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Old 9th September 2004, 11:39 AM   #611
ALW is offline ALW  United Kingdom
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Default Missed my point

Quote:
What comes out of the CD player is indeed just digital. The analog comes out of the DAC.
NO!

What comes out of the mechanism (i.e. what is read from the disc) is analogue not digital. It's an analogue signal representing the digital data.

It's not simply a digital system, there's plenty of opportunity for jitter on the disc, the reading process and the conversion of eye-pattern to digital data to affect sound. If this translates to input jitter at the DAC it will be audible.

The fundamental issue is this doesn't matter if you stay in the digital domain, since time is a non-issue, within reason. A cd copied digitally doesn't change the DATA on the disc if the copy is succesful, but it can change the replay process in a CD player as the disc can (will, in most cases with a CD-R drive) have jitter added in the recording phase. Jitter only matter at the D-A process, unless extreme.

Try it, look at the eye pattern in a CDP with mastered and different copied discs - the difference is visible on a 'scope!

A CD player is a streaming system though, in which time is a critical factor.

Click the image to open in full size.

Andy.
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Old 9th September 2004, 11:47 AM   #612
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Hi,

Quote:
CD-Rom uses a different fundamental file structure.
No it does NOT.
A CD-ROM is just a blank writeable disc: Read Only Memory (or Media if you like)

Quote:
The CD Rom file structure writes appx. 20% of the Data with REDUNDANT information that aids arror recovery.
Absolutely NOT.

Quote:
CD Roms remain readable with much worse damage to the Disk than Audio CD's. Try it one day.
Which has nothing to do whatsoever with a damaged data file on a CD.

CD-ROM can be written to using a few standards, these can be mixed on the same CD-ROM but none of those include a single byte of redundant data.
The standards go according to the YellowBook specifications.

Quote:
There is no such mechanism for Red-Book Audio CD. The Error correction is extremely basic.
Digital encoding allows the use of error correction codes, which are necessary to correct errors resulting from the manufacturing process and minor damage or marks which may occur from handling and use.
The result is that the amount of data stored on a CD is nearly four times the data needed to represent the audio only. But this is a small price to pay for a robust format that allows recordings to be played back free of clicks, hiss and other defects associated with analogue media.

Pretty basic perhaps but it's there alright...

So, unless you invented your own standards, I get the impression you're as confused as a barking bird here...

Quote:
You can't be serious asking this question.
Tongue firmly in cheek, Peter....

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Old 9th September 2004, 11:53 AM   #613
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Now we have already had this argument.

There are most definitely read errors on CDs (or even hard drives for that matter) but there is redundant data written so that error correction can detect these mistakes and fix them.

If the error correction fails, you usually get a really colossal mistake. You don't get little errors, since the error correction fixes 100% of the errors.

Since the CD data reading process is designed to cope with dirty disks exposed to the fingerprints or worse, the error correction redundancy is rather high. So it takes a pretty big error to mess it up. If there are any little errors caused by vibration of the disk, they are not not going to affect the actual recomposed digital data NOT ONE SINGLE WHIT, IOTA or SMIGEN.
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Old 9th September 2004, 11:56 AM   #614
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Quote:
Originally posted by geewhizbang
Now we have already had this argument.

There are most definitely read errors on CDs (or even hard drives for that matter) but there is redundant data written so that error correction can detect these mistakes and fix them.

If the error correction fails, you usually get a really colossal mistake. You don't get little errors, since the error correction fixes 100% of the errors.

Since the CD data reading process is designed to cope with dirty disks exposed to the fingerprints or worse, the error correction redundancy is rather high. So it takes a pretty big error to mess it up. If there are any little errors caused by vibration of the disk, they are not not going to affect the actual recomposed digital data NOT ONE SINGLE WHIT, IOTA or SMIGEN.

Clear !

But these vibes migth cause other problem e.g. messing up the low jitter osc.

Well - then that was sorted out !

Shakti, anyone `????


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Old 9th September 2004, 12:04 PM   #615
ALW is offline ALW  United Kingdom
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Default Frank

You're wrong.

If you examine the various CD books you'll see that CD-DA (Audio, Red Book) and CD-ROM (Data, Yellow book) do have a different data format, the latter having more powerful ECC and more precise data addressing.

The physical parameters of CD-ROMs are identical to those defined in the Red Book. However CD-ROM discs differ from CD audio discs in two important ways: -

The data on a CD-ROM disc are divided into sectors containing user data and additional error correction codes.
The data are contained in files and so a file system is needed so that the required files can be accessed easily and quickly.

This does make a difference and is the reason early drives had trouble performing digital audio extraction with any accuracy - the positional information is very low resolution.

CD audio is a streaming, not random-access format.

Andy.
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Old 9th September 2004, 12:33 PM   #616
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Hi,

Quote:
You're wrong.
No I am not wrong.

Quote:
If you examine the various CD books you'll see that CD-DA (Audio) and CD-ROM do have a different data format, the latter having more powerful ECC and more precise data addressing.
Let's get this straight first of all: CD-ROM is not a data standard but the physical medium you can write to:

You could write CD-DA to CD-ROM for instance after which you'd have a CD with DA (digital audio) on it.

If you take that same CD-ROM you could also write DATA to it (files) in a number of formats including ISO 9660, JOLIET, MacIntosh HFS, etc.

What we call a CD-ROM is 9/10 just the medium with data files on it, the same medium with audio on it written as CD-DA standard we'd call an audio CD.
In both cases the discs are nothing more than CD-ROMs just the way it's addressed is different.
In all cases none of the DATA formats contain a single bit of redundant information, CD-DA written formats do.
That ECC is handled differently in both cases is true but in the case of raw data there no extra information actually written to CD-ROM (the medium) that can be used for EC contrary to DA.

Quote:
CD audio is a streaming, not random-access format.
Yes. I never stated anything to the contrary.

To recap the CD-DA Red-Book standard descibes the physical properties of the Compact Disc (CD-ROM) and the digital audio encoding.
Beyond that standard you have the Blue Book which does the same for Enhanced CD, aka CD-Extra.

For info:

Philips Intellectual Property & Standards,
Email: info.licensing@philips.com
URL: www.licensing.philips.com
Fax: +31-40-2732113

Cheers,
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Old 9th September 2004, 01:28 PM   #617
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Default On error correction

CD error correction details

I don't know if this is 100% correct, but it certainly reads like it. To summarize, all CD:s have error correction.

Data CD-s have more correction than audio CD:s, whereas audio CD:s have some degree of error concealment.

Given the playback process (if ECC is properly implemented), it's quite hard to understand how jitter in the bit retrieval can carry through all the way to the DAC. On the other hand, that jitter in the clock that feeds the DAC might cause audible artifacts is not unlikely.

I will refrain from guessing whether Shakti stones or spikes have any effect on the clock jitter level.

Rune
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Old 9th September 2004, 01:31 PM   #618
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Konnichiwa,

Quote:
Originally posted by fdegrove
No it does NOT.
A CD-ROM is just a blank writeable disc: Read Only Memory (or Media if you like)
A CD-Rom is NOT writable.

Further, the Data is encoded on CD's (all of them) in tracks of "Pit's and Land" just as on magnetic Disks it is as north/south magnetisation.

The "File System" is a structure imposed on top of the raw "Pit/Land" or "Nort/South" individual data bit's (the noughts and zeros in effect). This means that a certain specific block of ones and noughts forms a "bedinging of track/file" marker and that then the data is written into the file. Just how it is written and what methodes of revoering errors is implemented depends upon hardware and software implementations and these are are different for CD Rom and Redbook CD.

Quote:
Originally posted by fdegrove
Absolutely NOT.
Absolutely yes, RTFM.

Quote:
Originally posted by fdegrove
Which has nothing to do whatsoever with a damaged data file on a CD.
The File a CD-ROM is damaged if a large enough number of data blocks are not recoverable and if the redundancy data fails to allow correction.

If a sufficient large number of data blocks are unreadable or read incorrectly with an Audio CD the error correction has already failed and must apply error concealement (I lump error corrction and error concealement into one mechanisms as this is how audio CD handels it).

Quote:
Originally posted by fdegrove
CD-ROM can be written to using a few standards,
CD-ROM = CD READ ONLY MEMORY

Meaning it cannot be written at all, you can only press it.

It seems you are erronously refer to the Writable CD-ROM, or more accuratly CD-WORM....

Quote:
Originally posted by fdegrove
these can be mixed on the same CD-ROM but none of those include a single byte of redundant data.
The standards go according to the YellowBook specifications.
I may to re-read, however I remember the standard for DATA Files on CD-Rom to include reduant data.

Quote:
Originally posted by fdegrove
So, unless you invented your own standards, I get the impression you're as confused as a barking bird here...
One of us surely is.

http://www.cdrfaq.org/faq02.html#S2-17

"audio CDs use all 2352 bytes per block for sound samples, while CD-ROMs use only 2048 bytes per block, with most of the rest going to ECC (Error Correcting Code) data."

Hence CD-Rom uses 304 Bytes for every 2048 Bytes data as redudant data, or in other words around 15%. This data is REDUDANT as it is NOT the actual data but data other than that.

Again, RTFM.

Sayonara
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Old 9th September 2004, 01:40 PM   #619
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Quote:
Originally posted by Kuei Yang Wang
Konnichiwa,

http://www.cdrfaq.org/faq02.html#S2-17

"audio CDs use all 2352 bytes per block for sound samples, while CD-ROMs use only 2048 bytes per block, with most of the rest going to ECC (Error Correcting Code) data."
Again, RTFM.
Did you actually bother to read the entire paragraph from which you quoted a part? I suggest you do...

Rune
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Old 9th September 2004, 01:47 PM   #620
ALW is offline ALW  United Kingdom
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Default What do you call it then?

Quote:
Let's get this straight first of all: CD-ROM is not a data standard but the physical medium you can write to
You're arguing silly semantics here but since we've started CD-ROM or CD-ROM XA is covered by the yellow book.

CD or CD-DA is the conventional description for red book discs it also covers CD-G, CD-TEXT, CD-G +MIDI, CD Single, CD Maxi Single, early Karaoke CD, CD Video Single (Extensions to CDDA).

CD-ROM is not the name used for the medium in the red book standard.

Quote:
To recap the CD-DA Red-Book standard descibes the physical properties of the Compact Disc (CD-ROM) and the digital audio encoding.
It covers the physical properties, but does not mention CD-ROM at all in this context.

Anyway, the point was you used your argument to try and repute Kuei's argument about the different formats having different error correction seemingly choosing to mis-interpret his obvious intentions by playing semantics.

Andy.
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