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CD Availability Nearing It's End And The Consequences


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27 minutes ago, John Dyson said:

I don't know if you have read the results of my research - the original 'digital' CD sound was a heinous pattern of mismastering that I call 'FeralA'.  It is an EQed DolbyA compression (without the decoding expansion.)  The result of that kind of twisted mastering is almost plausible, and ONCE IN A WHILE does sound good, but it is not the natrual sound of decoded DolbyA.   This scourge has been prevalent since the beginning of CD, and still persists.   Take a look at the comments about FeralA and decoded DolbyA.  The decoding technology for digital releases is not 100% perfected yet, but is getting VERY VERY close.  (This is NOT commercial snake-oil, but is quite the opposite.)

 

John

 

 

May I politely ask you to summarise:

1. How I can know whether a given rip has DolbyA compression without the decoding expansion; and,

2. In such cases whether it is possible to correct the matter without advanced technical knowledge or expertise - you have developed something?

 

Thank you

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20 hours ago, John Dyson said:

I know this is somewhat off topic, but might be of interest to those who aren't into my 'fringe' interests :-).  Further discussion might best be private or refer to my 'FeralA' commentary in the 'General' area of the forum.  Most of my communications in AS, but also I pop up in other forums from time to time -- but I 'live' here most of the time.   Below is a general & rambling discussion about FeralA and a working solution for it:

====================================================================

 

There has been an experimental decoder of such recordings, and it is moving from 'experimental' to being 'usable' for motivated indvidiuals.  It is NOT commercial, and it is NOT 'snake-oil', but fairly sophsticated DSP software that runs on Windows and/or Linux.

 

1) The 'sound' of the compression can be subtle, and I am not 100% accurate detecting it, even with my long experience working with the decoding methods, but here are some hints:  1) a 'swishy' high end, high hats/cymbals having a rather strong sense of HF compression/too soft.  2) A woody lower midrange, almost like a boost in the 500-1kHz freq range.  It is almost repulsive when not use to it, and encourages turning down the level.  3) Hiss...  Older recordings REALLY needed DolbyA for NOISE REDUCTION, and without full decoding, tends to push the hiss up on older stuff.  4) On a spectogram, you can sometimes see a noise band that gets stronger above about 12kHz -- more than what tape noise would by itself.  5) Distorted stereo image, I notice a 'hole' in the image between 90deg and 45deg (0deg being straight forward, 90deg being left or right.)  6) Strange bass sound.

The compression is 10dB below about 100Hz, 10dB from 3k to 9kHz, 15dB from 9kHz to 20+kHz, and there is active compression at lower levels in the 80-3kHz range, where it is pinned at no compression down to -20dB or so in the midrange.  DolbyA compression is NOT active much above -10dB, so doens't give the 'ducking' quite like a normal compressor might.

 

(NOT ALL SIGNAL MODIFICATIONS ARE MANIFEST STRONGLY -- but the recordings do have those characteristics.)  'FeralA' is a 'stealthy' form of damage esp if one is accomodated to it!!!

 

2)  I have been working on a true, high quality DolbyA compatible decoder which is essentially complete and incredibly accurate/smooth/clean.  'Correcting' or 'decoding' these mismastered recordings requires a corrective EQ back to raw DolbyA, and then do a proper DolbyA decoding.

 

The FeralA  'decoding' software combination is just starting to be plausibly full quality, even though the results had been significantly improving the FeralA sound for several months.  Perhaps the best description is that the decoding results have gone from 'better than original FeralA material', to 'accurate, near master-tape'.

 

The decoding software for the 'FeralA' recordings is free-to-use, but is unfortunately a Windows (or Linux) command line program.   It takes CD .wav file input and creates an 88.2k/FP .wav file output (can also create 24 bit unsigned .wav file also.)   The FeralA decoding software is NOT commercial and money does not change hands for use as the consumer recording converter.

 

So -- the internal operations in the software to correct the recordings is:

From CD ->  corrective EQ -> DolbyA decode -> Ideally, hopefully, more clean sounding recording.

 

================================

As a base, there is a DolbyA decoder, which ALONE  is NOT intended for consumers.   However, I have added some EQ which does the corrective EQ so that the DolbyA decoding mechanism can finish the correction.   When running the professional DolbyA decoder in the 'FeralA' mode as I call it, then it becomes a piece of software that is free to use.

================================

 

The 'FeralA' decoding software is still experimental, but is getting VERY CLOSE to fully working.  Originally, it was a 'science project' to use it, because the decoding required EXTERNAL EQ and using the DolbyA decoder separately.  Now, it is all built in, and I offer the software for free use in 'FeralA' mode.

 

When the '--fa' command line switch is used, it is NOT commercial software and is intended for anyone to use responsibly.   Even though there might be commercial software in the future, the FA decoder that I wrote is NOT commercial and there is zero motive for any direct profit.  It is a learning tool and a technology platform where a plug-in developer in the future might be motivated to develop a 'FeralA' decoder and/or high quality/complete DolbyA compatible decoder.  (It is higher quality than the original DolbyA HW, not because of 'precision', but instead it is improved algorithms.)

 

So -- that is the jist of it...  If anyone needs a DolbyA decoder also (effectively a real product, paradoxically a part of the non-commercial FeralA decoder), the DHNRDS DA mode can produce almost astonishingly clean and beautiful results -- it must be VERY VERY good at decoding DolbyA, because the FeralA decoding is necessarily working with damaged recordings, and the DolbyA decoder must be very tolerant and able to ferret out the distortions that would otherwise be created...

 

John

 

 

This is my first appreciation of your work and, so, please forgive me if I've not got on track.

 

May I address the main idea as I see it. The remedy you describe does not seem to be calibrated. It is an algorithm or process which is applied to recordings which are contaminated. Diserning whether a recording has been contaminated is not always straightforward - even for accustomed ears such as yours. Indeed, the tells you list 1) thru 6) convey the possibility that contamination is a matter of degree rather than category. Whether this is true seems vital. 

 

The simple/best scenario would be the identification of recordings contaminated or not contaminated. I wonder whether records exist even assuming the publishers mightn't want to confess. Otherwise we punters have to decide - and will we agree. The database would be simple - yes or no to a given recording. I feel I have seen the the same barcode used for different masterings of the same Album, so I'm not sure how that would work.

 

The loudness wars database as I read it is more sophisticated in that different recordings are affected by degree - both quantitavely and qualitatively. If the same applies here then the application of your process-remedy will have to be a great deal more sophisticated.

 

Again - apologies if I have misunderstood. I guess I am just interested in the potential for improvement of the valued medium under discussion in this thread.

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1 hour ago, John Dyson said:

I think that the facts are right, but might require rereading from time to time 🙂

 

Thank you for these notes. I am printing them off for reading carefully later.

 

1 hour ago, John Dyson said:

Actually, I grab every version of everything that I like (which I can afford it.)   Perhaps some percentage of the time, I find a good version, but so much material is fatally damaged, most useful for listening in moving car.

 

I have many versions of some recordings which are on my computer as CD rips via EAC. Many = especially, say, Elvis tracks. Whether Elvis or not, the general rule is Quieter = Better on the main system. I presume this is related to extended DR. But the Quieter rule doesn't always hold. e.g. I have a quieter ZZ Top 'Legs' that doesn't sound as good as the louder one. I couldn't say why. Some of the Elvis rips are blatantly corrupt - Loudness. Distortion. Echo. Pitch. Even warble. The variation isn't so obvious with less frequent music. I presume that there aren't electronic "tells" in bad files such that an electronic sweep might id them. We have to use our ears. Given that "The best ideal IS to find material which is not feralA -- PERIOD.", have you created any kind of database yet? This would be useful not just for sanitising existing [feralA-bad] rips, but for seeking out good new or replacement music on CD.

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