The capacity of a DVD

[parsifal]

Well, I was not sure where to post this topic... perhaps this is more flame than support related topic ... But hopefully it fits among others.

I am new to the whole DVD-burning world. I went shopping and bought a box of five Fujifilm's supposed-to-be-standard-DVDs, size 4.7GB. I got home, inserted one of my new DVD+R-discs and got terrified: the size of the DVD was actually 4483MB.

Let's see if I can calculate this one correctly...

1024B equals 1kB.
1024kB equals 1MB.
1024MB equals 1GB.

Therefore 1GB equals 1024*1024*1024 B = 1073741824B.
That multiplied with the factor 4.7 = 4.7 *1073741824B = 5046586572.8B

And that divided with 1024 to get the size in kilobytes:
5046586572.8B / 1024 = 4928307.2kB
And megabytes:
4928307.2kB / 1024 = 4812.8MB.

4812.8MB - 4483MB = 329.8MB

Of the 4.7GB disc this is: 329.8MB / 4812.8MB * 100 = (approximately) 6.85%

It is a big difference.

If any of the following is true, jump to the end of my post :
- I am in a dire need of mathematics class (the obvious choice)
- DVD-burners can't burn over 4480MB (I'd still like to know why the capacities are overstated)
- File system eats the missing 300MBs (how can it?)
- something crucial I haven't noticed

To many this may seem like a whining of a no-lifer, but to me, there are few reasons to get upset with this:
1) I need the whole announced capacity of 4.7GB
2) I really hate to pay the prize of a 4812.8MB disc and get a 4483MB disc

Why is it so? Is this a standardized lie, that is OK to make customers pay 6,85% extra for capacity that is not there? When buying a CD-R, I know it can take the 650MB/700MB of data, no less. Or I (should) get a refund. It's a funny world if customer has to know the specs if he want's not to get lied to (too often it is, I guess...)

Any clarification would be welcome.

Thank you.

[parsifal]

Well, I have to answer to my own post.

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

The result is that today "everybody" does not "know" what a megabyte is. When discussing computer memory, most manufacturers use megabyte to mean 220 = 1 048 576 bytes, but the manufacturers of computer storage devices usually use the term to mean 1 000 000 bytes. Some designers of local area networks have used megabit per second to mean 1 048 576 bit/s, but all telecommunications engineers use it to mean 106 bit/s. And if two definitions of the megabyte are not enough, a third megabyte of 1 024 000 bytes is the megabyte used to format the familiar 90 mm (3 1/2 inch), "1.44 MB" diskette. The confusion is real, as is the potential for incompatibility in standards and in implemented systems.

Faced with this reality, the IEEE Standards Board decided that IEEE standards will use the conventional, internationally adopted, definitions of the SI prefixes. Mega will mean 1 000 000, except that the base-two definition may be used (if such usage is explicitly pointed out on a case-by-case basis) until such time that prefixes for binary multiples are adopted by an appropriate standards body.

It's never nice to be wrong. :/

And one can't even access the standards without paying first. Behind-closed-doors-standards.

[WebHead]

I,.. Uh,.. Um. wow.

I think you just won the first ever Windrivers Nerd of the Year award.

[TripleRLtd]

That's an idea wrbby.
Every disk, whatever format needs a Master File Table MFT as well as two copies of the FAT. At the beginning, we have a disk with tracks and sectors--but nothing written on them. Then, when you format with FAT or NTFS you start theprocess of writing the file system structures on the disk that let the disk be used for storing programs and data. All of this takes space from the actual capacity: this is all a "database" of the file system. All media, whether hard drives, floppies, or CD's or DVD's, whatever type of file system, NEED a way for the OS to recoginize the media, read it, and access it, and that "table" take room away from the actual full capacity.

[flackt]

It's the same reason your hard drive never comes close to what it is labled.

Math Lesson.

http://www.anandtech.com/guides/viewfaq.html?i=136


If your new to burning DVD's check this out it THE BEST DVD back up software ever and its FREE.

http://www.dvdshrink.org/what.html


These sights are helpful too.

http://www.videohelp.com/

http://www.digitalfaq.com/

[athlon]

You seem more like a noobie.

How in the world did u not know that manufactures uses 1,000 standard instead of the 1,024 standard. Every boob who's dealt with any type of storage device in the last 10 years knows this.

Edited by NooNoo: While you may be technically minded enough to know these things, people who use computers as just a tool do not need to. Come to think of it, were you born knowing bits, nibbles, bytes, words or did you learn it from somewhere?

[athlon]

4700000000 / 1024 = 4589843.75 KB
4589843.75 / 1024 = 4482.26 MB

By the way overhead is around 78 MB so you get 4.3GB of storage.

[confus-ed]

You seem more like a noobie.

How in the world did u not know that manufactures uses 1,000 standard instead of the 1,024 standard. Every boob who's dealt with any type of storage device in the last 10 years knows this.

Well that's very nice ain't it ?

(though yeah its just a 'moan' - but if affects a great deal of folks & not just 'noobies' either !)

All computing terms for size should be based on powers of 2 not rounded, but we live in a dinary world (so that's using decimal or base 10) computers if you hadn't noticed use binary all the time for everything - so its the manufacturers & apparently the IEEE who are 'wrong' & accept these approximations not the 'noobies' !

btw 'overhead' is dependant on file system used & number of files & directory structure & even burner unit itself so you can't say 'always 78 mb'

..Every disk, whatever format needs a Master File Table MFT as well as two copies of the FAT...

Errr except that CDs generally use CDFS which is totally different & has no need for two file allocation tables - its a 'write once' format & so there's no need to have two copies - it only needs one (not generally getting updated) - DVDs use a subset of UDF (Universal Disk Format) called micro UDF (M-UDF). Some details here - there's a whole load of other file systems DVD/CD can use too (despite what I just noticed the link says - it means for ones that'll work in a 'player' ) - but they are then dependant on device & machine specific features to work (hence why packet written CD's won't generally work in 'players' etc)

..If your new to burning DVD's check this out it THE BEST DVD back up software ever and its FREE.

http://www.dvdshrink.org/what.html

Gets a big from over here, my favourite DVD 'shrinking' program - which you'll need anyway (or similar) for various DVD formats which hold up to 9.4 gig (or whatever the hell that actually turns out to be ! )

& then of course there's 'unused capacity' to think about - I have a DVD unit that does CD 'HD' so I can burn 1.4 gig on a 700mb cd - neat huh ? That uses firmware to make better use of the surface tracking effectively writting another concentric track besides the 'normal' one in the space between the loops of the spiral, but of course I can only use these 'HD cds' in my or another HD equiped unit - so at the end of the day your blank DVDs potentially have a whole load more capacity if you are 'sneaky enough' to figure out how to use it !! - so what are you moaning about ?

[corturbra]

Well that's very nice ain't it ?

(though yeah its just a 'moan' - but if affects a great deal of folks & not just 'noobies' either !)

All computing terms for size should be based on powers of 2 not rounded, but we live in a dinary world (so that's using decimal or base 10) computers if you hadn't noticed use binary all the time for everything - so its the manufacturers & apparently the IEEE who are 'wrong' & accept these approximations not the 'noobies' !

btw 'overhead' is dependant on file system used & number of files & directory structure & even burner unit itself so you can't say 'always 78 mb'



Errr except that CDs generally use CDFS which is totally different & has no need for two file allocation tables - its a 'write once' format & so there's no need to have two copies - it only needs one (not generally getting updated) - DVDs use a subset of UDF (Universal Disk Format) called micro UDF (M-UDF). Some details here - there's a whole load of other file systems DVD/CD can use too (despite what I just noticed the link says - it means for ones that'll work in a 'player' ) - but they are then dependant on device & machine specific features to work (hence why packet written CD's won't generally work in 'players' etc)



Gets a big from over here, my favourite DVD 'shrinking' program - which you'll need anyway (or similar) for various DVD formats which hold up to 9.4 gig (or whatever the hell that actually turns out to be ! )

& then of course there's 'unused capacity' to think about - I have a DVD unit that does CD 'HD' so I can burn 1.4 gig on a 700mb cd - neat huh ? That uses firmware to make better use of the surface tracking effectively writting another concentric track besides the 'normal' one in the space between the loops of the spiral, but of course I can only use these 'HD cds' in my or another HD equiped unit - so at the end of the day your blank DVDs potentially have a whole load more capacity if you are 'sneaky enough' to figure out how to use it !! - so what are you moaning about ?

Wow, you sound like either you know your stuff or you need to get out more....

[confus-ed]

Wow, you sound like either you know your stuff or you need to get out more....

Quiet days at the office (in my glorified shed actually !) waiting for dumb couriers to arrive with parts give me opportunity to 'vent' my 'techo knowledge' on the world (I do lots of 'techo writing' {summarising 'guff' for humans !) & testing nowadays besides routine pc stuff & the odd network job & my mainstay cabling) & I like to share my knowledge with others {particularly liking ones where I can 'waffle' a bit & especially when folks can pick up on any misconceptions I might have & correct me }, as its how I've learnt many many things, so one good turn & all ..

As for getting out more I think my bank manager & the local pub might just have the other opinion !

[TechZ]

A 760MB file in VCD format can fit on a 700 MB CD, if its less than 80minutes, so that rule should apply to DVD's also right.

[corturbra]

Quiet days at the office (in my glorified shed actually !) waiting for dumb couriers to arrive with parts give me opportunity to 'vent' my 'techo knowledge' on the world (I do lots of 'techo writing' {summarising 'guff' for humans !) & testing nowadays besides routine pc stuff & the odd network job & my mainstay cabling) & I like to share my knowledge with others {particularly liking ones where I can 'waffle' a bit & especially when folks can pick up on any misconceptions I might have & correct me }, as its how I've learnt many many things, so one good turn & all ..

As for getting out more I think my bank manager & the local pub might just have the other opinion !

Well, you do know your stuff, it's helped me on more than one occasion, but I still think you should get out more.

Have some drink on me