this modification, the DHNRDS DA can now track the signal more accurately than previously and more accurately than the DolbyAHW --
thereby reducing the high level garble.
My initial evaluation of the improvement produces results almost as important as the initial versions that were often better better than DolbyA HW.
There is a very significant improvement in sound quality.
I will check into a few matters regarding forum message distribution/etc, but if it is small enough, I'll provide a repository for examples in the next few days.
If this was not a major improvement -- I would NOT have bothered posting this message. This upcoming change will make a much more significant improvement in decoding results
over previous DHNRDS versiona AND DolbyA versions. I wouldn't be surprised that a lot of material will be heard much more similarly to the original input to the DolbyA/Tape recorder
complex.

Some very difficult material, including ABBA (the recordings that I use for my ACID tests), are sounding very eerie.... Stuff like 'SuperTrouper' actually sounds almost natural?!?!
Bread is really, really, really nice sounding, and the Carpenters recordings are coming out better than I have EVER heard.

Examples will be forthcoming -- next few days. Anyone who has REALLY EVIL DolbyA material that they'd like to resurrect -- I can supply a decoder,
or even do a decoding operation gratis (I am very good about keeping private/unpublished/NDA material private, and happily destroy temporary copies.)
The DHNRDS can make DolbyA material sound less foggy, have better vocal chorus (less rough mixing), lots of other improvements.

John


Gang -- the new version of the DHNRDS (actually, I haven't officially produced a release yet, will do so tomorrow) is still working very well :-).
PLEASE ENJOY, and feel free to criticize (kindly :-)).

I'd suspect that most people reading this already know the context of the DHNRDS DA decoder, basically intended to resurrect older recordings, eliminating the DolbyA HW
as a quality limitation. Note that the DolbyA HW isn't all that bad for mixing down, because the material being mixed tends to have relatively simpler dynamics and signal statistics.
The DolbyA doesn't do too bad for mixing down, but could be improved on. Where the DolbyA really falls down is handling the final mix.
All of the interactions in the individual signals
added together are too much of a challenge for DolbyA HW. (Lets keep in mind, the DolbyA was designed in the middle 1960s, and Ray Dolby was pretty much a magician designing
the DolbyA itself.) The DolbyA design has definite indications of genius in the circuitry -- it is MUCH MUCH more intricate than an initial read of the schematic might suggest!!!

* Most of my decoding is done on the brighter side... It can be toned down, but choosing the correct EQ is tricky as hell!!! Also, the recordings could stand a little better balance --
again I chose a brighter decoding result, but can be tamed.
I unleashed the DHNRDS DA from being 'Bug for Bug' compatible with the DolbyA, and basically changed it to be 'as good as possible'.
The sound might be VERY different than you expect, esp for ABBA. LindaR should seem REALLY good also. Of course, my taste might not be quite right.
My own initial opinion is 'astonishing' sound quality.
Mega Caveat: IS very tricky to undo the EQ that was done to skip the DolbyA decoding step -- I can provide the parameters that I used, and you can try passing the material
through a true DolbyA if you wish -- given the parameters that I provide. I doubt that you would like the sound of the DolbyA in comparsion, but each of us has our own opinions. :-).
Normal professional use of the DHNRDS does NOT need for the EQ correction, but decoding feral DolbyA is a very tricky thing to do!!!
Please be tolerant of me about the Carpenters recordings. You might notice more sibilance than normally desired. I think that part of the issue is that the true DolbyA
cannot track the signal, so it was enhanced to compensate. Since the DHNRDS DA can track ANY audio signal, the boosted sibilance is passed through cleanly.
If mastering the Carpenters material, it might be a good thing to run it through a sibilance processor or maybe change the pre-decoding EQ a little on the most egregious songs.
Usually a little bit of manipulation in the 6kHz range can help, but the pre-decoding EQ is totally vanilla and is intended to be correct, not just to sound good!!!


I have produced some snippets (full recordings on request) of some stuff that has probably not been heard as cleanly for at least 30yrs. So far, there are some 'Linda Ronstadt' recordings,
and some 'ABBA'. Carpenters is coming in another hour or so, and also I plan to produce some Olivia Newton John snippets.
The Linda Ronstadt examples are NOT 'manipulated' after decoding, and I don't plan any manipulation of ONJ or Carpenters either. (More will likely be coming, e.g. Bread --
which REALLY sounds good now.) The ABBA stuff has been slightly manipulated after decoding because their tonal balance is too biased away from the bass range,
so I have added about 1.5dB below 360Hz on ABBA for easier casual listening.
Of course, LindaR and ABBA are done, and I have the correct decoding parameters for Carpenters and running the decode just this second.
I'd suggest checking the repository now (or whenever) and looking again every day or so for new stuff. "



www.dropbox.com/sh/g7bye...V4R5FYZXDFlAz3HNFoa?dl=0



I have attached a link to an original release of one of the Abba tracks from POLCD-242 (Sweden)
This is one of the better versions, compared with most of the Abba Compilation CDs where they used pure Undecoded Dolby A.
It can be played directly using the Dropbox player

Please do not pass these examples on to others. They are meant for personal evaluation use only.

Alex

https://www.dropbox.com/...y%27s%20Brother.wav?dl=0

Edited by user 02 November 2019 05:58:58(UTC)  | Reason: Not specified

Offline sandyk  
#2 Posted : 04 November 2019 00:00:13(UTC)
sandyk


Rank: Moderator

Joined: 14/03/2012(UTC)
Posts: 631
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Location: Sydney

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Was thanked: 24 time(s) in 24 post(s)

I am currently listening to the most recent bug fix by John Dyson with Abba recordings , which is likely to be the final version.
They sound SUPERB when compared with the originally released recordings.

If anybody would like to have a copy for personal evaluation ONLY, please send me a PM for the Download links . There are 23 different tracks in total in .flac format at 16/48K

Kind Regards
Alex
Offline Simon Briggs  
#3 Posted : 04 November 2019 10:08:40(UTC)
Simon Briggs


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Originally Posted by: sandyk Go to Quoted Post

I am currently listening to the most recent bug fix by John Dyson with Abba recordings , which is likely to be the final version.
They sound SUPERB when compared with the originally released recordings.

If anybody would like to have a copy for personal evaluation ONLY, please send me a PM for the Download links . There are 23 different tracks in total in .flac format at 16/48K

Kind Regards
Alex


Hi Alex,

Thanks for this be most interested to listen to these

Simon
Offline Simon Briggs  
#4 Posted : 05 November 2019 09:22:17(UTC)
Simon Briggs


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The snippets I have listened too have been most encouraging, evaluation continues....

Thanks Alex..
Offline sandyk  
#5 Posted : 05 November 2019 20:44:02(UTC)
sandyk


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Originally Posted by: Simon Briggs Go to Quoted Post
The snippets I have listened too have been most encouraging, evaluation continues....

Thanks Alex..


Hi Simon
Thanks for your reply .
Kind Regards
Alex

John Dyson has given me permission to repost the following post in HiFi Critic Forum
John attempts to explain why many historically important musical performances made available to consumers, never sounded as good as they should have and why many people preferred the same releases on Vinyl.


Post by johndyson on yesterday at 12:01am http://music-and-percept...?page=1&scrollTo=586

I created a separate thread because this doesn't apply only to the DHNRDS, but the general state of the old recordings originally created/mixed down in the 1960s
through early 1990's...
First, the original 'Harsh digital sound' complaints didn't come from only one cause, as there were at least three reasons (not in the order of impact):
1) Early state of 'digital audio' technology.
2) Unexpected signal detail that was partially covered up by complex dynamics in vinyl production
3) Different final/production mastering for digital media vs. analog media.
I believe that items 1 and 2 have been well understood all along, and the relative magnitudes of items 1 and 2 have been discussed for 30+yrs.
Item 3 has been underestimated or ignored in the public/consumer arena. This is a real problem, and has varying magnitude depending on the exact difference.
I dont' know enough about the final mastering (I am not speaking of mixing the material, I am writing here about the two track stereo being prepared for distribution),
to know all of the steps, but there are some deviations between the handling of digital vs. analog material.---

This discussion is not solely intended to shill for the DHNRDS -- that is NOT the goal here, but maybe to explain why the 'love' for vinyl and other analog media had
been sparked and even sustained for so long. There are definitely recordings which cannot sound as good as they should, some are simply NOT available in their
natural form. Instead, some material is still mostly available in the 'harsh digital' form unless on vinyl or properly mastered tape.
For an example of the 'natural' Carpenters sound -- refer to the link below -- it must be removed in a few days, but it is here for illustrative purposes.
TRY to find a natural sounding Carpenters distribution... You might have problems doing so -- unless you have vinyl or a VERY VERY special digital copy.
Even the Carpenters 'singles' on HDtracks is NOT DolbyA decoded!!! It does NOT have the natural sound. (I haven't been able to 100% accurately decode the
Carpenters until recently, only possible once I found the correct inverse equalization...)

www.dropbox.com/sh/g7bye...V4R5FYZXDFlAz3HNFoa?dl=0

I have listened to a LOT of CDs made from older recordings, both CDs mastered/produced in the early days of digital, and CDs/digital produced more recently,
and it is extremely clear to me that the differences can be enumerated as below:

1) No DolbyA decoding, substituted by EQ
2) No DolbyA decoding, not substituted by EQ
3) Additional manipulation, incl compression.

In recent years, becoming much more prominent starting in the middle 1990s, and even more egregious in the 2000's and beyond, dynamic range has been deemphasized
as a desirable trait, and loudness seems more important to the distributors. This dynamic range matter is well understood, and even some of the motivations for
decreased dynamic range are understood -- it is the other items that I am writing about here. Actually, this missing step of DolbyA decoding, and the oassociated decrease
in high frequency dynamic range MIGHT have been a contributing factor to the current 'loudness wars' and the consumer toleration for decreased dynamic range!

Here is the scenario that has happened REPEATEDLY in the past:

DolbyA Recording -> EQ -> distribution to consumer

Instead, the following should have happened:

DolbyA Recording -> DolbyA decode -> distribution to consumer

One may ask: Why did this happen? I have no firsthand knowledge, but just existance proof. It has taken some time to collect the information,
but there might be several causes:

1) Material already in digital form, archived by LOC procedures that make NR decoding before archiving an optional step.
2) Insufficient metadata/documentation and/or missing calibration tones making the decoding effort inconvenient.
3) Time/cost of realtime limited for HW DolbyA decoding, much slower & inconvenient than copying digital files directly.

When looking at these items above, and the fact that distribution moves a commodity around, it is not an artistic endeavor from the standpoint of the business people,
I'd suspect that there is sometimes an explicit financial decision to do EQ to attempt to hide the DolbyA encoding instead of the actual decoding operation itself.
EQ can be done digitally fast, while decoding actually takes 1:1 time on recording vs. time to decode.

Mentioning the details of the problem again: when the mastering was done by the distributor, instead of DolbyA decoding, they did an EQ operation like this:
Recording -> EQ -> distribute
instead of
Recording -> DolbyA decode -> distribute...
So, what the remastering does is this:
distribution copy -> inverse EQ -> DolbyA decode -> 'better sound results'
The problem is that the original EQ isn't documented, and also the ongoing problem was that I didn't realize how precise the EQ needed to be...

What is my goal here -- mostly to do what I can do to resurrect the old recordings. These recordings are important to history and will NOT be heard correctly unless
correctly and accurately processed....


John

Edited by user 05 November 2019 21:33:13(UTC)  | Reason: Not specified

Offline kengale  
#6 Posted : 07 November 2019 17:07:24(UTC)
kengale


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Posts: 1,333
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Originally Posted by: sandyk Go to Quoted Post
Originally Posted by: Simon Briggs Go to Quoted Post
The snippets I have listened too have been most encouraging, evaluation continues....

Thanks Alex..


Hi Simon
Thanks for your reply .
Kind Regards
Alex

John Dyson has given me permission to repost the following post in HiFi Critic Forum
John attempts to explain why many historically important musical performances made available to consumers, never sounded as good as they should have and why many people preferred the same releases on Vinyl.


Post by johndyson on yesterday at 12:01am http://music-and-percept...?page=1&scrollTo=586

I created a separate thread because this doesn't apply only to the DHNRDS, but the general state of the old recordings originally created/mixed down in the 1960s
through early 1990's...
First, the original 'Harsh digital sound' complaints didn't come from only one cause, as there were at least three reasons (not in the order of impact):
1) Early state of 'digital audio' technology.
2) Unexpected signal detail that was partially covered up by complex dynamics in vinyl production
3) Different final/production mastering for digital media vs. analog media.
I believe that items 1 and 2 have been well understood all along, and the relative magnitudes of items 1 and 2 have been discussed for 30+yrs.
Item 3 has been underestimated or ignored in the public/consumer arena. This is a real problem, and has varying magnitude depending on the exact difference.
I dont' know enough about the final mastering (I am not speaking of mixing the material, I am writing here about the two track stereo being prepared for distribution),
to know all of the steps, but there are some deviations between the handling of digital vs. analog material.---

This discussion is not solely intended to shill for the DHNRDS -- that is NOT the goal here, but maybe to explain why the 'love' for vinyl and other analog media had
been sparked and even sustained for so long. There are definitely recordings which cannot sound as good as they should, some are simply NOT available in their
natural form. Instead, some material is still mostly available in the 'harsh digital' form unless on vinyl or properly mastered tape.
For an example of the 'natural' Carpenters sound -- refer to the link below -- it must be removed in a few days, but it is here for illustrative purposes.
TRY to find a natural sounding Carpenters distribution... You might have problems doing so -- unless you have vinyl or a VERY VERY special digital copy.
Even the Carpenters 'singles' on HDtracks is NOT DolbyA decoded!!! It does NOT have the natural sound. (I haven't been able to 100% accurately decode the
Carpenters until recently, only possible once I found the correct inverse equalization...)

www.dropbox.com/sh/g7bye...V4R5FYZXDFlAz3HNFoa?dl=0

I have listened to a LOT of CDs made from older recordings, both CDs mastered/produced in the early days of digital, and CDs/digital produced more recently,
and it is extremely clear to me that the differences can be enumerated as below:

1) No DolbyA decoding, substituted by EQ
2) No DolbyA decoding, not substituted by EQ
3) Additional manipulation, incl compression.

In recent years, becoming much more prominent starting in the middle 1990s, and even more egregious in the 2000's and beyond, dynamic range has been deemphasized
as a desirable trait, and loudness seems more important to the distributors. This dynamic range matter is well understood, and even some of the motivations for
decreased dynamic range are understood -- it is the other items that I am writing about here. Actually, this missing step of DolbyA decoding, and the oassociated decrease
in high frequency dynamic range MIGHT have been a contributing factor to the current 'loudness wars' and the consumer toleration for decreased dynamic range!

Here is the scenario that has happened REPEATEDLY in the past:

DolbyA Recording -> EQ -> distribution to consumer

Instead, the following should have happened:

DolbyA Recording -> DolbyA decode -> distribution to consumer

One may ask: Why did this happen? I have no firsthand knowledge, but just existance proof. It has taken some time to collect the information,
but there might be several causes:

1) Material already in digital form, archived by LOC procedures that make NR decoding before archiving an optional step.
2) Insufficient metadata/documentation and/or missing calibration tones making the decoding effort inconvenient.
3) Time/cost of realtime limited for HW DolbyA decoding, much slower & inconvenient than copying digital files directly.

When looking at these items above, and the fact that distribution moves a commodity around, it is not an artistic endeavor from the standpoint of the business people,
I'd suspect that there is sometimes an explicit financial decision to do EQ to attempt to hide the DolbyA encoding instead of the actual decoding operation itself.
EQ can be done digitally fast, while decoding actually takes 1:1 time on recording vs. time to decode.

Mentioning the details of the problem again: when the mastering was done by the distributor, instead of DolbyA decoding, they did an EQ operation like this:
Recording -> EQ -> distribute
instead of
Recording -> DolbyA decode -> distribute...
So, what the remastering does is this:
distribution copy -> inverse EQ -> DolbyA decode -> 'better sound results'
The problem is that the original EQ isn't documented, and also the ongoing problem was that I didn't realize how precise the EQ needed to be...

What is my goal here -- mostly to do what I can do to resurrect the old recordings. These recordings are important to history and will NOT be heard correctly unless
correctly and accurately processed....


John


I'm amazed. Are we saying that a large number of Dolby-A-encoded tape masters are being re-issued digitally by digitising the masters without using Dolby A decoder first (or using digital Dolby-A decoding)? What on earth were the companies thinking of? I'd always presumed that the studios would hold on to their analogue decoders precisely so that they COULD at any time play the recordings correctly decoded.
I've not got much way of checking this on my own stuff - most of these fairly historic recordings I possess as vinyl and I don't have any intention of buying digital versions, though I do have some CD's with quoted copyright dates of around the Dolby/analogue period so may or may not be correctly recorded/decoded.

Edited by user 07 November 2019 17:08:18(UTC)  | Reason: Not specified

Offline sandyk  
#7 Posted : 07 November 2019 21:02:22(UTC)
sandyk


Rank: Moderator

Joined: 14/03/2012(UTC)
Posts: 631
Australia
Location: Sydney

Thanks: 5 times
Was thanked: 24 time(s) in 24 post(s)
Hi Ken
I have heard some of these original versions and they are shrill sounding and harsh. What has become most apparent though, is that the worst offending versions are invariably the compilation albums where they have either made no attempt to decode the Dolby A or have attempted to use EQ in various areas, as their contents usually come from different albums, where they may also have done different EQ on them originally.
Unfortunately, the ones that I linked to for Simon had a little too much EQ at the very low end and lost much of their vibrant sound.
They arrived in my inbox while I was drafting a reply to Simon, and hadn't had a chance to listen to them.
John wondered about this himself, just before I pointed this out to him. The version of the Abba files from just one day earlier sounded much better in almost all respects, except track 23 which had a grating type sound to it that John had missed . This resulted in the rushed version that Simon heard, as John was also tied up in another project.
John will rectify this setting when he returns home in a couple of days time.

Kind Regards
Alex

Edited by user 07 November 2019 21:05:12(UTC)  | Reason: Not specified

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