"4,7 GB = 120 min." - why?

[clokkevi]

On the cover of single-layer DVD-R's / DVD+R's it says "4,7 GB / 120 min"
- why is that?

I know on CD-R's it says "700 MB / 80 min" because that CD-R
has 360,000 sectors, and..:

Data capacity:
360,000 sectors * 2048 bytes/sector data track = 737,280,000 bytes data
(737,280,000 bytes) / (1024 bytes/KB) = 720,000 KB
(720,000 KB) / (1,024 KB/MB) = ca. 703 MB
So it can store ca. 703 MB data.

Audio capacity:
360,000 sectors * 2,352 bytes/sector audio track = 846,720,000 bytes audio
44,100 samples/second * 2 bytes/sample * 2 (stereo) = 176,400 bytes/second
(846,720,000 bytes) / (176,400 bytes/second) = 4,800 seconds
(4,800 seconds) / (60 seconds/minute) = 80 minutes
So it can store exactly 80 minutes of audio.

But when it comes to the amount of sectors on DVD-R's / DVD+R's...
According to OSTA there are some different numbers..
http://www.osta.org/technology/dvdqa/dvdqa6.htm

DVD+R:
DVD+R Specification Version 1.2 - 2,295,104 sectors (4,700,372,992 bytes)

DVD-R:
DVD-R (General) Specification Version 2.0 - (2,294,922 sectors) 4,700,000,000 bytes
Although this is the minimums,
most manufacturers are using 2,298,496 sectors (4,707,319,808 bytes)


The reason for the "4,7 GB" stamp is because they use decimal 10-base notation
- 1 GB = 1,000 KB = 1,000,000 bytes
instead of the usual binary 2-base notation (like Windows use)
- 1 GB = 1,024 KB = 1,048,576 bytes



So.. how does those 2,295,104 / 2,294,922 / 2,298,496 sectors
gets translated to "120 minutes"...?

120 minutes * 60 seconds/minute = 7,200 seconds

(2,295,104 sectors) / (7,200 seconds) = 318,764444444..... sectors/second
(2,294,922 sectors) / (7,200 seconds) = 318,739166666..... sectors/second
(2,298,496 sectors) / (7,200 seconds) = 319,235555555..... sectors/second

Clearly, any rigid "sectors/second" specification
- like the "75 sectors/second" from CD's
- is not used for DVD-R's or DVD+R's.

Some manufaturers, like BenQ, thinks that 120 minutes of digital audio
will take as much as 4,7 GB:
http://www.benq.com.au/HomeProductList.asp?bc=30
"Offering the storage capacity of 4.7GB of data or 120 minutes of digital audio, BenQ's DVDR media enables you..."
(I don't think I'll ever by any media from BenQ..!)


Let's use the 2,298,496 sectors (4,707,319,808 bytes) DVD size.

4,707,319,808 bytes * 8 bits/byte = 37,658,558,464 bits
37,658,558,464 bits / 7,200 seconds = ca. 5,230,355 bits/second
(ca. 5,230,355 bits/second) / (1,024 bits/Kbits) = ca. 5,108 Kbits/second.

As far as I know, the DVD bitrate is variable.
How can they set "120 min" on the cover?
Could it be some old typing error, that it should say "120 mm" (the diameter of the DVD) instead..?

[Inventive Software]

The reason for the "4,7 GB" stamp is because they use decimal 10-base notation
- 1 GB = 1,000 KB = 1,000,000 bytes
instead of the usual binary 2-base notation (like Windows use)
- 1 GB = 1,024 KB = 1,048,576 bytes

Unfortunately manufacturers are being this way more and more, and it's very misleading. Hard disk manufacturers do it as well.

4.7 GB is a nicer number than the exact number of bytes or GB that are on the disc. CDs you'll find have maybe 79 mins 57 seconds, which is as near as dammit 80 mins. 703 MB is also as near as dammit 700 MB. The reason is it's very difficult to engineer a CD to exactly the "White Paper" specs. Doing so would also drive the cost up a lot. Making something to within "reasonable limits" is more cost-efficient and also allows for discrepencies within the manufacture process.

120 mins for the DVD recording is the average time you'll get. That particular notation is the standard time you'll get with a DVD recorder (standalone). With different recording modes you can extend the recording time (LP is 240 mins, EP is 360 mins).

In short, it's just a standard that's been adopted, and stuck with out of convenience. Live with it.

[fccHandler]

Originally posted by Inventive Software
Unfortunately manufacturers are being this way more and more, and it's very misleading. Hard disk manufacturers do it as well.

Surprisingly, I recently found out that it isn't their fault. They are actually doing it right, and everyone else (especially Microsoft) has got it wrong.

According to the IEC 60027-2 standard, a gigabyte really is 1,000,000,000 bytes! A gibibyte is 1,073,741,824 bytes.

[Soulhunter]

Seems they gonna use this 120 min. scheme also for future media...




Bye

[Mug Funky]

MPEG-2 is VBR, so running time is utterly meaningless.

however, if you assume a constant (or average) bitrate of about 5000 kbps, then you'll get about that long on a DVD-5.

it is all marketing after all, though. i would never put that much video on a DVD-5 - you just can't guarantee it'll look good at that bitrate.

of course, you could fit heaps of video on a DVD-5 if it were in h.264...

[mpucoder]

The time values are for DVR, this is how much time you can record at SP. It's analogous to a T120 VHS tape. (Maybe that's why Beta failed as a consumer medium, people could not equate L750 to 3 hours)

[communist]

Originally posted by fccHandler
Surprisingly, I recently found out that it isn't their fault. They are actually doing it right, and everyone else (especially Microsoft) has got it wrong.

According to the IEC 60027-2 standard, a gigabyte really is 1,000,000,000 bytes! A gibibyte is 1,073,741,824 bytes.

Exactly!
Its always fun to hear people moaning about being cheated about a few 'GB' when they format their brand new hdds

[dragongodz]

well i was not going to bother saying anything but what the hell, may aswell play a little devils advocacy. as such these comments are just meant to show you the other side of the story and should not be taken personally.

Surprisingly, I recently found out that it isn't their fault. They are actually doing it right, and everyone else (especially Microsoft) has got it wrong.

According to the IEC 60027-2 standard, a gigabyte really is 1,000,000,000 bytes! A gibibyte is 1,073,741,824 bytes.

that was only introduced in December 1998 to try and help ease the confusion, it failed. computers have been around a LOT LONGER than that and used the terms kilobyte etc first. now because digital A/V programs etc decided to use base 10 and still use the same terms anything else to do with computers should change ? why ? they were first and have a huge amount of both hardware and software out there that simply can not be changed. a better question is why didnt A/V use different terms to start with. so who is really to blame ?

The time values are for DVR, this is how much time you can record at SP.

exactly. which is why dvd media give both size and time, so it is saying it is A/V related and so can use the base 10 to tell you that size. you may say that dvd media is not only used for A/V and you would be right of course. that however doesnt change what the size and time are meant to signify.

Its always fun to hear people moaning about being cheated about a few 'GB' when they format their brand new hdds

also consider that they are giving you what is meant to be the raw size and not formatted. why ? well which formatted size should they list exactly ? FAT, NTFS, EXT, HTFS, OTHER ? they do not produce the exact same size. maybe people would like them to list the size for every possible formatting combination but i doubt they think that should be needed. as for saying HD manufacturers are using base 10 so not at fault, wrong. they have used raw size for a very long time(personal experience with this from the early 80's), well before that IEC doc came out.

as i said at the start, this is just to encourage people to think and see both sides so please dont try and flame me, i wouldnt take that kindly.

[fccHandler]

Originally posted by dragongodz
that was only introduced in December 1998 to try and help ease the confusion, it failed. computers have been around a LOT LONGER than that and used the terms kilobyte etc first.

True enough. And I'm just as guilty of forever assuming 1KB = 1024 bytes, but I'll play the opposing side just for the sake of argument.

To ease confusion, there has to be some rule that everyone will agree to. The IEC attempted to set a standard in 1998, so you would think Microsoft had enough time to incorporate the new math into Windows XP. Yet they didn't.

The IEC standard is clear and concise (though I confess "gibibyte" doesn't roll off the tongue as fluidly as "gigabyte," LOL). So if/when Microsoft finally adopts it (and perhaps only then), I think it's pretty much guaranteed to become global law. Until that happens, or until a more agreeable standard comes along, Windows users remain mired in confusion.

I have wondered if Microsoft's failure to implement the IEC standard is due to backwards compatibility issues. But I find it difficult to rationalize, considering that many of my old DOS games and programs don't work correctly under XP. As a user, it seems that I gave up "backwards compatibility" when I upgraded from Win98 in the first place...

[movmasty]

Originally posted by clokkevi
"4,7 GB = 120 min." - why?

Well, really at the begin were "135 minutes",

but now also a movie of 90 min. is double layered, usually they fit about 70 min. in one layer...

Anyone up to compare DVD and vhs tapes?

How many vhs240 is a DVD?

[Mug Funky]

interesting... i wonder how much footage in half-d1 could be squeezed on a DVD before the quality falls below that of VHS...

i'm sure you could fit around 8 hours quite comfortably on a DVD-5 if you're only aiming for VHS quality.

[dragongodz]

To ease confusion, there has to be some rule that everyone will agree to. The IEC attempted to set a standard in 1998, so you would think Microsoft had enough time to incorporate the new math into Windows XP. Yet they didn't.

that first statement highlights the problem, how many in the computer related businesses agreed to it ? this includes not only software but hardware.
for example how many ram manufacturers are sticking kibi on their stickers ? none i have seen.
is Mac using kibi (as in on screen, reporting hd and/or ram size etc)? i dont know.
are Linux distros using kibi (again screen)? i know it was added to the kernel several years ago and there was complaints then about it causing confusion. couldnt find anything more about it though.
how about third party software manufacturers(for any platform) ? have they started using kibi in their displays ? cant say i have seen this happening either.

so this is not just a MS thing but a much wider spread non-acceptance.

[movmasty]

Originally posted by Mug Funky
interesting... i wonder how much footage in half-d1 could be squeezed on a DVD before the quality falls below that of VHS...

i'm sure you could fit around 8 hours quite comfortably on a DVD-5 if you're only aiming for VHS quality.

so dvd5=2x vhs240? one $ for 6 $...

Half d1 you mean 352x576/480?
8 hours on a dvd is 159kb/s, this is the mpg1 bitrate, 352x288.

but using lp a svhs can play 8 hours on a tape with better quality than mpeg1

but still using xvid we can put 10 hours of movies on a dvd with better quality respect to the svhs....

[Joe Fenton]

I'm with dragongodz on this one. There isn't a computer user alive (much less a programmer or hardware engineer) that would be CAUGHT DEAD using those crappy IEC terms. That was the stupidest thing ever conceived, and you can bet the IEC didn't consult a single computer expert while making this 'standard'. It's just jealous mathmeticians trying to embarass software programmers making ten times their salary.

I won't ever use those units in anything I write, and neither will anyone I know. They're just plain stupid. Who did they consult when making up those units? The director's three year-old? I have an idea - the base-10 camp can use the following units:

10e3 - kissy
10e6 - missy
10e9 - gissy
10e12 - tissy

Have fun getting magazines to print THOSE units!

[fccHandler]

Well, how about:

Killer-byte
Miller-byte
Godziller-byte
Thriller-byte

In all honesty, I agree the IEC terms sound like baby talk. Big hunky macho programmers don't want to talk like that. I didn't exactly say it in my previous post, but I kinda alluded to a similar misgiving on my part.

But is that the only reason people won't adopt them? Because if it is, don't you think it's kind of a silly reason? I'm sure we'll get over it once everybody is using the terms (if that ever happens).

[Joe Fenton]

You have to give people a compelling reason to change or they won't. So, name one reason to change - the IEC is TELLING you to. Is it compelling? Not in the slightest.

Now name a reason to NOT change - tradition, confusion, the IEC picked stupid sounding terms, and finally, all current computer science materials (books, etc.) would have to be rewritten, republished, and repurchased. Is it compelling? You bet your posterior.

Hell, they couldn't get the US to go metric, and metric terms sound pretty cool. What in God's green Earth makes them think they could push that 'standard' when it makes you sound like an idiot?

[Shinigami-Sama]

Originally posted by Joe Fenton
You have to give people a compelling reason to change or they won't. So, name one reason to change - the IEC is TELLING you to. Is it compelling? Not in the slightest.

Now name a reason to NOT change - tradition, confusion, the IEC picked stupid sounding terms, and finally, all current computer science materials (books, etc.) would have to be rewritten, republished, and repurchased. Is it compelling? You bet your posterior.

Hell, they couldn't get the US to go metric, and metric terms sound pretty cool. What in God's green Earth makes them think they could push that 'standard' when it makes you sound like an idiot?

it's alway annoying have to tell metric <among other things > ignorant americans what a klick, meter, kilo, mill ect. is
but thats another topic
I agree though, atleast make the stuff sound smart, not lieka 3y/o's baly-rish

[fccHandler]

@Joe Fenton:

The IEC isn't "pushing" it on anyone. They are publishing an international standard (that's their job) which the industry will either accept or reject. IMHO "the terms sound stupid" is not a compelling reason to reject it, but some of your other points are certainly valid.

If all computer science materials will have to be rewritten, well, it's only because they were wrong to begin with. For example, the prefix "Kilo" (borrowed from the Metric system) is universally understood to mean 1000 units, and it's been that way for 200 years. What has screwed us up now is the fact that the computer industry adopted the same prefix, but redefined it as 1024 units!

The IEC's standard will eliminate this confusion once and for all, and to me that is an overwhelmingly compelling reason to adopt it.

But, like your example of the U.S. going metric, it just ain't gonna stick unless everyone agrees, especially the big players. I think Microsoft could set a tremendous example by adopting the standard in their next OS.

Will we sound like infants when we talk? Sure! But at least we'll agree on what we're talking about.

Remember the term "googol" (from which "Google" gets its name) was invented by a 10-year old child. Do people of today feel stupid saying the word "Google"? Absolutely not!

[Shinigami-Sama]

Originally posted by fccHandler
@Joe Fenton:

The IEC isn't "pushing" it on anyone. They are publishing an international standard (that's their job) which the industry will either accept or reject. IMHO "the terms sound stupid" is not a compelling reason to reject it, but some of your other points are certainly valid.

If all computer science materials will have to be rewritten, well, it's only because they were wrong to begin with. For example, the prefix "Kilo" (borrowed from the Metric system) is universally understood to mean 1000 units, and it's been that way for 200 years. What has screwed us up now is the fact that the computer industry adopted the same prefix, but redefined it as 1024 units!

The IEC's standard will eliminate this confusion once and for all, and to me that is an overwhelmingly compelling reason to adopt it.

But, like your example of the U.S. going metric, it just ain't gonna stick unless everyone agrees, especially the big players. I think Microsoft could set a tremendous example by adopting the standard in their next OS.

Will we sound like infants when we talk? Sure! But at least we'll agree on what we're talking about.

Remember the term "googol" (from which "Google" gets its name) was invented by a 10-year old child. Do people of today feel stupid saying the word "Google"? Absolutely not!

I"ll agree withteh kilo thing but google not sounding stupid..

anyways, yeah getting this stupid 10/2-base crap sorted out would be nice, much less math in hte long run converting this crap to that crap

[fccHandler]

Originally posted by Shinigami-Sama
getting this stupid 10/2-base crap sorted out would be nice

My point exactly.