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Everything you never wanted to know about PCM

I recently stumbled upon this bulky article:

http://www.soundfountain.com/amb/cd25years.html

It's incredible how the author manages to intermingle interesting historical information with some gross misreprensentations of the technical aspects of digital audio. Just one example of many:

Quote
16 Bits
The 6 dB per dynamic step does not promote refinement.
A sound that is not at the exact measuring level, will be given the value of the nearest level. ... In other words, if no interpolation would take place, a sound of 2.9 dB above -6 dB would be attributed the value of - 6 dB. A sound of 2.9 dB below 0 dB would be attributed to 0 dB. That is why people, especially in the beginning of the CD era, would say: "It is a violin, but not exactly a violin." Every pianist knows that a digital recording of a piano has less "depth" than an analog recording can have. In other words: the deep sound of the singing of the strings is less.


Of course to the layman the artice will the give the impression of an competent, in-depth technical discussion. So I guess most people would easily be persuated to believe that CDs are inferior Vinyl after reading an article like this.

Everything you never wanted to know about PCM

Reply #1
Instead of mocking him, why don't you just email the guy and explain his misconceptions.  He obviously got in a little over his head, but he seems generally interested in having an accurate site so its worth a shot.  He might listen.

Everything you never wanted to know about PCM

Reply #2
Of course to the layman the artice will the give the impression of an competent, in-depth technical discussion. So I guess most people would easily be persuated to believe that CDs are inferior Vinyl after reading an article like this.
It is good that you mention this site - you know, I fell for it! I actually fell for it! Especially for the example you quoted, not realizing that this would be for - what? - a 4 bit system?


Instead of mocking him, why don't you just email the guy and explain his misconceptions.  He obviously got in a little over his head, but he seems generally interested in having an accurate site so its worth a shot.  He might listen.
He might - he might not. I opt for the latter. He makes it pretty clear that in his view analogue is superior. Just read comments like this "analogue has infinite resolution".
marlene-d.blogspot.com


Everything you never wanted to know about PCM

Reply #4
Oddly enough- if you read the entire piece, he is a champion of the digital format rather than a proponent for analog. He is just pointing out the rather well known weaknesses of the 16 bit 44.1 khz CD format. I have had the luck to be a child of analog, and heard what a well done LP can sound like. As the article states- only a few of us have really heard a well done LP on a system set up to play it. I felt there was to be no digital heaven, as I had been to the analog one first. Luckily for us audio nutcases the DVD has leveled that playing field a bit- like 24 actually. Not to say that 24 bit audio is the end all to analog done well, but it does sound one heck of a lot better than 16 bits could ever hope to. The author also is quick to point out that 32 and 64 bit audio is possible NOW if we as consumers would demand it. Which is why I am here- looking for any information on using the DVD format as a easy way to play 24 bit 96 khz formatted audio. Not talking DVD-Audio format- I want to be able to pop a disc into any DVD-Video player on the market, and more specifically the old Sony 200 disc player I use daily as my cd\dvd player. So here's the question of the day: Anyone here use DVD authoring software that has the abilty to make a .ISO (.UDF) file with a still image for the video and audio tracks at 24 bit 96 khz? I tried the trial copy of HD-Audio Solo Ultra, and all I got were bad .ISO files with errors in it. So I am off to read further but had to respond to this as it was the first thread to come up. Dennis

Everything you never wanted to know about PCM

Reply #5
Hi and welcome.  Please be sure to go over those rules to which you agreed upon registering, namely #5 and #8.  Your post breaks #5 and is borderline #8.

We've been through the vinyl vs CDDA a gazillion times before but the fact remains that CDDA as a distribution format is more than capable of doing anything that vinyl can do except reproduce frequencies above ~22kHz, you know, the ones you cannot hear?
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?


Everything you never wanted to know about PCM

Reply #7
Quote
In other words, if no interpolation would take place, a sound of 2.9 dB above -6 dB would be attributed the value of - 6 dB. A sound of 2.9 dB below 0 dB would be attributed to 0 dB.


He is just pointing out the rather well known weaknesses of the 16 bit 44.1 khz CD format.


No. His calculations are wrong.
A 0 dB sound is coded with a peak-to-peak amplitude of 65535 digital steps.
A sound of -2.9 dB is 10^(-2.9/20) = 0.71614341 smaller.
It is then coded with a peak to peak amplitude of 65535*0.71614341 = 46932.46 steps. This is rounded to 46932 steps because of the 16 bits limitation.

In decibels, this is 20log(46932/65535) = -2.90008 dB, and not 0 dB as he states.

Everything you never wanted to know about PCM

Reply #8
Of course to the layman the artice will the give the impression of an competent, in-depth technical discussion. So I guess most people would easily be persuated to believe that CDs are inferior Vinyl after reading an article like this.
It is good that you mention this site - you know, I fell for it! I actually fell for it! Especially for the example you quoted, not realizing that this would be for - what? - a 4 bit system?

An exponential system. He mistook the (roughly) 6dB per bit of linear PCM for 6dB per step.

If you wanted to cover 32768 to 1, 0, and -1 to -32768 that way you'd need 5 bits.
And the result would sound like this.

Everything you never wanted to know about PCM

Reply #9
Oddly enough- if you read the entire piece, he is a champion of the digital format rather than a proponent for analog. He is just pointing out the rather well known weaknesses of the 16 bit 44.1 kHz CD format. I have had the luck to be a child of analog, and heard what a well done LP can sound like. As the article states- only a few of us have really heard a well done LP on a system set up to play it. I felt there was to be no digital heaven, as I had been to the analog one first. Luckily for us audio nut cases the DVD has leveled that playing field a bit- like 24 actually. Not to say that 24 bit audio is the end all to analog done well, but it does sound one heck of a lot better than 16 bits could ever hope to.


This is the wrong place to say things like that. We've been pursing the question as to whether or not 24 bits sounds inherently better than 16 bits for any number of years with bias-controlled listening tests and still pretty much come up empty. The problem isn't the medium, the problems are  the message and the people who receive the message. We can't make a message that needs even 16 bits to transmit, and we surely can't easily play it back in such a way that we can truly appreciate it.

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The author also is quick to point out that 32 and 64 bit audio is possible NOW if we as consumers would demand it.


There is no practical reason for consumers to demand 32 or 64 bit recordings. Furthermore, we have been able to distribute 32 or 64 bit recordings for years using computer data formats. Yes, computer data formats requires that they be played with computers, but that is not a stumbling block, if they would provide any practical advantage.

If you search around here you can find down loadable 24 bit recordings and the facilities to do your own listening tests of them with.  What you hear here is not about prejudice but real world practical experience.

Quote
Which is why I am here- looking for any information on using the DVD format as a easy way to play 24 bit 96 kHz formatted audio. Not talking DVD-Audio format- I want to be able to pop a disc into any DVD-Video player on the market, and more specifically the old Sony 200 disc player I use daily as my CD\DVD player. So here's the question of the day: Anyone here use DVD authoring software that has the ability to make a .ISO (.UDF) file with a still image for the video and audio tracks at 24 bit 96 kHz?


DVD-Vs with 24/96 audio tracks came and went in the market place over 5 years ago. I even have an operational Pioneer DV-525 DVD player that plays them. Some of the audiophile recording companies released a few recordings in that format. They did not achieve anything like critical mass in the marketplace. There wasn't even an audible "plop".

Since then SACD and DVD-As have essentially come, not conquered, and are currently dying a slow- death in the marketplace. Tens of millions of dollars were lost and recording industry executives that staked their careers on them have been fired for non-performance.

Quote
I tried the trial copy of HD-Audio Solo Ultra, and all I got were bad .ISO files with errors in it. So I am off to read further but had to respond to this as it was the first thread to come up




 

Everything you never wanted to know about PCM

Reply #11
    
Thanks
TheWellTemperedComputer.com

Everything you never wanted to know about PCM

Reply #12
FWIW I emailed the author of that piece and discussed with him some of his misconceptions.  Hopefully he will correct his mistakes.

Everything you never wanted to know about PCM

Reply #13
http://www.soundfountain.com/amb/cd25years.html
I like the pretty pictures! Quite nostalgic.

Not sure anyone would be convinced either way by this - anyone who takes the time to read something that long has probably already made up their mind.

While not exactly HA / TOS8 in approach, the rest of that website is a joy for anyone who collects old audio equipment. e.g. my Dad had one of these decks (not the speakers)... http://www.soundfountain.com/amb/ttgarrard.html


Now...
That is nothing:

http://www.wired.co.uk/news/archive/2010-08/27/and-vinyly

"In Soviet Russia" turntables play you...
...that is brilliant! What tunes shall I have myself made into...?

Cheers,
David.

Everything you never wanted to know about PCM

Reply #14
I don't see much hope for someone who confuses belief with fact this way:

"When word gets around that Philips will propose a digital disc with the 14 bit/44.1 kHz format, editor/publisher Peter Aczel inspires the readers of The Audio Critic to send postcards to Philips in Eindhoven, the Netherlands, to urge the engineers to choose a sampling frequency of at least 50 kHz.
But in fact even a sampling frequency of 50 kHz. would not be high enough to satisfy the discriminating listener, as only a much higher sampling frequency can produce upper harmonics and a true transient response."


Quote
Already in the early nineteen eighties I remember fantasizing with John Watson (of Mission Electronics at the time) about a very high sampling frequency of say 700,000 Hz. well knowing that this will result in a high resolution sound recording. Or take the sampling frequency of 400,000 Hz. as is the argument of designer Tim de Paravicini in the nineteen nineties. That frequency will give an audio band extending to 200.000 Hz. This means that the number of samples at 20.000 Hz. is 8. And this brings about the resolution a professional reel to reel tape recorder has. And a 6 dB filter - which is phase coherent - at 20,000 Hz. can easily be applied. To some 200,000 Hz. may seem rather far fetched. In the analog days a basic bandwidth of 400,000 Hz. for sophisticated phono stages is not at all uncommon.


This stuff just never goes away. Barry Diament is currently peddling similar tripe about 'time delay' over on Hoffman's forum

Everything you never wanted to know about PCM

Reply #15
Possibly even more scary - some of these articles claim to be web editions of things that have already been published in print (not in English though).

A phono stage with a bandwidth of 400kHz?! I'm not sure what he's thinking - can he be unaware of the typical frequency response of a phono cartridge, never mind the RIAA curve which is 45dB down at 400kHz. I get that the phono stage itself may well have some response out that far - it just seems a bit pointless mentioning it as if it's relevant, given human ears and/or a vinyl source.

Cheers,
David.

Everything you never wanted to know about PCM

Reply #16
Well, it's all about those otherworldly harmonics I guess

 
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