The mastering issue, nerve grinding

[gmgraves]

On 7/30/2019 at 6:56 AM, John Dyson said:

Dear Hornet's nest:

 

The left over DolbyA imprint just struck again yesterday:  I just ran into the 6th or more (not 100% sure) premium download album that didn't sound quite right.  These are apparently still 'noise reduction' encoded.

 

Note before reading further:  I am not criticising anyone in particular, and definitely not codemning the people doing the mastering/remastering/etc, a lot of the time there are documentation problems and other complications that make their jobs a little tricky -- I am only commenting on the state of affairs, and the problem of not-so-good material reaching the consumer. I generally do not include proper NR decoding as a part of mastering, because it *should* be a part of the normal process to prepare for the consumer -- mastering should be considered the extra steps done to make the recording better/cleaner/etc for the consumer. (Mastering might include massaging the material to fit better on vinyl, for example.)

 

This observation has happened on numerous pieces premium 'material', 192/24 or 96/24...   I have 3/Simon&Garfunkel 192/24, Roberta Flack 192/24, Carpenters 96/24, PaulMc 96/24 and maybe a few others -- this is enough of a set of examples.  It seems likely that the 'quality' problem is still a left-over DolbyA-like imprint on these recordings.  The most ugly thing isn't the HF compression per-se, but the thin (compressed depth) stereo space left on these recordings.   *This quality experience/difference is difficult to describe, and is best experienced.  Suffice to say, I am NO golden ears, but can clearly hear the difference/improvement of proper handling of recordings.

 

These more egregious examples are mostly from well-known pay-for-download sites ( the download sites are not especially at fault -- they are selling what is available to them.  The distribution
is the problem.)  The problem doesn't come from any one seller -- I have some old CDs from eons ago also with the left-over imprint.  Of course, we don't expect the old CDs to be perfect, but it would be nice.  However, with proper re-EQ, and decoding, many CDs can be incredibly improved.

 

This last Roberta Flack example was a bit of a 'oh, my' kind of moment.  Luckily, I did borrow a song from a friend (I already had the normal CD) so I could determine if I wanted the 'pristine' copy.  I guess I can say -- no bother about getting the 'premium' album, that is unless I need to hear the above 20kHz noise/other artifacts on the album.  Unfortunately there appears also a DolbyA encoding imprint on the 'premium' album, but seems to have been further damaged by some compression.  So, this 'premium' album is even less useful to me than the old CD -- at least, I can clean-up the CD.

 

Why do I notice this FRUSTRATING problem?  I am in a almost unique position that I can actually diagnose the problem, and can resolve it - not so much at the consumer level, however.  The software to 'detect'/'correct' the problem is not a simple thing to do, and is definitely not a weekend project.  Using the decoding software is NOT for the consumer either -- we need to advocate for more complete digital preparation before we are sent the digital copies.  So, after these 30yrs of digital distributions, I am finding that many of them from over the years are 'just not right'.  Very often, the material appears to be DolbyA encoded.  Recordings are STILL being distributed not 'quite right' even nowadays.

 

With all of the discussion over the years about mp3, opus, 16bit PCM vs 24bit PCM, 192/96 vs 44.1k, etc... to me, knowing what I have learned in the last 3-4yrs, it appears that they are all diversions, because only the slower lossy compression are more important than the 'damage' from non-NR-decoded material reaching the consumer.  (choice between properly mastered 192kmp3 vs. undecoded 192/24, I'll take the mp3 quality anyday.)  I am NOT advocating for mp3 though -- just that the un decoded material sounds worse.

 

I almost blew a 'gasket' with this last album (Roberta Flack, 2012 remaster.)  When purchasing/downloading a 'premium' album, I'd expect that the material wasproperly prepared for the consumer -- but it seems like a lot of material is just not properly handled.  I do have some premium albums (Nat King Cole, for example) which also APPEAR to also have the residual DolbyA imprint, but cannot prove it, even for myself.

 

Given the fact about MQA causing such an uproar (In my opinion ONLY, I still believe that the worst thing about MQA is the obfuscation/complication and possible DRM), I wonder why this missing-mastering-step travesty hasn't caused a riot!?!?!? :-).  Is the thin stereo space, compressed high end material actually good enough?  If that is good enough, then why worry about needing more quality than mp3 at 128k? (rhetorical.)

 

PS: I am only pushing for the distribution chain to do the right thing and properly master the material -- no need to get attention by hypercompressing conventional releases, just do the basic
preparation correctly!!!   Every user cannot practically do their own mastering (or re-mastering), it is the job of the distributors with the actual master tape copies to finish the job!!!

 

John

 

I have used both Dolby-A and DBX  noise “companding” systems and found that as long as one used a 400 Hz “calibration” tone at the head and tail of every recording, and made sure that the tones match “exactly” on playback, that aside from a tiny bit of insertion distortion (which without a direct A/B to the source through headphones, I would defy anyone to notice) that Dolby-A was pretty benign. DBX, OTOH, could be heard to “pump” and noise modulate the signal no matter how carefully levels were matched.

[gmgraves]

5 hours ago, John Dyson said:

As I have written -- the DolbyA decoding distortion is stealthy.  Unless one does a direct A/B comparison on intense material -- most people won't hear it.  DBX does NOT have the same characteristics of DolbyA when it comes to the distortion.  After learning what to listen for -- the problem becomes apparent.  I have found that the 363 decoding is better than an old cat22 in a 360 chassis for some reason -- but the modulation distortion (again -- it is a lack of clarity) exists on both versions.

 

* EDIT -- most of the DolbyA distortion is on the DECODE side, because of the delays and structure of the feedback loop for decoding.  The feedback loop for the decoding on the surface seems correct, and in an ideal world with zero delays -- it could work.  However, the DolbyA units work in the real world, and the delays in the additional layer of feedback create lots of opportunity for imprecision.  In this case, the imprecision is audible.  The DHRNDS does NOT have this flaw.

 

I can show multiple POP examples of DolbyA 'distortion (that is, material which has been publically available), unfortunately, the best controlled cases where there is only 1 pass of DolbyA are on material that is non-public (master tape material.)  I can provide NUMEROUS examples as desired, where I can decode leaked DolbyA vs. a decoded DolbyA copy -- the DHNRDS blows away the commercial DolbyA decoded copy for clarity in places like vocal chorus, and other complex mixes of material.  (Too complex, there is an improvement -- like on 'The Cars' stuff, but not as obvious as vocal chorus.)   On the Cars stuff, you can actually hear the intermod from synthesized material on DolbyA deocded versions, while pristine on the DHNRDS version -- again, ALL PUBLIC MATERIAL (of course, still under copyright, but I can do snippets.)

What does the distortion sound like?   Don't listen for the typical grinding kind of distortion -- even though in the extreme, DolbyA can produce it.   Listen for something that sounds like tape compression.  It is NOT a left over compression though -- even though it does sound like compression IN A WAY.   The best way to explain:  listen to a clean vocal chorus before encoding.   Then, go through an encode/decode cycle -- notice that the 'clean' vocal chorus is no longer clean, but the voices loose their individual nature.  The result of vocal chorus in the higher registers is a 'blob'.   One reason why I use ABBA a lot in testing is that they trigger the problem in most extreme ways.  However, I do have 1st generation encoded DolbyA where an A/B comparison even shows it in a natural recording in a large area setting.

 

What does DolbyA do on other, less intense material?  Generally it isn't intrusive, but there is a loss in detail -- much much much worse than anything that might happen by rate conversion down to 44.1k/16 and frankly, worse than mp3 at 192/256k.  (The loss in time resolution from mp3 doesn't have nearly the negative effect of the conversion of a vocal chorus into a blob.)

 

Where is DolbyA somewhat transparent?  Single instruments, single vocals.  Any time that there aren't multiple complex sources, then DolbyA isn't soo bad.   It is really great for first pass of mixing down material (simple components.)

 

The DHNRDS reduces this modulation distortion very significantly (I cannot say how much, but I'd suspect it is close to 1/10th as much), and makes the results more clean/clear than the alternative.  DHNRDS can make ABBA (as the extreme example) sound MUCH more clear/clean, less 'blaring' in the sound because of more distinct mixed vocals.  However, Olivia is as clean/clear as she has been before DolbyA encoding, and the IMD from 'The Cars' synthesizers is much diminished.

 

Examples available upon request.

 

John

 

 

 

Agreed.

[gmgraves]

On 8/4/2019 at 3:55 AM, John Dyson said:

As I have written -- the DolbyA decoding distortion is stealthy.  Unless one does a direct A/B comparison on intense material -- most people won't hear it.  DBX does NOT have the same characteristics of DolbyA when it comes to the distortion.  After learning what to listen for -- the problem becomes apparent.  I have found that the 363 decoding is better than an old cat22 in a 360 chassis for some reason -- but the modulation distortion (again -- it is a lack of clarity) exists on both versions.

 

* EDIT -- most of the DolbyA distortion is on the DECODE side, because of the delays and structure of the feedback loop for decoding.  The feedback loop for the decoding on the surface seems correct, and in an ideal world with zero delays -- it could work.  However, the DolbyA units work in the real world, and the delays in the additional layer of feedback create lots of opportunity for imprecision.  In this case, the imprecision is audible.  The DHRNDS does NOT have this flaw.

 

I can show multiple POP examples of DolbyA 'distortion (that is, material which has been publically available), unfortunately, the best controlled cases where there is only 1 pass of DolbyA are on material that is non-public (master tape material.)  I can provide NUMEROUS examples as desired, where I can decode leaked DolbyA vs. a decoded DolbyA copy -- the DHNRDS blows away the commercial DolbyA decoded copy for clarity in places like vocal chorus, and other complex mixes of material.  (Too complex, there is an improvement -- like on 'The Cars' stuff, but not as obvious as vocal chorus.)   On the Cars stuff, you can actually hear the intermod from synthesized material on DolbyA deocded versions, while pristine on the DHNRDS version -- again, ALL PUBLIC MATERIAL (of course, still under copyright, but I can do snippets.)

What does the distortion sound like?   Don't listen for the typical grinding kind of distortion -- even though in the extreme, DolbyA can produce it.   Listen for something that sounds like tape compression.  It is NOT a left over compression though -- even though it does sound like compression IN A WAY.   The best way to explain:  listen to a clean vocal chorus before encoding.   Then, go through an encode/decode cycle -- notice that the 'clean' vocal chorus is no longer clean, but the voices loose their individual nature.  The result of vocal chorus in the higher registers is a 'blob'.   One reason why I use ABBA a lot in testing is that they trigger the problem in most extreme ways.  However, I do have 1st generation encoded DolbyA where an A/B comparison even shows it in a natural recording in a large area setting.

 

What does DolbyA do on other, less intense material?  Generally it isn't intrusive, but there is a loss in detail -- much much much worse than anything that might happen by rate conversion down to 44.1k/16 and frankly, worse than mp3 at 192/256k.  (The loss in time resolution from mp3 doesn't have nearly the negative effect of the conversion of a vocal chorus into a blob.)

 

Where is DolbyA somewhat transparent?  Single instruments, single vocals.  Any time that there aren't multiple complex sources, then DolbyA isn't soo bad.   It is really great for first pass of mixing down material (simple components.)

 

The DHNRDS reduces this modulation distortion very significantly (I cannot say how much, but I'd suspect it is close to 1/10th as much), and makes the results more clean/clear than the alternative.  DHNRDS can make ABBA (as the extreme example) sound MUCH more clear/clean, less 'blaring' in the sound because of more distinct mixed vocals.  However, Olivia is as clean/clear as she has been before DolbyA encoding, and the IMD from 'The Cars' synthesizers is much diminished.

 

Examples available upon request.

 

John

 

 

 

Well John, I'll certainly take your word for it. I don't listen to pop recordings and certainly have never recorded any pop material. I have recorded various symphony orchestras, classical wind ensembles, and jazz performances by such luminaries as Dizzy Gillespie, Aaron Copland (conducting), Stepan Grappelli, Phillipe Entremont, Nathan Milstein, etc. I have used Dolby A and tried DBX (didn't like the sound at all). In my early forays into recording the San Jose (CA) Symphony, I used Dolby B, which was pretty benign (the big two-metered, round-trip TASCAM unit - forget the model number, it's been 40 years). But once I bought my (used) Dolby-A setup, I never looked back until I went DAT in the early 90's.