#Basic CD-Rom info
3 messages in this thread
We are the process of creating a large data-base which we later intend to
produce on CD-Rom. Before we go ahead and demonstrate our prototype I
would appreciate answers to the following:
1. What is the exact size of files that one can copy onto a CD-rom.
I have seen quotes that range from 540 to 680 MB ?!?
Is there one static number ?
Thanks in advance !
Jeff Abraham
jeff,
As the technology has evolved, the manufacturers have found that they can
get more data on the cdrom than what was originally (and conservatively)
specified. The capacities are normally specified in seconds where each
seconds data area can store 153.6 k of error corrected data. Therefore a
60 minute disc can store ~553 meg.
corresponding to this a 74 minute disc can store ~682 meg.
From this number you need to subtract at least 4 seconds for ISO and
mastering overhead.
If you want to be very conservative you will want to assume 63 minutes for
your data since I have heard that some of the first generation drives have
problems reading the 74 minute discs.
The 63 and 74 minute discs are what are available as one-off blanks which
is the reason I've used these numbers. I think that some of the mastering
houses may be able to get more than 74 minutes, but I'll let them respond.
Glen Chapman – Online Computer Systems
Jeff,
Unfortunately there does not seem to be one static number. As I
understand it, it depends on the mastering equipment, and if you're using a
one-off the blank you stick in.
Up to 680 meg can be read on all standard drives, but there is some
equipment out there that can only write 512meg. There is also equipment
that can write 700 and some meg, but not all drives can read it.
FWIW, the 680 meg figure is the one that corresponds to the 74
minute audio CD standard.
Frank