Will Friedwald listens solely to iTunes

[GA Russell]

Here's an interview I found with Will Friedwald, in which he discusses the fact that he no longer listens to CDs, except to audition to see what he will put onto a hard drive:

http://www.glennwolsey.com/2007/04/19/inte...nes-collection/

Interview: Will Friedwald, Owner Of The Worlds Largest iTunes Collection

Apple April 19th, 2007

Will Friedwald proclaims he has the world largest iTunes collection. An avid listener to Jazz music, and a writer for the New York Sun, Will spends his days in front of his Power Mac G5 running “The Maxtix”, his mammoth 200,000 track iTunes library.

Will took some time out of his rigirous daily schudule and took some time to talk with me about iTunes, his music collection, and how he manages it.

The question we all want to know. How large is your iTunes music collection?

I just re-compiled the main library (something that takes about six hours – I only do it a few times a year!). Here are the new stats:

849 GB | 172,150 tracks | 809.2 days

2,935 artists | 11,561 albums

iTunes library database file - 282 MB

iTunes library XML file - 259 MB

For reasons I will get into later, I also have several sub-libraries; theoretically, all my music will eventually go into the main library. I also have a separate “annex” of about 200-300 GB of stuff that I am gradually adding in to the main library. If I were to put everything together, which I am slowly doing, it will be around 1200 GB.

How long have you been using iTunes to manage your digital music collection?

I started using iTunes when I made the leap to OS X, which was in 2003, the year I bought my G3 iBook (which I am still happily using four years later – am typing this on it, as a matter of fact).

Originally, I planned to just transfer a few CD artists into the library – Frank Sinatra, Duke Ellington, Bill Evans, Louis Armstrong, John Coltrane, Ella Fitzgerald, Miles Davis. Then, the next thing I noticed was that iTunes was great for listening to box sets: I could take, for instance, the 18-CD that I did on Nat King Cole (Mosaic Records actually won a Grammy for that in the early ‘90s) and instantly find the track that I wanted to hear.

No more opening a big clunky box, fumbling around to find an individual CD, and then looking for the right track! It was astonishing that as soon as I typed “You Must Be Blind,” there it was! I started transferring all my big boxed sets – especially the Mosaic and Bear Family boxed sets almost immediately.

When was the takeoff point where the library started to drastically grow?

I could tell you “when” in terms of the theoretically breakthrough, if not precisely in terms of calendar time. For the few months or so, I went back and forth between listening via iTunes and listening to standard compact discs.

Then, at a certain point, I realized that I was doing nearly all of my listening via iTunes. In fact, I gradually reached the point where I am now, and that is the only time I listen to standard CDs now is when I am “auditioning” them to see if I want to put them into iTunes.

Early on, I didn’t want to make my iBook internal hard drive work so hard to house all that music, so I purchased my first of many external drives (it may have been 160 GB, which at that time I thought would last me forever!). Then I bought a used blueberry iMac just to run iTunes – and that held me for a while.

But basically, it was at the point that I began doing all my listening via iTunes that the library began to grow exponentially. When I started to put every piece of music I thought I would ever listen to again, I began referring to the iTunes music library as “The Jazz Matrix” – although since then I have shortened it to just “The Matrix.”

How many tracks do you add to your library each week?

I couldn’t really estimate in terms of a number; the way I work is, this week, for instance, I did a feature article for my paper (The New York Sun) on Charles Mingus, which ran today (Monday 4/16) in honor of his the 85th Anniversary of Mingus’s birth. Since I wanted to listen to as much of his music as possible, I loaded all of my Mingus CDs into The Matrix. I have about 50 albums by Mingus, some of which were already in there, but I added all the others.

It’s an incredible tool for someone writing about music, to be instantly able to listen and compare every recording of “Fables of Faubus” and see how they differ from one another.

Right now I have two Mac OS X desktops – a G5 Power Mac and the G3 iMac – I use them both for importing. There are some days when I just keep the iMac going all day long; I just keep feeding the beast, when The Matrix yells “feed me!” It’s the only way to tackle some of the more prolific artists in the history of recording, and massive projects like the 17-CD Complete Art Pepper Galaxy Sessions box.

I also have also added massive amounts of material that otherwise only exists in the analog domain – CDRs transferred from LPs and 78s that have not been digitally remastered.

What do you like about using iTunes to manage your library?

iTunes is, without a doubt, the best and most intuitive program out there for transferring, archiving, and listening to music – not to mention buying it from the store and putting it on an iPod. There’s nothing I’ve seen that has its ease of use, and its flexibility – especially with the aid of the applescripts made available by Doug Adams.

With a smallish library, especially, it is incredibly easy to compile playlists, to search for songs using any criteria. I particularly like that you can search by criteria other than recording artist; much of the time I look for music by composer, so I do a search under “Gershwin” or “Ellington” and all of a sudden, every recording of a song by thousands of different performers magically appears. If anyone has a better music program, bring it on!

What things would you like to be added/improved within the application?

I’ve actually written an editorial essay about the limitations of iTunes (which hasn’t been published yet), where I talk about some of these issues, but it to boil it down to a paragraph or less:

Essentially the problem is that iTunes was designed for people to buy music from the store, to put CDs on their iPods, and then, perhaps lastly, to store some of a personal CD collection in the library. It was NOT designed for what I am doing with it, which is to store, manage and access a major music collection of nearly 200,000 tracks. As a result, when I am working with the full 800 GB library, it is painfully slow, getting around the library, doing searches, and editing info on individual tracks or whole albums just takes forever!

As an example: when I want to edit the information on an individual song – the “metadata” as technically-minded people call it – I highlight the track, then I press Apple-I. With a small library (under 50-100 GB), the edit info window comes up instantly. But with my 800 GB Matrix, I have to wait three or four minutes before the window comes up. That’s time enough to go to the bathroom, make a cup of coffee, or entertain myself with 99% of the clips on youtube!

As I see it, there are two possible solutions (other than using multiple libraries, which I am doing now, but which is more of a temporary workaround than a long-term solution):

The first (which is quicker but more expensive) is to get faster hardware, although I am not even sure if one of the new 8-core Mac Pro desktops could process a 1000-GB music library as fast as I would like it to. (Not that I can remotely afford a fully-outfitted new Mac Pro!)

The second is a vague but hopefully optimistic possibility for the future: I find that more and more individuals out there are getting saddled with these mega-libraries like mine. Also, at a certain point, institutions like The Library of Congress, The Smithsonian, and, most importantly, the Rutgers Institute of Jazz Studies, are going to want to make their collections of recorded sound available in a digital system. Right now, as far as I know, the technology to do that does not exist – it certainly would be very difficult to do that using iTunes as it currently exists.

What I would like to see Apple do is build a specific program to address this need. The same way that there are several levels of Final Cut, why couldn’t there be an upgraded edition of iTunes – something like iTunes Pro or Super-iTunes? This new program, obviously wouldn’t be a freebie, but if it could do what I want it to do I would gladly pay Apple almost anything that it wants. $200 for new software is a lot cheaper than having to spend $4000 for a new Mac Pro!

How much time are you spending building, organizing, and listening to your music on a daily basis?

Way longer than I should! I usually start the day by importing a few Cds as I answer the morning email and downing my first cup of coffee. As I’m working on a story, I keep on importing – somethings transferring two discs at once simultaneously on the G5 and the iMac. I’m forever tinkering with the library, several hours a day, often when I’m on the phone, sometimes even when I’m watching TV (on the extremely rare nights when I’m not out covering live music).

What genres of music do you most enjoy listening to?

I’m essentially a jazz guy: I review jazz in New York for The New York Sun, which boasts the best arts section of any NYC newspaper (even the Times – it’s true!). I’ve written a bunch of books on jazz and pop singers, but I write mostly about instrumental jazz for the paper.

Lately I’ve had more of an appreciation for classic rock, though there’s still very little from after 1970 that I listen to, pop-music wise. I also have nearly every original Broadway cast album in the matrix, and lots of classic country. When it comes to classical music, I’ve been using Rhapsody, since I don’t have enough of my own personal classical CD collection to make it worthwhile. As of now, there is no Classical Matrix, but maybe someday soon.

What hardware are you using to run your mammoth collection?

In 2005, I invested in a single-processor G5 PowerMac, and that has powered the collection ever since. The Matrix is currently housed in a mirrored SATA RAID array of three four-hundred GB drives (3 x 400) in a Transintl enclosure. (I have recently learned, to my great annoyance, that I can’t get PCI-X on my G5, which might have helped to speed things up a bit.)

I also do frequent back-ups, using a PCI magic bridge and three barebones external SATA drives.

849GB, 172,150 tracks, and 809.2 days of listening pleasure. Envy the collection?

edit for spelling

Edited April 20, 2007 by GA Russell

[bertrand]

1) He said he was going to boil his description of the limitations of iTunes down to a paragraph or less, then uses 10 or so.

2) I bet my playlists are way cooler.

Bertrand.

[jazzbo]

I wouldn't take that bet!

Wow. That's a lot of work he's done.

[porcy62]

I am a bit ill-at-ease in front of things like this. It reminds me Borges's "The Library of Babel". Though I admit that if listening to music is your job, it could be very usueful.

Edited April 20, 2007 by porcy62

[BruceH]

Only 172 thousand tracks? Is that ALL?????

[kh1958]

Does he just load every track from a CD into his library?

I like to be discriminating and only load the tracks that I like, whether it's one track or the entire CD.

My 10,000 plus itunes library nonetheless now seems puny.

[Larry Kart]

ya'll know who Friedwald's old man was, right?

edc

Lincoln Kirstein?

[Vimes]

I thought this might be of interest - I saved it a year or two back, but the original URL is long gone. Nevertheless, its worth a glance!

iPods by a sound engineer

My wife got herself an iPod music player. I was volunteered to fill it with her music from her CDs. You can get one like her 4GB white Nano here or here.

iTunes is Apple's free software used to copy all your CDs into an iPod. It also allows you to play and manage your entire CD library from your computer, and it sounds great for serious listening.

I had never bothered with these little players or compressed digital audio since I presumed the sound quality was awful. WRONG! The little things sound great for serious music listening, presuming you click a couple of the right buttons in iTunes' preferences. I'll explain these in this article.

I was prejudiced after decades of designing my own recording equipment and working in and around the music and recording industries. Not only have I understood all the math behind digital since the 1970s, I even worked with one of the original designers of the MPEG audio standard and delivered a paper to the audio engineering industry's standards-setting body, the AES, in the 1990s. I've been a member of the AES also since the 1970s. Back a few years ago compressed digital audio wasn't that great and even at 384kbs you were making excuses.

Today the AAC coder in iTunes sounds great at 128kbs, and that's for serious listening on high-end audiophile systems with your eyes closed and your full attention on the music. Just plug in a set of professional headphones that cost more than the iPod, or plug the one ounce Nano, which is smaller than a business card and 1/4" thick, into a 400 pound classical recording studio monitoring system and you'll have the same epiphany I did.

Let me tell you how to do it. Some odd people prefer listening to the equipment and not the music. We call those people audiophiles as opposed to music lovers. Audiophiles share the same prejudice I just overcame against compressed digital audio. For them iTunes also allows recording music without any data loss and also at 96kHz sampling rates. I'll get to that later.

WHAT BOXES TO CHECK

Error Correction

I'm amazed that I caught Apple in a technical faux-pas. If you use iTunes' default importing options you will probably get an occasional click in your sound. That's because under PREFERENCES > ADVANCED > IMPORTING Apple left the "Use Error Correction" box unchecked. This means when any inevitable invisible speck of dust covers a couple of bits on your CD that you may get a click or short dropouts. It drove me nuts at first thinking I had a dirty connection on playback. I never thought Apple could make such an obvious mistake.

CDs always need error correction. Without error correction you'll always have problems. Every CD player and every CD-ROM reader always applies error correction without you ever having to ask. CDs don't work without it.

CHECK THE "USE ERROR CORRECTION" BOX under PREFERENCES > ADVANCED > IMPORTING. Once I did I've never had a problem.

Apple cautions that checking this may take more time to import. So what? It takes no longer from what I can see, and without checking it you'll wind up having to re-import everything as I did. If it does take any longer it's because it's saving music that otherwise would be useless.

Encoder Preference

After finding Apple's error correction blunder I decided to spend the day experimenting on myself to hear what I could hear for encoder quality. I used my reference Beer DT990 headphones, since I can hear more through them than my Quad ESL63 electrostatics or B&W 801 studio monitors. I compared results using a stack of our favorite commercial CDs.

I was struck with how great this all sounds today. Even the distortions introduced by crummy digital audio compression are nicer than the distortions in previous consumer distribution media like LP vinyl records and cassette tapes. The great thing about CDs is that they offer consumers the same quality we took for granted from master tapes, but never heard outside a studio until CDs came along. Even master tapes are gone today. Today music is recorded uncompressed on hard drives. Back to the story:

At the lower rates the audible distortions are swishy phasing effects, especially audible on choral backgrounds during percussive events. I knew that. These are the same weird sounds one hears over cell phones. At the bit rates used for music these only happen if you really listen for them.

The most surprising and annoying defect is alteration to the stereo image. I first heard this with a true stereo (two-mike) choral recording. The natural reverberation decayed normally, and depending on the data rate would eventually decay to mono! At higher rates it's fine and at 96kbs it sounded weird when I first heard it. There's an obvious explanation for this. Data compression is all about eliminating redundancy. The more uniform the sound the easier it is to compress. Music compression takes a lot of advantage that most music is similar in both channels. Natural stereo reverberation becomes completely random with zero correlation between channels. Therefore it's much tougher to compress a reverb tail than the program sometimes, which is why the lower rate encoders gave up and summed it to mono at low levels.

The biggest audible defects at lower rates today aren't obvious things to which you can point a new listener, like clicks or pings. The degradation is a loss of stereo space and image. This becomes obvious on headphones. You'd probably never notice on speakers, and never if you're doing something else while playing music.

128kbs AAC

iTunes 6 uses 128 kbs AAC as default. This is fine. I really have to use my imagination to make myself think I hear any difference between audio coded that way and the original CD.

I could almost hear the ends of reverb tails in one classical recording sum to mono and that was about the only defect.

This default is fine, especially if you have an old iPod which can't handle the variable bit rates which sound better below. With a newer iPod I use:

128 kbs Variable Bit Rate (VBR) AAC : My Choice

For only about a 5% penalty in file size I use variable bit rate encoding for better quality. This lets the coder use more bits when it has to. I set this under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom, and then check "Use Variable Bit Rate Encoding (VBR)." Apple has this pretty well hidden. I leave the rest at default of 128kbs, auto and auto.

VBR sounds better for the same file size. As far as I can see the only reason Apple doesn't default to this is for compatibility with old iPods. Having a new iPod Nano, no problem!

I couldn't hear any defects. 128kbs VBR AAC sounds the same as my CDs. Any defects I heard were accurate reproductions of flaws in the original CDs.

96kbs AAC

96kbs AAC sounds fine for normal use while not paying rapt attention to your music.

It sounds worse than the others listening carefully. It got a little bit swimmy, phasey or flangey if you compared it to the original, and the ends of classical reverb tails would sum to mono if you were paying close attention.

I'd not use this unless you're stuck on an old iPod which can't handle VBR.

96kbs VBR

96kbs VBR sounds better than regular 96kbs. It's not much bigger, maybe 5%, in file size. I can hear a difference between regular and VBR at 96kbs.

I can't hear a difference between 128kbs standard and 128kbs VBR. The reason I chose 128kbs VBR over 128kbs standard is because I can hear the difference at 96kbs. This way I've got some extra, although inaudible, quality improvement over 128kbs standard with almost no file size penalty.

Since 96kbs VBR is about the same size as regular 96kbs I'd suggest 96kbs VBR if you're really trying to cram in as much music as possible. I wouldn't notice anything wrong if I was doing something else while listening, which is how most people listen.

160kbs VBR

I also tried this. It makes bigger files and I couldn't hear any improvement over 128kbs VBR. 128kbs VBR sounded identical to my CDs.

WHAT IS AAC?

AAC is one of many ways to compress audio files. MP3 is another. There are many people with PhDs who spend careers developing and comparing them. Many thanks to these people whose work has given us transparent audio quality at 128kbs.

I didn't go off and try to compare all these systems. It took a day just to compare a few bit rates of AAC. My research was trying to find an optimum setting for getting my wife's CDs into her iPod with the best possible quality at the smallest file size.

I'm a music lover who prefers listening to music over comparing coding schemes.

Encoders get better every year. That's why 128kbs sounds better today than 384kbs used to sound. MP3, actually MPEG-2 layer 3, was OK several years ago and is has established itself as a popular format for illegally copied music. AAC works better today. Better means better sound for the same file size, or smaller files for the same quality. You have to ask yourself if it makes sense to re-encode all your stuff every couple of years for better sound and smaller files. Today I'd skip MP3.

I'm not going to explain AAC itself, sorry. I already explained all this in a paper I delivered some years ago. You can find this and info on all the other compression systems elsewhere in the Internet.

HOW ABOUT THOSE AUDIOPHILES?

For them there is lossless coding which preserves each and every bit of audio data. They would select Apple Lossless Coder under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom.

This lossless coder makes big files, about five times as big as 128kbs VBR.

I find 128kbs VBR transparent. If I was really worried about things I can't hear I'd use a higher rate AAC VBR setting, like 160kbs or 256kbs.

The beauty of iPod and iTunes is that you have the flexibility to use any of these schemes, and that it sounds great if you leave everything alone so long as you remember to check "Use Error Correction" as I warned at the top.

Audio has come a long way. Again.

[porcy62]

Vimes,

you forgot to put the name of the author of the very interesting articles.

One small consideration, as audiophile and music lover. I found quite bothering the distinction, though it may exist in some cases.

The most bothering thing to me is that all these audio enigineers, technicians, the AES, companies executives, the RIAA ecc.. treated us, the customers, as dumb for decades since the invention of phonographe! Every new invention, from the shellac to MP3, everytime they treated us like dumb customer.

Hey! look at this! This the best ultimate revolution in quality, durability, ease! Buy it! You can't live without it!

And when some customers, tyred of all these lectures from self appointed experts, dare to say that they are not going to replace their long coveted and huge collection or records, cds, with the latest Hi-Rez or lossless encoding because to their ears vinyls or cds just sound fine to them, and often better, then new formats (look at the vinyl vs cd in the early days), they are treated like dumb, deaf, idiotic nostalgic, psychopats that hear nonexistent voices in their damaged brains.

You know what? Buy you damn lossless files from iTunes, your hard disk music servers and all the damn new stuff the tycoons of the music industry put on the market. I've already done with it!

P.S. Vimes, I am not targetting you, it's just a vent of a dumb, deaf, idiotic nostalgic, psychopat

[J Larsen]

I thought this might be of interest - I saved it a year or two back, but the original URL is long gone. Nevertheless, its worth a glance!

iPods by a sound engineer

My wife got herself an iPod music player. I was volunteered to fill it with her music from her CDs. You can get one like her 4GB white Nano here or here.

iTunes is Apple's free software used to copy all your CDs into an iPod. It also allows you to play and manage your entire CD library from your computer, and it sounds great for serious listening.

I had never bothered with these little players or compressed digital audio since I presumed the sound quality was awful. WRONG! The little things sound great for serious music listening, presuming you click a couple of the right buttons in iTunes' preferences. I'll explain these in this article.

I was prejudiced after decades of designing my own recording equipment and working in and around the music and recording industries. Not only have I understood all the math behind digital since the 1970s, I even worked with one of the original designers of the MPEG audio standard and delivered a paper to the audio engineering industry's standards-setting body, the AES, in the 1990s. I've been a member of the AES also since the 1970s. Back a few years ago compressed digital audio wasn't that great and even at 384kbs you were making excuses.

Today the AAC coder in iTunes sounds great at 128kbs, and that's for serious listening on high-end audiophile systems with your eyes closed and your full attention on the music. Just plug in a set of professional headphones that cost more than the iPod, or plug the one ounce Nano, which is smaller than a business card and 1/4" thick, into a 400 pound classical recording studio monitoring system and you'll have the same epiphany I did.

Let me tell you how to do it. Some odd people prefer listening to the equipment and not the music. We call those people audiophiles as opposed to music lovers. Audiophiles share the same prejudice I just overcame against compressed digital audio. For them iTunes also allows recording music without any data loss and also at 96kHz sampling rates. I'll get to that later.

WHAT BOXES TO CHECK

Error Correction

I'm amazed that I caught Apple in a technical faux-pas. If you use iTunes' default importing options you will probably get an occasional click in your sound. That's because under PREFERENCES > ADVANCED > IMPORTING Apple left the "Use Error Correction" box unchecked. This means when any inevitable invisible speck of dust covers a couple of bits on your CD that you may get a click or short dropouts. It drove me nuts at first thinking I had a dirty connection on playback. I never thought Apple could make such an obvious mistake.

CDs always need error correction. Without error correction you'll always have problems. Every CD player and every CD-ROM reader always applies error correction without you ever having to ask. CDs don't work without it.

CHECK THE "USE ERROR CORRECTION" BOX under PREFERENCES > ADVANCED > IMPORTING. Once I did I've never had a problem.

Apple cautions that checking this may take more time to import. So what? It takes no longer from what I can see, and without checking it you'll wind up having to re-import everything as I did. If it does take any longer it's because it's saving music that otherwise would be useless.

Encoder Preference

After finding Apple's error correction blunder I decided to spend the day experimenting on myself to hear what I could hear for encoder quality. I used my reference Beer DT990 headphones, since I can hear more through them than my Quad ESL63 electrostatics or B&W 801 studio monitors. I compared results using a stack of our favorite commercial CDs.

I was struck with how great this all sounds today. Even the distortions introduced by crummy digital audio compression are nicer than the distortions in previous consumer distribution media like LP vinyl records and cassette tapes. The great thing about CDs is that they offer consumers the same quality we took for granted from master tapes, but never heard outside a studio until CDs came along. Even master tapes are gone today. Today music is recorded uncompressed on hard drives. Back to the story:

At the lower rates the audible distortions are swishy phasing effects, especially audible on choral backgrounds during percussive events. I knew that. These are the same weird sounds one hears over cell phones. At the bit rates used for music these only happen if you really listen for them.

The most surprising and annoying defect is alteration to the stereo image. I first heard this with a true stereo (two-mike) choral recording. The natural reverberation decayed normally, and depending on the data rate would eventually decay to mono! At higher rates it's fine and at 96kbs it sounded weird when I first heard it. There's an obvious explanation for this. Data compression is all about eliminating redundancy. The more uniform the sound the easier it is to compress. Music compression takes a lot of advantage that most music is similar in both channels. Natural stereo reverberation becomes completely random with zero correlation between channels. Therefore it's much tougher to compress a reverb tail than the program sometimes, which is why the lower rate encoders gave up and summed it to mono at low levels.

The biggest audible defects at lower rates today aren't obvious things to which you can point a new listener, like clicks or pings. The degradation is a loss of stereo space and image. This becomes obvious on headphones. You'd probably never notice on speakers, and never if you're doing something else while playing music.

128kbs AAC

iTunes 6 uses 128 kbs AAC as default. This is fine. I really have to use my imagination to make myself think I hear any difference between audio coded that way and the original CD.

I could almost hear the ends of reverb tails in one classical recording sum to mono and that was about the only defect.

This default is fine, especially if you have an old iPod which can't handle the variable bit rates which sound better below. With a newer iPod I use:

128 kbs Variable Bit Rate (VBR) AAC : My Choice

For only about a 5% penalty in file size I use variable bit rate encoding for better quality. This lets the coder use more bits when it has to. I set this under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom, and then check "Use Variable Bit Rate Encoding (VBR)." Apple has this pretty well hidden. I leave the rest at default of 128kbs, auto and auto.

VBR sounds better for the same file size. As far as I can see the only reason Apple doesn't default to this is for compatibility with old iPods. Having a new iPod Nano, no problem!

I couldn't hear any defects. 128kbs VBR AAC sounds the same as my CDs. Any defects I heard were accurate reproductions of flaws in the original CDs.

96kbs AAC

96kbs AAC sounds fine for normal use while not paying rapt attention to your music.

It sounds worse than the others listening carefully. It got a little bit swimmy, phasey or flangey if you compared it to the original, and the ends of classical reverb tails would sum to mono if you were paying close attention.

I'd not use this unless you're stuck on an old iPod which can't handle VBR.

96kbs VBR

96kbs VBR sounds better than regular 96kbs. It's not much bigger, maybe 5%, in file size. I can hear a difference between regular and VBR at 96kbs.

I can't hear a difference between 128kbs standard and 128kbs VBR. The reason I chose 128kbs VBR over 128kbs standard is because I can hear the difference at 96kbs. This way I've got some extra, although inaudible, quality improvement over 128kbs standard with almost no file size penalty.

Since 96kbs VBR is about the same size as regular 96kbs I'd suggest 96kbs VBR if you're really trying to cram in as much music as possible. I wouldn't notice anything wrong if I was doing something else while listening, which is how most people listen.

160kbs VBR

I also tried this. It makes bigger files and I couldn't hear any improvement over 128kbs VBR. 128kbs VBR sounded identical to my CDs.

WHAT IS AAC?

AAC is one of many ways to compress audio files. MP3 is another. There are many people with PhDs who spend careers developing and comparing them. Many thanks to these people whose work has given us transparent audio quality at 128kbs.

I didn't go off and try to compare all these systems. It took a day just to compare a few bit rates of AAC. My research was trying to find an optimum setting for getting my wife's CDs into her iPod with the best possible quality at the smallest file size.

I'm a music lover who prefers listening to music over comparing coding schemes.

Encoders get better every year. That's why 128kbs sounds better today than 384kbs used to sound. MP3, actually MPEG-2 layer 3, was OK several years ago and is has established itself as a popular format for illegally copied music. AAC works better today. Better means better sound for the same file size, or smaller files for the same quality. You have to ask yourself if it makes sense to re-encode all your stuff every couple of years for better sound and smaller files. Today I'd skip MP3.

I'm not going to explain AAC itself, sorry. I already explained all this in a paper I delivered some years ago. You can find this and info on all the other compression systems elsewhere in the Internet.

HOW ABOUT THOSE AUDIOPHILES?

For them there is lossless coding which preserves each and every bit of audio data. They would select Apple Lossless Coder under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom.

This lossless coder makes big files, about five times as big as 128kbs VBR.

I find 128kbs VBR transparent. If I was really worried about things I can't hear I'd use a higher rate AAC VBR setting, like 160kbs or 256kbs.

The beauty of iPod and iTunes is that you have the flexibility to use any of these schemes, and that it sounds great if you leave everything alone so long as you remember to check "Use Error Correction" as I warned at the top.

Audio has come a long way. Again.

A couple things struck me - I always assumed that the error correction option referred to the internal error correction for the iPod's harddrive - NOT the error correction on your cd-rom drive when you are importing your CD. I'll have to double check wih one of my buddies about this, but I always thought that CDs literally could not work at all without error correction - the beam doesn't focus on a single bit, it focuses on a an area on the disc, and needs to find at least three data points w/in any given area to make a bit.

Secondly, the guy starts off talking about how he had previously "never bothered with these little players or compressed digital audio," but then to buy himself some credibility on the subject asserts that he has worked in exactly that field since the 70s and "delivered a paper" on AAC "years ago" - WTF???

I'm not saying the guy is a charlatan, but you combine the second apparent contradiction with what I believe to be an obvious technical gaffe on CDs and I do have to wonder a little....

What is the guy's name?

Edited April 25, 2007 by J Larsen

[porcy62]

I thought this might be of interest - I saved it a year or two back, but the original URL is long gone. Nevertheless, its worth a glance!

iPods by a sound engineer

My wife got herself an iPod music player. I was volunteered to fill it with her music from her CDs. You can get one like her 4GB white Nano here or here.

iTunes is Apple's free software used to copy all your CDs into an iPod. It also allows you to play and manage your entire CD library from your computer, and it sounds great for serious listening.

I had never bothered with these little players or compressed digital audio since I presumed the sound quality was awful. WRONG! The little things sound great for serious music listening, presuming you click a couple of the right buttons in iTunes' preferences. I'll explain these in this article.

I was prejudiced after decades of designing my own recording equipment and working in and around the music and recording industries. Not only have I understood all the math behind digital since the 1970s, I even worked with one of the original designers of the MPEG audio standard and delivered a paper to the audio engineering industry's standards-setting body, the AES, in the 1990s. I've been a member of the AES also since the 1970s. Back a few years ago compressed digital audio wasn't that great and even at 384kbs you were making excuses.

Today the AAC coder in iTunes sounds great at 128kbs, and that's for serious listening on high-end audiophile systems with your eyes closed and your full attention on the music. Just plug in a set of professional headphones that cost more than the iPod, or plug the one ounce Nano, which is smaller than a business card and 1/4" thick, into a 400 pound classical recording studio monitoring system and you'll have the same epiphany I did.

Let me tell you how to do it. Some odd people prefer listening to the equipment and not the music. We call those people audiophiles as opposed to music lovers. Audiophiles share the same prejudice I just overcame against compressed digital audio. For them iTunes also allows recording music without any data loss and also at 96kHz sampling rates. I'll get to that later.

WHAT BOXES TO CHECK

Error Correction

I'm amazed that I caught Apple in a technical faux-pas. If you use iTunes' default importing options you will probably get an occasional click in your sound. That's because under PREFERENCES > ADVANCED > IMPORTING Apple left the "Use Error Correction" box unchecked. This means when any inevitable invisible speck of dust covers a couple of bits on your CD that you may get a click or short dropouts. It drove me nuts at first thinking I had a dirty connection on playback. I never thought Apple could make such an obvious mistake.

CDs always need error correction. Without error correction you'll always have problems. Every CD player and every CD-ROM reader always applies error correction without you ever having to ask. CDs don't work without it.

CHECK THE "USE ERROR CORRECTION" BOX under PREFERENCES > ADVANCED > IMPORTING. Once I did I've never had a problem.

Apple cautions that checking this may take more time to import. So what? It takes no longer from what I can see, and without checking it you'll wind up having to re-import everything as I did. If it does take any longer it's because it's saving music that otherwise would be useless.

Encoder Preference

After finding Apple's error correction blunder I decided to spend the day experimenting on myself to hear what I could hear for encoder quality. I used my reference Beer DT990 headphones, since I can hear more through them than my Quad ESL63 electrostatics or B&W 801 studio monitors. I compared results using a stack of our favorite commercial CDs.

I was struck with how great this all sounds today. Even the distortions introduced by crummy digital audio compression are nicer than the distortions in previous consumer distribution media like LP vinyl records and cassette tapes. The great thing about CDs is that they offer consumers the same quality we took for granted from master tapes, but never heard outside a studio until CDs came along. Even master tapes are gone today. Today music is recorded uncompressed on hard drives. Back to the story:

At the lower rates the audible distortions are swishy phasing effects, especially audible on choral backgrounds during percussive events. I knew that. These are the same weird sounds one hears over cell phones. At the bit rates used for music these only happen if you really listen for them.

The most surprising and annoying defect is alteration to the stereo image. I first heard this with a true stereo (two-mike) choral recording. The natural reverberation decayed normally, and depending on the data rate would eventually decay to mono! At higher rates it's fine and at 96kbs it sounded weird when I first heard it. There's an obvious explanation for this. Data compression is all about eliminating redundancy. The more uniform the sound the easier it is to compress. Music compression takes a lot of advantage that most music is similar in both channels. Natural stereo reverberation becomes completely random with zero correlation between channels. Therefore it's much tougher to compress a reverb tail than the program sometimes, which is why the lower rate encoders gave up and summed it to mono at low levels.

The biggest audible defects at lower rates today aren't obvious things to which you can point a new listener, like clicks or pings. The degradation is a loss of stereo space and image. This becomes obvious on headphones. You'd probably never notice on speakers, and never if you're doing something else while playing music.

128kbs AAC

iTunes 6 uses 128 kbs AAC as default. This is fine. I really have to use my imagination to make myself think I hear any difference between audio coded that way and the original CD.

I could almost hear the ends of reverb tails in one classical recording sum to mono and that was about the only defect.

This default is fine, especially if you have an old iPod which can't handle the variable bit rates which sound better below. With a newer iPod I use:

128 kbs Variable Bit Rate (VBR) AAC : My Choice

For only about a 5% penalty in file size I use variable bit rate encoding for better quality. This lets the coder use more bits when it has to. I set this under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom, and then check "Use Variable Bit Rate Encoding (VBR)." Apple has this pretty well hidden. I leave the rest at default of 128kbs, auto and auto.

VBR sounds better for the same file size. As far as I can see the only reason Apple doesn't default to this is for compatibility with old iPods. Having a new iPod Nano, no problem!

I couldn't hear any defects. 128kbs VBR AAC sounds the same as my CDs. Any defects I heard were accurate reproductions of flaws in the original CDs.

96kbs AAC

96kbs AAC sounds fine for normal use while not paying rapt attention to your music.

It sounds worse than the others listening carefully. It got a little bit swimmy, phasey or flangey if you compared it to the original, and the ends of classical reverb tails would sum to mono if you were paying close attention.

I'd not use this unless you're stuck on an old iPod which can't handle VBR.

96kbs VBR

96kbs VBR sounds better than regular 96kbs. It's not much bigger, maybe 5%, in file size. I can hear a difference between regular and VBR at 96kbs.

I can't hear a difference between 128kbs standard and 128kbs VBR. The reason I chose 128kbs VBR over 128kbs standard is because I can hear the difference at 96kbs. This way I've got some extra, although inaudible, quality improvement over 128kbs standard with almost no file size penalty.

Since 96kbs VBR is about the same size as regular 96kbs I'd suggest 96kbs VBR if you're really trying to cram in as much music as possible. I wouldn't notice anything wrong if I was doing something else while listening, which is how most people listen.

160kbs VBR

I also tried this. It makes bigger files and I couldn't hear any improvement over 128kbs VBR. 128kbs VBR sounded identical to my CDs.

WHAT IS AAC?

AAC is one of many ways to compress audio files. MP3 is another. There are many people with PhDs who spend careers developing and comparing them. Many thanks to these people whose work has given us transparent audio quality at 128kbs.

I didn't go off and try to compare all these systems. It took a day just to compare a few bit rates of AAC. My research was trying to find an optimum setting for getting my wife's CDs into her iPod with the best possible quality at the smallest file size.

I'm a music lover who prefers listening to music over comparing coding schemes.

Encoders get better every year. That's why 128kbs sounds better today than 384kbs used to sound. MP3, actually MPEG-2 layer 3, was OK several years ago and is has established itself as a popular format for illegally copied music. AAC works better today. Better means better sound for the same file size, or smaller files for the same quality. You have to ask yourself if it makes sense to re-encode all your stuff every couple of years for better sound and smaller files. Today I'd skip MP3.

I'm not going to explain AAC itself, sorry. I already explained all this in a paper I delivered some years ago. You can find this and info on all the other compression systems elsewhere in the Internet.

HOW ABOUT THOSE AUDIOPHILES?

For them there is lossless coding which preserves each and every bit of audio data. They would select Apple Lossless Coder under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom.

This lossless coder makes big files, about five times as big as 128kbs VBR.

I find 128kbs VBR transparent. If I was really worried about things I can't hear I'd use a higher rate AAC VBR setting, like 160kbs or 256kbs.

The beauty of iPod and iTunes is that you have the flexibility to use any of these schemes, and that it sounds great if you leave everything alone so long as you remember to check "Use Error Correction" as I warned at the top.

Audio has come a long way. Again.

A couple things struck me - I always assumed that the error correction option referred to the internal error correction for the iPod's harddrive - NOT the error correction on your cd-rom drive when you are importing your CD. I'll have to double check wih one of my buddies about this, but I always thought that CDs literally could not work at all without error correction - the beam doesn't focus on a single bit, it focuses on a an area on the disc, and needs to find at least three data points w/in any given area to make a bit.

Secondly, the guy starts off talking about how he had previously "never bothered with these little players or compressed digital audio," but then to buy himself some credibility on the subject asserts that he has worked in exactly that field since the 70s and "delivered a paper" on AAC "years ago" - WTF???

I'm not saying the guy is a charlatan, but you combine the second apparent contradiction with what I believe to be an obvious technical gaffe on CDs and I do have to wonder a little....

What is the guy's name?

Good points, though I am not sure about your theory about the three points, I mean I always thought that the error correction occurs when the three point are not exactly 'aligned' (?), so the processor extapolates the signal from some algoritms. Nowadays it should really matters in term of sound quality expecially when you consider the amount of researches of cd-rom and cd player manufacturers in order to mimimize the effect of error correction in their products. And the same effort of Toshiba Lab to produce software that has the minimum of errors in it.

[Jim Alfredson]

Well, the other contradiction is that if every CD-ROM and CD player uses error correction and can't function properly without it, then how do you even import audio from a CD-ROM into iTunes with that box unchecked? It seems like it wouldn't work at all.

I think J Larsen is correct and that button is for Apple's own hardware error correction.

[J Larsen]

I thought this might be of interest - I saved it a year or two back, but the original URL is long gone. Nevertheless, its worth a glance!

iPods by a sound engineer

My wife got herself an iPod music player. I was volunteered to fill it with her music from her CDs. You can get one like her 4GB white Nano here or here.

iTunes is Apple's free software used to copy all your CDs into an iPod. It also allows you to play and manage your entire CD library from your computer, and it sounds great for serious listening.

I had never bothered with these little players or compressed digital audio since I presumed the sound quality was awful. WRONG! The little things sound great for serious music listening, presuming you click a couple of the right buttons in iTunes' preferences. I'll explain these in this article.

I was prejudiced after decades of designing my own recording equipment and working in and around the music and recording industries. Not only have I understood all the math behind digital since the 1970s, I even worked with one of the original designers of the MPEG audio standard and delivered a paper to the audio engineering industry's standards-setting body, the AES, in the 1990s. I've been a member of the AES also since the 1970s. Back a few years ago compressed digital audio wasn't that great and even at 384kbs you were making excuses.

Today the AAC coder in iTunes sounds great at 128kbs, and that's for serious listening on high-end audiophile systems with your eyes closed and your full attention on the music. Just plug in a set of professional headphones that cost more than the iPod, or plug the one ounce Nano, which is smaller than a business card and 1/4" thick, into a 400 pound classical recording studio monitoring system and you'll have the same epiphany I did.

Let me tell you how to do it. Some odd people prefer listening to the equipment and not the music. We call those people audiophiles as opposed to music lovers. Audiophiles share the same prejudice I just overcame against compressed digital audio. For them iTunes also allows recording music without any data loss and also at 96kHz sampling rates. I'll get to that later.

WHAT BOXES TO CHECK

Error Correction

I'm amazed that I caught Apple in a technical faux-pas. If you use iTunes' default importing options you will probably get an occasional click in your sound. That's because under PREFERENCES > ADVANCED > IMPORTING Apple left the "Use Error Correction" box unchecked. This means when any inevitable invisible speck of dust covers a couple of bits on your CD that you may get a click or short dropouts. It drove me nuts at first thinking I had a dirty connection on playback. I never thought Apple could make such an obvious mistake.

CDs always need error correction. Without error correction you'll always have problems. Every CD player and every CD-ROM reader always applies error correction without you ever having to ask. CDs don't work without it.

CHECK THE "USE ERROR CORRECTION" BOX under PREFERENCES > ADVANCED > IMPORTING. Once I did I've never had a problem.

Apple cautions that checking this may take more time to import. So what? It takes no longer from what I can see, and without checking it you'll wind up having to re-import everything as I did. If it does take any longer it's because it's saving music that otherwise would be useless.

Encoder Preference

After finding Apple's error correction blunder I decided to spend the day experimenting on myself to hear what I could hear for encoder quality. I used my reference Beer DT990 headphones, since I can hear more through them than my Quad ESL63 electrostatics or B&W 801 studio monitors. I compared results using a stack of our favorite commercial CDs.

I was struck with how great this all sounds today. Even the distortions introduced by crummy digital audio compression are nicer than the distortions in previous consumer distribution media like LP vinyl records and cassette tapes. The great thing about CDs is that they offer consumers the same quality we took for granted from master tapes, but never heard outside a studio until CDs came along. Even master tapes are gone today. Today music is recorded uncompressed on hard drives. Back to the story:

At the lower rates the audible distortions are swishy phasing effects, especially audible on choral backgrounds during percussive events. I knew that. These are the same weird sounds one hears over cell phones. At the bit rates used for music these only happen if you really listen for them.

The most surprising and annoying defect is alteration to the stereo image. I first heard this with a true stereo (two-mike) choral recording. The natural reverberation decayed normally, and depending on the data rate would eventually decay to mono! At higher rates it's fine and at 96kbs it sounded weird when I first heard it. There's an obvious explanation for this. Data compression is all about eliminating redundancy. The more uniform the sound the easier it is to compress. Music compression takes a lot of advantage that most music is similar in both channels. Natural stereo reverberation becomes completely random with zero correlation between channels. Therefore it's much tougher to compress a reverb tail than the program sometimes, which is why the lower rate encoders gave up and summed it to mono at low levels.

The biggest audible defects at lower rates today aren't obvious things to which you can point a new listener, like clicks or pings. The degradation is a loss of stereo space and image. This becomes obvious on headphones. You'd probably never notice on speakers, and never if you're doing something else while playing music.

128kbs AAC

iTunes 6 uses 128 kbs AAC as default. This is fine. I really have to use my imagination to make myself think I hear any difference between audio coded that way and the original CD.

I could almost hear the ends of reverb tails in one classical recording sum to mono and that was about the only defect.

This default is fine, especially if you have an old iPod which can't handle the variable bit rates which sound better below. With a newer iPod I use:

128 kbs Variable Bit Rate (VBR) AAC : My Choice

For only about a 5% penalty in file size I use variable bit rate encoding for better quality. This lets the coder use more bits when it has to. I set this under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom, and then check "Use Variable Bit Rate Encoding (VBR)." Apple has this pretty well hidden. I leave the rest at default of 128kbs, auto and auto.

VBR sounds better for the same file size. As far as I can see the only reason Apple doesn't default to this is for compatibility with old iPods. Having a new iPod Nano, no problem!

I couldn't hear any defects. 128kbs VBR AAC sounds the same as my CDs. Any defects I heard were accurate reproductions of flaws in the original CDs.

96kbs AAC

96kbs AAC sounds fine for normal use while not paying rapt attention to your music.

It sounds worse than the others listening carefully. It got a little bit swimmy, phasey or flangey if you compared it to the original, and the ends of classical reverb tails would sum to mono if you were paying close attention.

I'd not use this unless you're stuck on an old iPod which can't handle VBR.

96kbs VBR

96kbs VBR sounds better than regular 96kbs. It's not much bigger, maybe 5%, in file size. I can hear a difference between regular and VBR at 96kbs.

I can't hear a difference between 128kbs standard and 128kbs VBR. The reason I chose 128kbs VBR over 128kbs standard is because I can hear the difference at 96kbs. This way I've got some extra, although inaudible, quality improvement over 128kbs standard with almost no file size penalty.

Since 96kbs VBR is about the same size as regular 96kbs I'd suggest 96kbs VBR if you're really trying to cram in as much music as possible. I wouldn't notice anything wrong if I was doing something else while listening, which is how most people listen.

160kbs VBR

I also tried this. It makes bigger files and I couldn't hear any improvement over 128kbs VBR. 128kbs VBR sounded identical to my CDs.

WHAT IS AAC?

AAC is one of many ways to compress audio files. MP3 is another. There are many people with PhDs who spend careers developing and comparing them. Many thanks to these people whose work has given us transparent audio quality at 128kbs.

I didn't go off and try to compare all these systems. It took a day just to compare a few bit rates of AAC. My research was trying to find an optimum setting for getting my wife's CDs into her iPod with the best possible quality at the smallest file size.

I'm a music lover who prefers listening to music over comparing coding schemes.

Encoders get better every year. That's why 128kbs sounds better today than 384kbs used to sound. MP3, actually MPEG-2 layer 3, was OK several years ago and is has established itself as a popular format for illegally copied music. AAC works better today. Better means better sound for the same file size, or smaller files for the same quality. You have to ask yourself if it makes sense to re-encode all your stuff every couple of years for better sound and smaller files. Today I'd skip MP3.

I'm not going to explain AAC itself, sorry. I already explained all this in a paper I delivered some years ago. You can find this and info on all the other compression systems elsewhere in the Internet.

HOW ABOUT THOSE AUDIOPHILES?

For them there is lossless coding which preserves each and every bit of audio data. They would select Apple Lossless Coder under PREFERENCES > ADVANCED > IMPORTING > Import Using & Setting > Custom.

This lossless coder makes big files, about five times as big as 128kbs VBR.

I find 128kbs VBR transparent. If I was really worried about things I can't hear I'd use a higher rate AAC VBR setting, like 160kbs or 256kbs.

The beauty of iPod and iTunes is that you have the flexibility to use any of these schemes, and that it sounds great if you leave everything alone so long as you remember to check "Use Error Correction" as I warned at the top.

Audio has come a long way. Again.

A couple things struck me - I always assumed that the error correction option referred to the internal error correction for the iPod's harddrive - NOT the error correction on your cd-rom drive when you are importing your CD. I'll have to double check wih one of my buddies about this, but I always thought that CDs literally could not work at all without error correction - the beam doesn't focus on a single bit, it focuses on a an area on the disc, and needs to find at least three data points w/in any given area to make a bit.

Secondly, the guy starts off talking about how he had previously "never bothered with these little players or compressed digital audio," but then to buy himself some credibility on the subject asserts that he has worked in exactly that field since the 70s and "delivered a paper" on AAC "years ago" - WTF???

I'm not saying the guy is a charlatan, but you combine the second apparent contradiction with what I believe to be an obvious technical gaffe on CDs and I do have to wonder a little....

What is the guy's name?

Good points, though I am not sure about your theory about the three points, I mean I always thought that the error correction occurs when the three point are not exactly 'aligned' (?), so the processor extapolates the signal from some algoritms. Nowadays it should really matters in term of sound quality expecially when you consider the amount of researches of cd-rom and cd player manufacturers in order to mimimize the effect of error correction in their products. And the same effort of Toshiba Lab to produce software that has the minimum of errors in it.

That's not quite right. Each bit of information on a cd actually corresponds to more than three data points on the cd itself - something like 7 (or 9?) - these datapoints all lie on the solution to a polynomial equation that your cd player is programmed to solve - as I recall it is an order 2 polynomial so that three datapoints imply a solution, but it could be of higher order in which case you would need more than three datapoints - my memory is fuzzy (in general, unfortunately). The point is that the disc has more information than you need to solve the equation (they call this "data redundancy") and the solution itself is your effective "1" or "0". Because you have more information than you need to get the solution, you can lose some of the datapoints (by, say, dropping the disc and scratching it) without causing any problems. This is not something you can turn on and off; it is an essential element of how cds are designed.

[neveronfriday]

WHO THE HELL IS Will Friedwald?

As of today, after a major cleanup, I have 1.57 terrabyte of music in mostly lossless format(s).

Screw that guy.

P.S.: These past weeks I've been seriously considering (that's very seriously) deleting it all because I'm sick and tired of trying to safeguard it against mechanical failure.

Besides, I have about 90% of it on CD, so who cares?

Yep, another nutcase.

P.S.: That size=7 is positively huge!

Edited April 25, 2007 by neveronfriday

[Vimes]

http://www.kenrockwell.com/apple/itunes.htm

(Also, there's more to the article

than was reproduced here - kinda like

128kbps bitrates )

The piece I posted I collected some time back on Digg or something like that. Clearly, whoever posted it there had cut it down. Thanks for the URL for the extended version.

Ii don't necessarily agree with the "engineer" (?) I just thought his points were worthy of interest. I like iPods as nice little toys and use iTunes (now playing, a 128kbps copy of the Beiderbecke/Trumbauer set on Mosaic.) Given the surface noise in the originals, 128 doesn't seem too much of a problem.

BUT the MP3s are playing via an M Audio Firewire Audiophile which, to my ears, does improve the sound. Is that because this device is a pretty good digital to audio converter? The Audiophile, incidentally, is linked to an old Kenwood stack which samples at 44.1kHz using ;large front and smaller rear speakers (KEF and Kenwood respectively).

Sorry if I've unintentionally changed the topic...

[porcy62]

That's not quite right. Each bit of information on a cd actually corresponds to more than three data points on the cd itself - something like 7 (or 9?) - these datapoints all lie on the solution to a polynomial equation that your cd player is programmed to solve - as I recall it is an order 2 polynomial so that three datapoints imply a solution, but it could be of higher order in which case you would need more than three datapoints - my memory is fuzzy (in general, unfortunately). The point is that the disc has more information than you need to solve the equation (they call this "data redundancy") and the solution itself is your effective "1" or "0". Because you have more information than you need to get the solution, you can lose some of the datapoints (by, say, dropping the disc and scratching it) without causing any problems. This is not something you can turn on and off; it is an essential element of how cds are designed.

If so, basically every cd player is only a fast computer with a super eye looking for very small holes turning in a disc, ergo all the quality of the sound relies on the D/A converter, am I right?

So why are cd player manufacturers talking about error correction in cd player? I can't see any possibility of error in your explanation.

Edited April 25, 2007 by porcy62

[porcy62]

http://www.kenrockwell.com/apple/itunes.htm

This article smells funny to me.

I wonder if this guy has ever tried

listening to solo piano music at 128 kbps

(BTW, it is kbps Ken).

R

(Also, there's more to the article

than was reproduced here - kinda like

128kbps bitrates )

Just type 'Ken Rockwell' on google, a lot of funny and controversial stuff about this guy who in a former life worked in audio and in today's reicarnation is a blogger/photographer.

http://www.bahneman.com/liem/blog/article...._Rockwell_Facts

Edited April 25, 2007 by porcy62

[J Larsen]

That's not quite right. Each bit of information on a cd actually corresponds to more than three data points on the cd itself - something like 7 (or 9?) - these datapoints all lie on the solution to a polynomial equation that your cd player is programmed to solve - as I recall it is an order 2 polynomial so that three datapoints imply a solution, but it could be of higher order in which case you would need more than three datapoints - my memory is fuzzy (in general, unfortunately). The point is that the disc has more information than you need to solve the equation (they call this "data redundancy") and the solution itself is your effective "1" or "0". Because you have more information than you need to get the solution, you can lose some of the datapoints (by, say, dropping the disc and scratching it) without causing any problems. This is not something you can turn on and off; it is an essential element of how cds are designed.

If so, basically every cd player is only a fast computer with a super eye looking for very small holes turning in a disc, ergo all the quality of the sound relies on the D/A converter, am I right?

So why are cd player manufacturers talking about error correction in cd player? I can't see any possibility of error in your explanation.

On the first question, I don't think that is quite the full story - there are other electronics that go into the design of the cd player, but I'm not qualified to get into that - my only background in this area is in magnetic memory systems - I picked up my basic knowledge of how cds work by osmosis.

On the second question, you'd really have to point me to some specific examples for me to be able to comment - I don't read up on audio manufacturers' or dealers' claims (mostly because the bullshit factor is enough to make my head explode). However, I can speculate about what they *might* be talking about. Say one bit of audio data is redundantly coded as 7 datapoints on the cd surface, and that you only need three of these to solve your polynomial. Furhter suppose that you damage the disc, so that five of the datapoints have been lost - now you are one short. The cd player could try to interpolate what the bit should be by looking at the previous bit, the next bit, and the two datapoints remaining for the current bit. But this is NOT error correction - it is data interpolation. Error correction is making an error go away and getting the right answer with certainty. Data interpolation is making an educated guess as to what the data probably is. However, I have seen this language abused before, and it wouldn't surprise me if this were the case in the audio literature.

They could possibly also be talking about minimizing tracking problems, but again this would be an abuse of the language.