What exactly do the CD speeds mean?



A friend of mine and I were comparing our technical perceptions of what exactly the speed desgnations mean on the CDs and there respective players.

I just purchased the 24x10x40x Lacie burner with 100 16x CDs. I understand the device can write at 24x, multisession at 10x and read at 40x.

The relation to the CDs designation is the unknown peice. Can a 16x CD be read dependably from a 1x reader? I burned and verified with writes at 16x and 8x of the same data on two identical CDs. Is it coincedence that fewer readers were able to read the 16x CD?

Is the 16x CD any different when written at a lower speed? I imagine the CD may choke on a higher write speed.

What is the physical difference between the CDs speeds and what exactly is is the multiplication factor?

Thank You


Barking at the moon.
the CD-ROM speed has to do more with the data transfer rate from the disk to your computer. each 'x' is a factor of 150 kb/s. 2X drives read at 300 kb/s, 3X drives read at 450 kb/s, etc, etc.

As for you question about the burning speeds, there theoretically shouldn't be any difference between a disc burned at 8x and the same thing burned at 16x. Although this will depend on your drive and software's ability to prevent under-burning and/or data rate 'hiccups'.

It's just one of those little known facts that the slower your burn your disc, the more accurate the burn will be because your drive and computer don't have to keep catching up to eachother. (another factor can be the actual CD-R discs that you're using .. obviously)

BTW, this would probably be better in the Hardware forum. ;)

Red Phoenix

The original CD drives maxed out the amount of data they could read at 150 kilobytes per second. Consequently, they were called "1x" after CD drives that could do it at 300 kilobytes per second came out (which were, strangely enough, called "2x").

The burning of a CD is supposed to be dependable no matter what speed it's done at. So a CD that is burnt at 16x can be read by a 1x, although it will take 16 times as long in the total time it would take to read it completely compared to the time it took to write it.

However, certain CDs are only dependably burnt at certain speeds (because of how they were made), and so if you try to burn a CD that is only dependable at 8x with a 16x burner at full speed, then you'll likely end up with a ruined CD. That's where the speeds on the CD itself comes in. It's only important for the burning of the CD, not for the actual usage of it.

Finally, you should note that if you actually tried to, say, play a movie on a 1x CD drive, you would probably be unable to do it, just because the CD drive itself would be too slow to read the movie off the CD in real time.

Hope this helps.