# 4.7Gb DVDÂ±R's limited to 4500Mb?

Whats the deal with DVD Media?

It quite clearly states 4.7Gb (which calculates to 4812Mb).

However, in Nero 6 its limited to 4500Mb (which calculates to 4.39Gb).

try making non multi session disks, i think some space is used wehn making multisessions.

You’re talking about two different measurements, and they’re both EXACTLY the same. For your first calculation, you are incorrectly applying the measurement–4.7 is not multipliable by 1024, since the 4.7 GB number is NOT a binary-derived number.

In the hardware world (including DVD discs, hard drives, zip disks, any other kind of storage), 1 MB=1000 KB. 1 GB=1000 MB. Pretty simple stuff. 4.7 GB here is equal to 4700 MB, and so on and so forth.

The software world, however, chose to make things a little more complicated, wherein 8 bits = 1 byte. Since computers operate in binary code (meaning 1s and 0s), we calculate different classes of size in powers of 2. 2 to the power of 10 is a KiloByte, 2 to the 20th is a MegaByte, 2 to the 30th is a GigaByte. Doing all these conversions, 1 GigaByte (GB) is equal to 1,073,741,824 Bytes.

The difference between the two measurements is a factor of 1073741824/1000000000, or 1.07. 4.7 GB/1.07=roughly 4.39 GB.

This isn’t exactly true. 1024Kytes=1Mbyte etc. This was the original scheme, however hard disk manufacturers decided to exagerate. I can remember the complaints and grumbles when they first did this. Now we accept it. Software Engineers didn’t complicate things, marketing people “simplified” things to their own advantage. I know I’m a marketing person who use to be a software person (and I used to be a hardware engineer).

it was started by hard drive manufacturers to overinflate the storage sizes. funny thing is that while hard drive manufacturers went with 1Mb = 1000Kb, CD specs use 1Mb = 1024Kb, but DVD specs use 1Mb = 1000Kb. it’s a pain.

but technically, hard drive manufacturers can do this, because the standard kilo, mega, giga, DO mean 1000, 1000,000, and 1,000,000,000. personally, i like to use a small kb for 1000 bytes and Kb for 1024 bytes, but there is a standard now which defines this (although i hate it). kilo = 1000 bytes, but kibi = 1024. i’m not going to start typing KiB instead of Kb, but oh well…

http://physics.nist.gov/cuu/Units/binary.html

kigi, mebi, gibi, tibi? yuck.

I understand all the details regarding byte conversion… I just assumed that since it is a standard format it would follow the same system.

But I will contest the “hardware = 1000” and “software = 1024”.

As you can see my drive is a 160Gb (as stated on the drive) and under the hardware conversion you’ve stated, it should only be 160,000,000,000 bytes. And after formatting it becomes 152Gb, which as i’m sure you all know the ‘missing’ space is used by the filing system. But again using the hardware standard should only be 152,000,000,000 bytes. As you can see from the screenshot, its not!

As far as I have learnt, all measurements using BYTES are converted using 1024 - be it memory or hard disks or floppy disks. The only exception to this rule is BITS which are converted using 1000.

Anyway, the official maximum is 4500 MegaBYTES then? Meaning 4,718,592,000 bytes?

as stated above its just a method for drive manufacturers to inflate their drive size

its not a hardware vs software thing. Its a marketing thing. Any real tech will tell you that.

1 Kilobyte= 2^10 bytes
1 Megabyte = 2^20 bytes
1 Gigabyte = 2^30 bytes
1 Terrabyte = 2 ^40 bytes

But then…

Remember video game manufacturers quoting things in MegaBITS!!!
(a bit is 1/8th of a byte. This conversion is made because of the old old coinage where 2 bits was otherwise known as 25 cents which was 1/4 of a dollar, hence a bit was 1/8th, or so ive heard thats where it comes from)

Ahhh the evils of marketting

i agree. how else can you explain that mega = 2^20 regarding CD storage, yet mega = 10^6 regarding DVD storage…