Why don't they swich from CDA to "computer like" files on the CDs?

Fun Fan

Standard Member
Joined
Nov 30, 2008
Messages
31
Reaction score
0
Points
7
Hello everyone,
I am new here and I might ask a question which had been answered before.
If so, excuse me and give me the link to the answer.

Here is the question:
As there are reading errors when playing a CD, why don't they encrypt the file the same way they do on the computers?

I mean, on the comp you can't read the file with errors. Either you read the entire file or the file is damaged and, most probably, you don't read it at all.
It would be very easy to code the files in the same manner on the CD and you will eliminate at least the mechanical errors in reading.

This way you won't be needing a very sophisticate, accurate and expensive transport, having to deal only with the DAC problems.

And I think the cheapest electronics could be design to read such (new kind of) a file.
 
The real problem with CD's is the fact that the data is in a continous spiral that starts at the inner disc and runs to the outside of the disc.

No matter what type of data is on the disc , the laser must accurately track the data spiral at all times meaning no matter what format the data on the disc takes the transport and its ability to track that spiral will always be a cause for errors.

Encrypting the data so that it wont play unless uncorrupted would only make many CD drives unable to play anything.

Software like EAC can be used to accurately grab the data off a disc and make a file that will always play without errors. But as long as mechanical players are used to read CD's then errors and error masking will always be an issue.

I suspect in future we may see albums and such released on a format such as SD memory cards , meaning no lasers tracking rotating discs and no moving parts and as such , no errors.
 
I still don't get it.
It would be so easy.
One CD-rom, a file with verification code (THIS WOULD DO THE TRICK - Smaler sections of the song and THE VERIFICATION CODE), internal memory buffer and, voila, you have no reading error!

Thank you again anyway.
 
Last edited:
I still don't get it.
It would be so easy.
One CD-rom, a file with verification code, internal memory buffer and, voila, you have no reading error!

Regardless of whats on the CD , the mechanics of reading the CD are the same, the laser must accurately track the spiral.

Unless you have an excellent transport , there will be errors , so for instance , if you take your current CD player , put the file you describe on it , then try to read it , the chances are it couldnt , because you would have made the content fault intolerant. It would never play ....

The key to " getting it " is to start with the fact that no matter whats on the disc , the transport must accurately track the data spiral on the disc , if you make that data or content playable only on the condition that the data is 100% intact , then you are insisting that your transport makes a perfect read every time or nothing gets played. That would mean that every player from the cheapest to the most expensive , must have a perfect transport , and that is not possible.

The only thing that makes say , a £20 player possible is cheap parts , if you want players available for this price then it must be accepted that some quality has been sacrificed to achieve this affordability , error masking routines and such make the output OK , and those who cant afford high end have an acceptable compromise. Should files like you describe be put on CD instead of the standard red book audio stream , then only perfect transports could be used , meaning only high end players would exist , therefore those with smaller budgets could not have a CD player.... and so on.
 
Last edited:
You got me wrong.
I am not a native english speaker so I might not explain very well.

I don’t want to write the files as they are now.
I want to write them as we write the data CDs.
If you put a wave file (for example, but the format is unimportant) on a disk, even the cheapest CD-rom will be able to read it. And not losing a bit.
So, if the (wave) file has a good recording on it you will be able to read with no losses that recording.
You will be left with the problem of “playing” that file, which is a problem of converting the information into analog audio signal.
But the file will be always read completely and with no errors.
All you have to do is to make the new CD player able to read the new files.
So, in fact, the new CD player will be an MP3 Player, a Wave Player or Whatever Player.
The expensive CD players will be useless. (As in the case they put the new recordings on memory sticks. But they have to put music on CDs with the new files on them.)

Did I make myself clearer this time?

And, most important,
I Hope I am not bothering you!
 
I understand what you are saying - a recording/playback method with proper error correction would, undoubtedly, be superior to the current .cda "red book" format.
If they were writing the standards now, I'm sure they would do it as you suggested.

Thing is, it takes a fair amount of computing power to buffer, correct any errors by re-reading or parity checking, re-clock and output the perfect data stream. When CDs were first released, this just wasn't possible. As far as I remember, CD audio was out before computer optical drives were available.

To re-write the CD standard now is pointless, as it's an old-fashioned method of storing/distributing/playing music. If it wasn't so cheap to use, it would have died out by now.

Since it's possible to rip a CD on a computer, creating a near-perfect copy which can be played back directly from the hard disk, HDD or network media players already provide "perfect" playback for those that want it. I can see high-end CD players dying out in the next couple of years.

99% of the population are perfectly happy to listen to 128kb/s mp3s, preferring it to the existing CD audio format. There's practically no market for a better CD format.
 
Thank you both!
I will start the quest for a good and complex DAC.
I am not interested in a good CD player anymore.
(Although this is not a very “HiFi” attitude!)

Any suggestions for a good DAC?
With optical and USB inputs!
 
No answer any longer...
I hope I didn't bother, upset or offend anybody!
Apologize if I did.
 
I don't think you've upset anyone.

I've read about DACs with 2 inputs, and there are DACs with a USB input. Not heard any of them, so can't make a recommendation.
If you need more than 2 inputs, an AV amp might be the way to go. Multiple digital inputs - nothing to stop you using a 7.1 amp in stereo mode, or as a stereo pre-amp.

Might be worth starting a new post to ask about DACs. Make sure you list all your requirements, and what sources you want to play through it.
 
Last edited:
Oh, thanks!

I think I want to take music files (wave or another quality encryption) from computer (or other support) and to turn them into analogical signal trough a very good converter.
That is why (I think) I want a USB input.
Or do you think I should make the conversion in the comp using a "soft" DAC? (Windows media player, Sony SondForge etc.)

I am using a Yarland FV 34 CIII.
I like it so much that I also both the Pro 88SE.
So I think a 5.1; 7.1; n.1 is not what I want.

I want a good source but I am not wiling to buy Linn CD12 for that.
As you said, CD is loosing ground. As long as you put the music on a different digital support, you will play it better than from the most expensive CD player. (Where do you take the files from to put them on the comp is another (yet unsolved) issue!)

Finally, what would be your advice?
 
For the best sound quality, I'd avoid using a PC as the source. Get a dedicated media player. Windows computers are better than using something like an iPod, but all that electrical noise inside a computer can do nasty thing even to a digital signal. You also need to bypass the Windows mixer, using dedicated audio drivers. If you must use a computer, get a soundcard with an optical output and use that to feed an external DAC.

After an extensive demo, I went for a PixelMagic HD-MB200 media player. This device (now discontinued) can play from it's own HDD, from an external HDD, or from a network. Has a pretty good DAC built in.

Other options are a Squeezebox, Transporter or Sonos. Many more to choose from.
 
There are a lot of problems in your questions and a range of serious misunderstandings.

1) You've completely confused encryption and encoding. Encryption is about security - making sure that only those with the decryption key can access the content. DVD, Bluray and HDMI use encryption as a copy protection mechanism (not all that successfully in the case of DVD). Encoding is a means of representing a source in some way that is equivalent to the original, but not the same as (e.g. bit reordering and addition of extra bits to prevent CD damage from making sections unrecoverable).

2) You are assuming that CDA has no redundancy and is therefore more likely to be subject to read errors. The reality is very different with the audio content making up less than one third of the data. Wikipedia's explanation is quite clear:
The smallest entity in a CD is called a frame, which consists of 33 bytes and contains six complete 16-bit stereo samples (two bytes × two channels × six samples: equals 24 bytes). The other nine bytes consist of eight CIRC error-correction bytes and one subcode byte, used for control and display. Each byte is translated into a 14-bit word using eight-to-fourteen modulation, which alternates with three-bit merging words. In total there are 33 × (14 + 3) = 561 bits. A 27-bit unique synchronization word is added, so that the number of bits in a frame totals 588 (of which only 192 bits are music).

3) You are assuming that CD-Audio has no or limited error detection and correction. As already explained in the answer to 2), this is not the case: CD-Audio has extensive error correction and detection, as well as interpolation in the case of very serious errors (e.g. severe scratching or scuffing).

4) You are assuming that data CDs are more reliable than audio CD. Although there is additional error detection, they disk are not inherently more reliable, they merely refuse to read when the errors reach a certain level of severity . Audio CDs have an additional tolerance with error interpolation, making the format a better option for music.

The CD-Audio format is a much better format for audio than the CD-Data format. However, using data formats enables the encoding of lower quality, lossily compressed audio recordings, thus yielding longer player times at the expense of quality. Most DVD players and many CD players can play such disks.
 
To Mark
Thank you for pointing out some of the errors.
1) encryption and encoding = I know the difference. It is the use of english that betrayed me.
I was referring to the format in which you write the information on the support. I was referring to type of file: wave, mp3, wma etc.

2) and 3) As you said CD-Audio has extensive error correction and detection, as well as interpolation in the case of very serious errors. But I don't need the CORRECTION!
I am pretty sure that I wouldn't be able to hear the difference, but just knowing that there is something correcting – which equals modifying – the information, makes me feel uncomfortable.
4) I am not interested - in this case - in the reliability. I am interested only in the ABILITY to READ AGAIN and AGAIN the SAME information I put on the support. And with no errors, corrections etc. In a word, with no modifications.

Finally, I am also not interested in compression. I am not interested in storage space or playback time or anything that implies lowering the quality of the recording.

To clockworks:
Pretty good DAC means “pretty damn good”?
Or does it mean “acceptable”, “better than one would expect” etc?

Now,
To put it better and in better english (I hope):
I want to have ALL the information on the support and the means TO READ ALL THAT information.
EACH time I play it!

This happens with all the computer files! The comp reads all the information on its files without losing a bit and it does so every time you access that file.
Therefore, I thought to put music on such a file.

The whole Idea is:
Presuming I have a file, a computer format file, on a support.
(HDD, DVD, CD etc.)
(How good it is the recording on it is another issue – presume it is the best).

This file is a digital file. (WAV, lossless mp3, WMA, etc.)
What is the best way I should feed it to my “China Made All Tube Amplifier”?

After you stopped laughing or after you stopped being angry that I made all this fuss just for some chinese rubbish, please, give me the best ideas you can come-up with.
 
Last edited:
By "pretty good DAC" I mean that it's very easy to tell the difference compared to using a laptop optical output into the on-board DAC of an Arcam Solo amplifier. The media player was miles better.
It sounded almost as good as a midrange (£700) CD player - can't remember which model CD player, but it was the best one the dealer had in this price range. We were using it as the "control" source in our tests. There were some slight differences, but nothing you would notice unless you were comparing the two (CDP and Pixel Magic) back to back.

Adding an an external DAC (Flying Cow) improved the media player. We both thought that it was now noticeably better than the CDP.

In my opinion, if you get a PixelMagic HD-MB200, you won't be disappointed with the sound quality. Note that they also made a HD-MB100, which had a lower spec DAC.


If you want "perfect" playback each time, a computer file-based HDD system is probably the only way to do it, either a HDD media player (self contained), a network media player (needs a PC or a network attached storage device running) or a PC.

I'd forget about the PC, as I don't believe you'll ever get real hi-fi audio using a computer as a playback device.

That leaves either a HDD media player (like the HD-MB200) or a network player.

It's really a case of what features and functions you want. There's no real difference in the ultimate sound sound quality between the two types of device. They both play the same files. Some devices are better than others, but that's down to the device, not how it gets the files.

Probably the biggest difference between self-contained and network players is what other equipment you need running to use them. A network player obviously needs a server of some kind, on a wired or wireless network. They usually have a small display built in to allow you to find your tracks.

The only drawback with my PixelMagic player is that it doesn't have a display - you need to connect a TV or computer monitor to see your tracks or playlists. As a plus, it does something that network players don't normally do - it plays back HD video (DVD rips, etc.).

As for file formats, stick with wav or flac.

I understand that some of these Chinese tube amps are very good. I don't think anyone should knock Chinese goods - some of it is up there with the best. The Swiss are getting very worried about Chinese watches!
 
“The Swiss are getting very worried about Chinese watches!”
Touché Monsieur Pussycat!

I hope Mark has enough sense of humor!
I am grateful to him for his remarks, but I couldn't stop myself from smiling at clockwork's line.

Back to (a little more) serious stuff...

What I'm left with ‘till now:
I need
- a HDD player (Pixel Magic HD-MB200 or better)
and, perhaps,
- an external DAC (Flying Cow or better)

And, off course, a good amp and loudspeakers.

Regarding the files format, I would have stuck to uncompressed files anyway.

The source of good wav files is a problem still to be solved.

Perhaps ripping from CD's.
I tried a few times, a few programs and a few (uncompressed) formats and I get the same length of the file.
Which seams a good start.
I ripped with Media Player and get xKb.
I ripped with SoundForge and saved as windows wav file and got the same xkb long file.
I ripped with SoundForge and saved as Scott Studio wav file and, again, an xkb long file.

As far as the DVD-ram in the comp should be a pretty accurate CD player, do you think this could be a good source?
(I'll try again after some time to see if what I read today -and ripped- I'll read again tomorrow. -from the CD!)

The nice part is that “Good times, bad times” from “the very best of Led Zeppelin” 2 CD box 0 75678 36195 1, CD no 7567-83619-2 vol1 Atlantic...
...produced a bigger (longer) file than...
...the same song from Led Zeppelin vol IV CD no 7567-82632-2, also from Atlantic.
Both CDs where digitally remastered from the same original tapes, bla-bla, bla-bla...

However, this is an entirely and completely other issue!
 
Are you Swiss?

I've been collecting watches for a few years. I also repair watches for my own satisfaction, and I repair clocks as a part time business.
When I started, I wouldn't dream of buying Chinese - their clocks were junk, their watches mostly cheap and nasty fakes.

Recently I've bought a couple of Chinese automatics. For the price, the quality is now very good. You can buy a complete watch for much less than the price of a bare ETA movement. Not sure about long term reliability.
The prices of Swiss parts have also increased dramatically. 3 years ago, I could buy an ETA 2824-2 movement for £30 trade, now the price is over £120.

I've heard that ETA are now sourcing components for their low-end movements from China.

Back on topic. I rip from CD to wav. The important thing for me is to set the maximum read rate a lot lower than the maximum rate of the hardware. I normally go for 8x to 12x. Also set the software to retry if there are still reading errors, rather than using error correction. This should give you a perfect copy.
 
2) and 3) As you said CD-Audio has extensive error correction and detection, as well as interpolation in the case of very serious errors. But I don't need the CORRECTION!
You most definitely do need error detection and correction. You need it for data CDs in order to be able to read your MP3 or WAV. Without it very few disks (if any) would ever be readable. CDs (all formats) are designed for errors and CDs (all formats) have errors - this is a simple fact of life. Dealing with and resolving errors is therefore a core feature of the lowest levels of the CD, DVD and Bluray formats (it is not a part of the CD-Audio spec). What you're claiming is that you don't "need" interpolation - you'd prefer to be forced to ditch a bad disk than have it interpolate - because that's the only alternative. This is anyway up to you: If the error correction lamp on the player shows or you can hear (severe) interpolation, you may of course replace the duff disk.

I am pretty sure that I wouldn't be able to hear the difference, but just knowing that there is something correcting – which equals modifying – the information, makes me feel uncomfortable.
You are still missing the point. Correction is a part of the architecture - a CD (all formats) stores "way too many" bits so that when one bit can't be read, another can be used to reconstruct it perfectly - without error. As I stated above, without this, very few CDs (regardless of format or content) could be read. Error correction cannot be "determined" since the resultant bit stream is 100% correct by definition - that's the definition of the word correction. Not only can't you determine it, you don't even know it's happening.

Interpolation occurs only when the CD can no longer be read without errors - when so many bits are corrupt that error correction can no longer recover the original bits. Using a data format CD means that the drive gives a bad block error (it fails subsequent checks) and therefore it fails to read the file. An audio CD drive will apply interpolation, but only in the case that the CD is "that bad" that it is anyway partially unreadable.

4) I am not interested - in this case - in the reliability. I am interested only in the ABILITY to READ AGAIN and AGAIN the SAME information I put on the support. And with no errors, corrections etc. In a word, with no modifications.
As I said, you are very, very confused about what you want and what you have and what you need and what an error is and what correction is. You also seem to have serious problems with English words such as "reliability", "ability", "read", "same", "error", "correction" and "modification".

To reiterate, unless a CD is badly damaged (or your drive is bust) you get 100% accuracy 100% of the time regardless of the specific format. When it becomes severely damaged, or covered in jam, an audio CD will interpolate (until it can no longer track), a data CD will need replacing (or cleaning). Proper handling and storage of a CD is therefore the key to success, but not any of the things you incorrectly suggest (they do absolutely nothing).

I want to have ALL the information on the support and the means TO READ ALL THAT information.
EACH time I play it!
This happens with all the computer files! The comp reads all the information on its files without losing a bit and it does so every time you access that file.
Therefore, I thought to put music on such a file.
No, this is not what happens with computer files, it's what happens with the CD / HDD / DVD / USB stick / whatever. The PC and the file format have absolutely nothing to do with this. All the PC does is yell when the media can not be read (after application of error correction), forcing replacement of the carrier, whatever the carrier is. That's also why computers meeting data access reliability demands have both redundant disks (RAID - single media failure) and backups (greater disaster). They also use EEC memory (to correct memory errors).

.. lossless mp3 ...
No such thing. MP3 is a lossy compression algorithm by definition of the format. IOW, if the compression scheme is lossless, it cannot be MP3.

[I wear Japanese watches.]
 
Last edited:
"To reiterate, unless a CD is badly damaged (or your drive is bust) you get 100% accuracy 100% of the time"

This is what I thought about CDs until some years ago.

And then I started reading about "reading errors of the CD players"! (Because of speed erros of the transport mechanism or other sources.)

Now what should I understand?
Do you have reading errors or do you get 100% accuracy 100% of the time?

[ I see, japanese watches! But what car do you drive?]
 
Last edited:
I currently drive a Japanese car, after many years of Ford or Vauxhall. It's a company lease car. I chose it because it costs me less per month than the equivalent Ford or Vauxhall.

Of the 100+ watches I own, the vast majority are Swiss.


On topic, I think we're getting a bit hung up on semantics.
The basic facts are, as I understand it, that a computer can do a better job of extracting and correcting the digital information from an audio CD than a CD player can. The CDP suffers because it is playing in real time. Not 100% true, because it buffers the information, but the buffer is small compared to a computer when ripping to a file.

A digital media player can read a file and present it to the DAC more cost-effectively than a CDP. That is, you can get the same "quality" for less money with a media player.

An external DAC allows you to choose the sound quality you want, and how much you spend.

If you factor in the cost of the computer, a CDP might be cheaper. Since you already own the computer, a media player is often cheaper for the equivalent sound quality.

There are bound to be exceptions - some over-priced media players or bargain disk players that just happen to have better sound quality than their price would suggest.

A media player wins on flexibility. A CDP wins on ease of use for playing one CD.
 
The basic facts are, as I understand it, that a computer can do a better job of extracting and correcting the digital information from an audio CD than a CD player can. The CDP suffers because it is playing in real time. Not 100% true, because it buffers the information, but the buffer is small compared to a computer when ripping to a file.
The "basic facts" as you understand them are incorrect; your understanding is incomplete.

The PC does not do a better job of reading a CD, any more than a data CD is more (or less) reliable than an audio CD. The sîmple facts are that unless the disk is badly damaged (or the CDP or PC drive needs fixing) both retrieve the data with 100% accuracy.

I drive a German car. However my wife is Swiss - proving conclusively to me that the most important and best things in life are Swiss :).
 
The "basic facts" as you understand them are incorrect; your understanding is incomplete.

The PC does not do a better job of reading a CD, any more than a data CD is more (or less) reliable than an audio CD. The sîmple facts are that unless the disk is badly damaged (or the CDP or PC drive needs fixing) both retrieve the data with 100% accuracy.

I drive a German car. However my wife is Swiss - proving conclusively to me that the most important and best things in life are Swiss :).

If this is the case, surely all CD transports would sound the same? Note that I'm only referring to the digital domain.
A CD transport may manage to retrieve the data (or reconstruct it), but will it present it at the right time? Since the information is digital, the only things that can negatively affect the "sound quality" are the loss of data or timing errors.
 
The PC does not do a better job of reading a CD, any more than a data CD is more (or less) reliable than an audio CD. The sîmple facts are that unless the disk is badly damaged (or the CDP or PC drive needs fixing) both retrieve the data with 100% accuracy.

This is not the case and can easily be proven.
The simple fact is that most affordable CD players do not produce the same bitstream at the output.

Given the same CD , some test equipment , and a variety of CD players it can be shown that most of them will produce a different digital output.
Only on highly accurate transports do players produce the bitstream intended to come from the CD.
And those players are not cheap.
 
Last edited:
To Mark
If what you obtain from a CD is 100% correct and the same every time, what “reading errors” are the specialists talking about?
As Andy asked: Why the CD players do not produce the same bit stream at the output?

And as clockworks pointed-out: we are only referring to the digital domain.


To clockworks
I am not Swiss, but I also have a japanese car, I still have some old Swiss and Sovietic watches (nothing important, and nothing in working condition anymore except some electrical Swatch) and my wife just works for Swiss.
 
If what you obtain from a CD is 100% correct and the same every time, what “reading errors” are the specialists talking about?
I have no idea what "these specialists" are talking about, only that they are talking nonsense.
As Andy asked: Why the CD players do not produce the same bit stream at the output?
Andy's question is like "when did you stop beating your wife?" It makes an invalid assumption and then asks why. Unless broken, CD players do produce the bit stream on the CD at the output. If broken a repair is in order. If Andy says "it can be proven", he's going to have to do so - it should be amusing to watch while he flounders in the attempt.

Clockwork's response may indicate the source of the confusion:
If this is the case, surely all CD transports would sound the same? Note that I'm only referring to the digital domain.
No, this is not correct, but the reasons are unrelated to error correction / "reading errors".
A CD transport may manage to retrieve the data (or reconstruct it), but will it present it at the right time? Since the information is digital, the only things that can negatively affect the "sound quality" are the loss of data or timing errors.
So far your (Fun Fan) posts have referred to data errors - which do not occur. Clockwork throws in "right time" and "timing errors": I think he's trying to say jitter. The level of jitter from various "transports" for various media (CD, HDD, your iPod) can and does differ.

The transport must not only read the bits, it must also present them at the correct (44.1kHz) point in time to the DAC. If the clock is less than perfect, a bit can be presented slightly early / late, thus leading to distortion, and this obviously affects the sound. Jitter reduction is a complex subject, but it is not caused by the media or the mechanics of the transport. For further reading, here's a 15 year old article on the subject: Stereophile: A Transport of Delight: CD Transport Jitter.

To return to the original question
As there are reading errors when playing a CD, why don't they encrypt the file the same way they do on the computers? ... etc ...
jitter effects are not read errors, computers do not do a better job of jitter reduction (in fact, most do a much worse job) and using a data format instead of an audio format doesn't reduce jitter - in fact, since it requires external PLL clock recovery, it probably makes things worse.
 
Last edited:
Yes, I was avoiding saying jitter, but that's what I meant.
Are you saying that ALL the perceived differences in sound quality are down to timing/jitter problems, or is there something else going on?
There can be huge differences in sound quality between different players using the same source file into the same DAC, amp and speakers. I don't think that anyone whose done comparisons could dispute that.

Just to clarify, when I use the term "CD transport", I'm using it to mean the replay device in it's entirety up to the DAC stage, not just the spindle, laser mech and associated control circuits. I'm including the buffer, clock, logic and digital output stages.

On the subject of computer CD drives used to extract cda to wav, I appreciate that these will be inferior to a proper CDP. Thing is, does it actually make any difference to the file that's created? I've no idea about the file structure of wav. Does the "quality" of the file depend on the hardware used to create it, or just on the software used for ripping?
Note that I'm only talking about creating a wav file on a computer, not playing it back.

If I create 2 wav files on 2 different computers, using the same CD and the same ripping software, then transfer those files to the same HDD media player, can there possibly be any difference in sound quality?
 

The latest video from AVForums

Is 4K Blu-ray Worth It?
Subscribe to our YouTube channel
Back
Top Bottom