Question about CD-R's (1 Viewer)

[Greg Johnson]

OK, I hearby nominate myself for stupid question of the day but I have to ask.

When copying a redbook CD using Roxio CD copier software. Is the copy or CD-R an exact bit for bit digital copy that will sound exactly the same as the original.

Greg

 

[Ted Lee]

i've always wondered that myself. i think it may depend on the app? i know a lot of people here like Exact Audio Copy - which i think is bit-for-bit. not sure about roxio though...although that's what i use. i probably couldn't tell the difference anyway.

....am thinking of copying some of my collection and selling the originals on Ebay.

whoop! whoop! red alert!

 

[Tony-B]

I've never burned a CD before and am thinking of copying some of my collection and selling the originals on Ebay.

Here comes the RIAA police!

 

[Grant B]

uuummmm you can legally copy cds for your own use. i make a copy with text for my megachangers and keep the original for the car

 

[Greg Johnson]

The way I understand the copyright laws I can make a copy for my own use. I don't believe selling the original CD that I purchased is illegal. Now if I were to sell the copy that's another story.
I still would like to know the answer to my question.

 

[Cary_H]

I believe that once you parted with the original, the copy in your possession would be deemed illegal.

 

[Ted Lee]

uuummmm you can legally copy cds for your own use. i make a copy with text for my megachangers and keep the original for the car

of course that's true. i do the same thing.

however, the point is greg wants to *sell* the original. at that point, any copies he owns would be illegal.

anyway, anyone know the answer to his original question? i'm still curious.

 

[Thomas Newton]

anyway, anyone know the answer to his original question? i'm still curious.

Whether it's an exact bit-for-bit copy of what the computer can read from the CD-ROM drive would depend on the software. E.g., track-by-track burning or deletion of subcode data might cause some bits to be different even if the stereo audio bits for each track were an exact copy of what the computer read.

There's a separate issue in that the computer might not be able to read an exact copy of the bits on the CD. The CD-Audio format is not known for near-100% odds of perfect recovery of bits; the idea is to feed a constant-rate stream of bits to the player, and if a bit is corrupted, why the player can just interpolate a fix, or play the bad bit as-is. CD-ROM format devotes some of the disk space to more error detection/correction overhead precisely because such errors are not tolerable when reading things like .EXE files.

On the writing side, the CD burner may introduce additional errors. Some people have run into problems where audio CDs burned at high speed have "clicks" when played back on home stereos. The problems often go away when burning at low speed, suggesting a mechanical cause (such as vibration of the disc or the write laser).

So it's sort-of bit-for-bit, but there are opportunities for things to go wrong -- sometimes with audible results, sometimes not.

 

[Wes]

I have Nero express software, If I use the "Copy Entire Disc" selection at say 4kbs copy speed would I be losing quality? I just assumed it would be perfect!

Wes

 

[John Watson]

Wes, my guess is that it will be as perfect as we need it to be.

If you have been using Nero Express, I'm curious whether you've figured out a couple of things tho, that have me puzzled.

I asked these questions a few months ago, but no answers at that time.

http://www.hometheaterforum.com/htfo...hreadid=144066

 

[Dan Stone]

Post the original question at the Steve Hoffman forum (www.stevehoffman.tv/forums) and you will almost surely get an answer from one of the people there who are extremely knowledgeable regarding CD recording software.

 

[MarkHastings]

On the writing side, the CD burner may introduce additional errors. Some people have run into problems where audio CDs burned at high speed have "clicks" when played back on home stereos. The problems often go away when burning at low speed, suggesting a mechanical cause (such as vibration of the disc or the write laser).

Definitely the quality of the burn is a bigger issue than if it's a direct digital copy or not.

I amlost wonder if burning a copy is maybe even better because you are burning the grooves, hence making them deeper over the original CD which has been stamped.

 

[Lee Scoggins]

Is the copy or CD-R an exact bit for bit digital copy that will sound exactly the same as the original.

Even with the same bits, you can easily (and likely) introduce jitter which is time-based distortion. We are having a technical discussion about this in the audio/video forum that provides background.

The key thing to remember is that the CD has "time code" as well as ones and zeros encoded on it. It the time code shifts then the playback will sound less precise and smeary. There are devices that measure jitter down to the picosecond and some of us believe that that level is audible and others believe that hundreds of nanoseconds is audible.

Different CD burners introduce different levels of jitter, there is no perfect jitter device, the key is to make it as low as possible.

In summary, "bits are bit only when they show up at the right time".

I am working on a jitter test CD and will make it available to HTF in a month or less.

www.stereophile.com has some jitter metrics based on the Miller Audio device.

Also, Bob Katz has found that there is less jitter when the CD burner writes at a 1X speed.

I hope that's helpful.

 

[Wes]

John, nope, I'm pretty much a newbie to this burning stuff. I'm lucky they give the Copy Entire CD option as I would be lost other wise!

Wes