DVDs are said to hold 4.7gb but in reality only hold about 4.4gb. I'm guessing it's because the manufacturers measure bytes in 1000s instead of 1024s. But if that's the case, how come CDs can hold their advertised amount, and sometimes an extra couple mb?
2007-03-08 04:08:13 · 6 answers · asked by Graham T 2 in Computers & Internet ➔ Hardware ➔ Add-ons
The problem is that computers and DVD drives and its media count the numbers differently. Computers count according to a binary system (base 2). The creators of DVD standards decided to count bytes in a decimal system (like a human counts). A DVD labelled for 4.7GB capacity actually only holds 4.39GB in computer terms.
Total storage capacity may be even less on DVD+RW and DVD-RW discs, because these discs require formatting before or during burning, and the format takes up space as well.
This decision was made by the DVD industry — the standards.
The CD industry standard is different. They use a term for storage called "RAM".
The "MB" for RAM means 1024x1024, but for hard drives it means 1000x1000. A data CD that can hold 650 "RAM" MB of data holds about 682 "disk" MB of data.
Examples of Data or Audio storage on CDs:
63 minutes == 283,500 sectors == 553.7MB CD-ROM == 635.9MB CD-DA
74 minutes == 333,000 sectors == 650.3MB CD-ROM == 746.9MB CD-DA
80 minutes == 360,000 sectors == 703.1MB CD-ROM == 807.4MB CD-DA
This is why they "appear" to hold as much data as they advertise....the unit of measurement is different.
sources :
http://www.imation.com/support/products/dvd_media.html#04
http://www.cdrfaq.org/faq07.html#S7-6
regards,
Philip T
2007-03-08 06:11:41 · answer #1 · answered by Philip T 7 · 0⤊ 0⤋
The difference is related to the space used by the files that are necessary for formatting the CD or DVD. DVDs require larger formatting files.
2007-03-08 04:13:03 · answer #2 · answered by Anonymous · 0⤊ 0⤋
hi there are softwares available on the net which can compress the data. e.g a 6gb data can be compressed to less then 4gb but the quality of image may be poor. keep trying to get the right compression form various softwares available ( www.downloads.com)
2007-03-12 00:47:17 · answer #3 · answered by Jason W 2 · 0⤊ 0⤋
compression more than likely
straight up 700 mb of data vs 700 mb of compressed data is 2 different things.
2007-03-16 03:35:40 · answer #4 · answered by me_myself125 3 · 0⤊ 0⤋
i have noticed that with some DVDs there is a pre-installed/pre-burned program that allows burners to identify the type of media that is in the drive.
this may not be what you are looking for.....
2007-03-15 09:21:51 · answer #5 · answered by seaweed917 1 · 0⤊ 0⤋
my all dvds stores 4.7 gb of data
2007-03-08 07:04:02 · answer #6 · answered by GoLd E 5 · 0⤊ 0⤋