Comprehensive FAQ on DVDs: http://www.dvddemystified.com/dvdfaq.html This FAQ is updated at least once a month.
See also http://www.afterdawn.com
Site that offers DVD rippers, DivX and
DVDR news, P2P tools, guides, software downloads and much more.
Pronunciation: DVD-R is pronounced "dash R", not "minus
R".
Drive speed: 16x is the theoretical maximum.
DVD-ROM: DVD-Read Only Memory, disks are 12cm in diameter.
Physically the same size as the CD-ROM, or Compact Disc, but can store information
at much higher densities giving a greater capacity.
The increase in capacity over a standard CD-ROM, for a single layer,
is about 7 times.
The increase in capacity is due to: 1. smaller pit length (~2.08x), 2.
tighter tracks (~2.16x),
3. slightly larger data area (~1.02x), 4. more efficient channel bit modulation
(~1.06x),
5. more efficient error correction (~1.32x), 6. less sector
overhead (~1.06x).
The capacity of a dual-layer disc is slightly less than double that
of a single-layer disc. The laser has to read "through" the outer
layer to the inner layer (a distance of 20 to 70 microns). To reduce inter-layer
crosstalk, the minimum pit length of both layers is increased from 0.4 um to
0.44 um. To compensate, the reference scanning velocity is slightly faster,
3.84 m/s, as opposed to 3.49 m/s for single layer discs. Longer pits, spaced
farther apart, are easier to read correctly and are less susceptible to jitter.
The increased length means fewer pits per revolution, which results in reduced
capacity per layer.
Note: Older versions of Windows that use FAT16, instead of UDF, FAT32, to read
a DVD may run into problems with the 4 gigabyte volume size limit.
FAT16 also has a 2 gigabyte file size limit, while FAT32 has a 4 gigabyte file
size limit.
NTFS has a 2 terabyte limit, so we're ok there for a while.
It takes about two gigabytes to store one hour of average video.
Physical Formats
12cm diameter DVD-ROMs can currently be made in four physical formats named
DVD-5, DVD-9, DVD-10 and DVD-18.
(DVD-1 to DVD-4 are 8cm diameter disks.)
DVD-5 has 4.7GB storage capacity (versus the 650MB standard for a CD-ROM) and
stores the data on one side of the disc in a single layer. This data can be
in the form of software, video (DVD-Video) or audio (DVD-Audio).
DVD-9 format uses a single side of the disc and stores data in dual layers.
DVD-10 format uses both sides of the disc to store data in a single layer.
DVD-18 format uses both sides of the disc to store data in dual layers.
DVD-ROM discs can be accessed in set top DVD players and computers equipped
with DVD-ROM drives.
These discs cannot be written to by the user.
A DVD-18 requires a completely different way of creating two layers. A single-sided,
dual-layer disc (DVD-9) is produced by putting one data layer on each substrate
and gluing the halves together with transparent adhesive so that the pickup
laser can read both layers from one side. But in order to get four layers, each
substrate needs to hold two. This requires stamping a second data layer on top
of the first, a much more complicated prospect. Only a few replicators can make
DVD-18s, and the low yield (number of usable discs in a batch) makes it more
difficult and expensive than making DVD-9s.
Small disks:
DVD-1 (8 cm, SS/SL) 1.36 gig (1.46 BB), about half an hour
DVD-2 (8 cm, SS/DL) 2.47 gig (2.66 BB), about 1.3 hours
DVD-3 (8 cm, DS/SL) 2.72 gig (2.92 BB), about 1.4 hours
DVD-4 (8 cm, DS/DL) 4.95 gig (5.32 BB), about 2.5 hours
DVD-R, DVD-RW and DVD-RAM (Pronunciation: DVD-R is pronounced "dash R",
not "minus R".)
These formats are supported by Panasonic, Toshiba, Apple Computer, Hitachi,
NEC, Pioneer, Samsung and Sharp.
These formats are also supported by the DVD Forum.
DVD-R (Digital Versatile Disc - Recordable) These discs can only be written
to once by the user.
A disc that is equivalent to the DVD-ROM but it can also be recorded to. The
Pioneer DVR-A05U drive can record
4.7GB single-sided and
9.4GB double-sided DVD-R discs. DVD-R was first available in 1997
DVD-R discs can be accessed in set top DVD players and computers equipped with
DVD-ROM drives.
DVDs for Authoring or for General Use
Two types of DVD-R drives and media: DVD-RA and DVD-RG
DVD-RA or DVD-R(A), for Authoring, is appropriate for someone who wants
to create a disc that can be used as a master at a duplication house. This is
called the Cutting Master Format (aka CMF).
A portion of the lead-in area can store the DDP (Disk Description Protocol)
header information normally used on DLT master tapes (DLT = Digital Linear Tape).
It supports setting region codes (for the different regions of the world) and
using copy protection. It is supported by the DVR-S201. More info
on Region Codes: click
here
DVD-R(A) is intended for professional development and uses a 635-nm laser (more
expensive than the 650nm laser).
DVD-R(A) discs are not writable in DVD-R(G) recorders, and vice-versa, but both
kinds of discs are readable in most DVD players and drives.
DVD-RG or DVD-R(G), for General use, is appropriate for someone who only wants to create a few copies of a disc and doesn't need to send the disc to a duplication house or set region codes. Supported by the DVR-A05U.
The DVD-RG (general version), intended for home use, writes with a cheaper
650-nm laser, the same as DVD-RAM.
DVD-RG contains content protection that makes it physically impossible to make
bit-for-bit copies of CSS encrypted entertainment titles. CSS = Content Scramble
System. DeCSS is software to decrypt the files.
The main differences, in addition to recording wavelength, are as follows:
DVD-R(G) uses decrementing pre-pit addresses,
there is a control area which is pre-stamped (version 1.0) or pre-recorded (version
1.1),
can use CPRM (see below, see 1.11), and
allows double-sided discs.
See http://www.pioneerelectronics.com/Pioneer/Files/DVDR_whitepaper.pdf
In general, region codes don't apply to recordable DVDs. A DVD that
you make on a PC with a DVD burner or in a home DVD video recorder will play
in all regions (but don't forget NTSC vs. PAL differences, see 1.19). Region
codes do not apply to DVD-Audio. More info: click
here or http://faq.inmatrix.com/
How can I find out if my DVD drive is region locked? Click
here The Firmware
Page
Copy Protection Issues: for details, click
here There are many forms of content protection that apply to DVD.
CPSA (content protection system architecture) is the name given to the
overall framework for security and access control across the entire DVD family.
Analog CPS Macrovision - CGMS - CPPM - CPRM - DCPS - HDCP, DVI, and HDMI
CSS Content Scramble System, is a data encryption and authentication scheme
intended to prevent copying video files directly from DVD-Video discs. DVD players
have CSS circuitry that decrypts the data before it's decoded and displayed,
and computer DVD decoder hardware and software must include a CSS decryption
module. In October 1999, the CSS algorithm was cracked and posted on the Internet,
triggering endless controversies and legal battles.
CPRM: Content Protection for Recordable Media. CPRM is a mechanism that
ties a recording to the media on which it is recorded. It is supported by some
DVD recorders, but not by many DVD players. Each blank recordable DVD has a
unique 64-bit media ID etched in the BCA (see 3.11). When protected content
is recorded onto the disc, it can be encrypted with a 56-bit C2 (Cryptomeria)
cipher derived from the media ID. During playback, the ID is read from the BCA
and used to generate a key to decrypt the contents of the disc. If the contents
of the disc are copied to other media, the ID will be absent or wrong and the
data will not be decryptable.
More info: http://www.mpaa.org/Press/DVD_FAQ.htm
Prices for blank DVD-R(A) discs are $10 to $25 (down from the original
$50), although cheaper discs seem to have more compatibility problems.
Prices for blank DVD-R(G) discs are $2 to $6.
Recordable DVD See http://www.dvddemystified.com/dvdfaq.html#4.3
"Super multi" drives can record all 5 disc types (DVD-R, DVD-RW, DVD+R, DVD+RW, and DVD-RAM).
[4.3.6] Which recordable DVD format should I buy?
As explained in the previous sections, there are two main formats: "dash"
(DVD-R/RW) and "plus" (DVD+R/RW). There's not much difference between
them. They both record data and video, and they both read back data and play
back video. Both formats are available as recordable drives for computers and
as home video recorders. In spite of claims that one format is more compatible
with players and drives, both formats are similarly compatible (see 4.3.1).
There are speed differences, but it's a game of leapfrog. One format will come
out with faster write speeds, then the other one will match it or surpass it.
In 2003, drives reached 8x speeds. 16x is the theoretical maximum, so both formats
will soon hit the limit.
The biggest thing to worry about is that DVD-RW drives only record on -R
and -RW discs, and DVD+RW drives only record on +R and +RW discs, so you
have to make sure you get the right kind of blank discs.
You may worry that one of the formats might "win" and the other format
could disappear, leaving you with abandoned hardware. This is not very likely,
since both formats are doing well.
Luckily there is a simple solution to both concerns: buy a dual-format, or "combo"
drive. Many companies make DVD-/+RW drives that write to both kinds of discs.
Dual-format drives cost a bit more, but it's cheap insurance.
The DVD+RW format has a few advantages when used in a computer, but if data
backup or access speed is important, also consider the DVD-RAM format.
DVD-RAM is fast and reliable, and the discs have an optional cartridge
to help protect data.
Most DVD-RAM drives also write DVD-R/RW discs, and some super combo drives write
all three formats.
Panasonic DVD/CD Player DVD-S27 plays DVD-R, but not DVD+R, +RW or DVD-RW
DVD-RW (Digital Versatile Disc - Re-Writable)
A version of the write-once DVD-R format that can be written to up to 1,000
times. The Pioneer DVR-A05U drives can record on single-sided 4.7GB DVD-RW discs.
DVD-RW discs can be accessed in set top DVD players and computers equipped
with DVD-ROM drives.
DVD-RW discs may not play back on some older or entry-level DVD systems
They became available in the U.S. in 2001.
DVD-RW drives write DVD-R, DVD-RW, CD-R, and CD-RW discs.
DVD+R and DVD+RW formats are supported by Philips, Sony, Hewlett-Packard,
Dell, Ricoh, Yamaha and others.
DVD+R (Digital Versatile Disc + Recordable). DVD+R was released in mid 2002.
A specification put forward by the DVD+RW Alliance.
DVD+R discs can be recorded in 4.7GB capacities. These discs can only be written
to once by the user.
DVD+R discs can be accessed in set top DVD players and computers equipped
with DVD-ROM drives.
DVD+RW (Digital Versatile Disc + Re-Writable). DVD+RW became available in late
2001.
A different version of a re-writable DVD-R format that is designed to be more
suitable for both real-time video recording and random data recording.
DVD+RW discs can be recorded in 4.7GB capacities.
DVD+RW discs can be accessed in set top DVD players and computers equipped with
DVD-ROM drives.
DVD+RW discs may not play back on some older or entry-level DVD systems
DVD-R & RW and DVD+R & RW are essentially in competition with each
other.
There are many claims that one or the other format is better, but they are actually
very similar.
In 2003 many companies began making drives that could record in both formats.
DVD-RW drives only record on -R and -RW discs, and
DVD+RW drives only record on +R and +RW discs, so you have to make sure you
get the right kind of blank disks.
The DVD+RW format has a few advantages when used in a computer, but if
data backup or access speed is important, also consider the DVD-RAM format (see
below).
DVD-RAM (DVD - Random Access Memory)
DVD-RAM is fast and reliable, and the discs have an optional cartridge to help
protect data.
Most DVD-RAM drives also write DVD-R/RW discs, and some super combo drives write
all three formats.
Differs from the DVD-R in that it is re-writable many times. Discs are available
in capacities of
2.6GB or 4.7GB for single sided discs and
5.2GB or 9.4GB for double sided discs. The Panasonic LF-D521U drive can record
to and read from these media.
DVD-RAM discs can only be accessed in a DVD-RAM drive.
They cannot be used in set top DVD players or computers equipped with DVD-ROM
drives.
DVD-RAM discs are typically housed in cartridges.
DVD-RAM is more of a removable storage device for computers than a video recording
format, although it has become widely used in DVD video recorders because of
the flexibility it provides in editing a recording.
DVD Multi
A player with the DVD Forum's "DVD Multi" is guaranteed to read DVD-R,
DVD-RW, and DVD-RAM discs,
and a DVD Multi recorder can record using all three formats (i.e. also DVD+R
& DVD+RW).
Some new "super combo" drives can record in both dash and plus
format,
and a few "super multi" drives can record all 5 disc types
(DVD-R, DVD-RW, DVD+R, DVD+RW, and DVD-RAM).
In addition, not all players and drives can read recorded discs. The basic
problem is that recordable discs have different reflectivity than pressed discs
(the pre-recorded kind you buy in a store -- see 5), and not all players have
been correctly designed to read them.
More information: http://www.dvddemystified.com/dvdfaq.html#4.3
FAQ on DVDs http://www.dvddemystified.com/dvdfaq.html This FAQ is updated at least once a month.
[3.12] How long do DVDs last?
DVDs are read by a laser, so they never wear out from being played since nothing
touches the disc. Pressed discs (the kind that movies come on) will probably
last longer than you will, anywhere from 50 to 300 years.
Expected longevity of dye-based DVD-R and DVD+R discs is anywhere from 20 to 250 years, about as long as CD-R discs. Some dye formulations (such as phthalocyanine and azo) are more stable and last longer, 100 years or more, compared to 20 or 30 years for less stable dyes.
The phase-change erasable formats (DVD-RAM, DVD-RW, and DVD+RW) have an expected lifetime of 25 to 100 years.
In all cases, longevity can be reduced by poor quality. Poor quality pressed DVDs may deteriorate within a few years, and cheap recordable DVDs may produce errors when recording or may become unreadable after a while. (See 1.24.)
For more info see Lifetime of KODAK CD-R Ultima Media and www.ee.washington.edu/conselec/CE/kuhn/otherformats/95x9.htm
For comparison, magnetic media (tapes and disks) last 10 to 30 years; high-quality, acid-neutral paper can last 100 years or longer; and archival-quality microfilm is projected to last 300 years or more. Note that computer storage media often becomes technically obsolete within 20 to 30 years, long before it physically deteriorates. In other words, before the media becomes unviable it may become difficult or impossible to find equipment that can read it.
[4.3.9] Which color of recordable DVD is best?
Different colors of recordable CDs and DVDs come from the combination of the
reflective metal layer (gold or silver) and the dye used in the recording layer
(cyanine [blue], phthalocyanine [clear], azo [dark blue], formazan [green],
etc.). Judging DVD quality by color is like judging bell pepper quality by color
(is yellow better than red or green?). You may find that some color discs seem
to work better in some players, but you'll also find that there is little correlation
between color and readability across multiple brands of disc. Other factors
such as manufacturing quality and chemical formulation have much more of an
effect on how well a disc records and plays back.
Color does indicate longevity, since some dyes (such as phthalocyanine [clear] and azo [dark blue]) are more stable and last longer. See 3.12.
[4.3.11] What does 2x, 4x, 16x, and so on mean on recordable discs,
and which one should I use?
Recordable discs come in different speed ratings (2x = twice standard write
speed, 8x = eight times standard speed, and so forth). The speed ratings of
blank discs match the speed ratings of drives (see 4.2). When faster drives
become available, new discs are designed to work with the new drives as well
as older drives. This means you should use discs that are rated at or above
the speed of your drive. For example, if you have a 4x drive you should use
4x or faster discs, not 1x or 2x.