The current state of recordable DVD media formats.CD-R and -RW continue to be the most widely used removable storage technology because of the extremely low cost of drives, players, and media. However, with prices for DVD DVD - Digital Versatile Disc (formerly Digital Video Disc) DVD - D-Von Dudley (wrestler) DVD - Death Valley Days (TV show) DVD - Death Valley Driver (pro wrestling) DvD - Depp Vom Dienst (German: Idiot of Service) DVD - Deutsche Vereinigung für Datenschutz DVD - Developmental Verbal Dyspraxia DVD - Dick Van Dyke (actor) DVD - Digital Video Disc (now Digital Versatile Disc) DVD - Digital Video Drive DVD - Direct Vendor Delivery hardware and media dropping, the DVD recordable formats are rapidly gaining acceptance for use in document, video, audio, and personal/professional storage. The prime selling points of DVD are its inherent reliability and massive data storage capabilities--ultimately up to 9.4GB of removable storage with a double-sided disc. According to Wolfgang Schlichting, IDC's Research Manager, Removable Storage, 2002 will be the year when many consumers will discover the benefits of DVD recording. IDC projects that worldwide DVD media sales will climb from 50 million discs in 2002 to nearly 150 million in 2004. There are basically two markets for recordable DVD: computer storage and A/V recording. While all of the format developers have focused on providing a single format that will work for both video and computer applications, each DVD format has its strengths and weaknesses Applications All DVD media formats share common parameters for use in a wide range of personal and professional applications. The discs look very similar; however, they do not all work in every DVD drive, DVD-Video player, or DVD recorder. While the DVD formats have important technical differences, Tables 1 and 2 have been developed to help content developers and users determine which media is best for them. General Format Discussion DVD-R, a recordable version of DVD-ROM--The DVD Forum A membership organization devoted to defining DVD standards for read-only, rewritable, write-once, video and audio use. Members participate in working groups to develop new standards. Based in Tokyo, Japan and founded in late 1995 as the DVD Consortium, it was renamed the DVD Forum in 1997. "Minus RW" and "Minus R" are commonly used to refer to the DVD-RW and DVD-R formats of the DVD Forum compared to the DVD+RW Alliance's DVD+RW and DVD+R. For more information, visit www. has developed specifications for two write-once DVD-R categories--Authoring and General use. Although both types of DVD-R media can be read by nearly all DVD drives A Lotta X's This is the label from a Memorex combo DVD and CD drive in 2005. Each "X" number means the speed for that format is X times 1.35MB for DVDs and 150KB for CDs. and players, technical differences make it impossible to write to DVD-R Authoring media using a consumer DVD-R General system and vice versa. DVD-R General recorders use a 650 nm recording laser wavelength while DVD-R Authoring uses a 635 nm laser. In addition, the General Use media contains content protection technology to prevent users from making bit-for-bit copies of CSS- encrypted entertainment titles (Table 3). DVD-R for Authoring was designed to meet the needs of professional content developers and software producers. The media is primarily used to create master discs that will be mass produced by software houses, multimedia/video post-production facilities, and archiving. DVD-R for General Use was developed for business and consumer applications--data archiving and one-time video recording. Delivering 2X write performance, which is equivalent to an 18x CD write speed, the media provides secure recording for volumes of information that cannot be accidentally or intentionally altered. The low storage cost, 100-year data life, and broad compatibility also make DVD-R General media ideal for small-scale distribution of DVD content. DVD-R general discs can be played back by the vast majority of the DVD-ROM drives and video players in use today. Available with street prices as low as $5, the media can be used by DVD-R General drives from Pioneer, Apple, Compaq, Sony, Panasonic, and other leading manufacturers. DVD+R--The write-once DVD+R specification is an extension of the DVD+RW format supported by the DVD+RW alliance: HP, Philips, Ricoh, Sony, Yamaha, Verbatim/ Mitsubishi Chemical, Dell, and Thomson. Similar in functionality and compatibility to DVD-R General, DVD+R was designed to provide widespread playback on DVD-ROM drives and DVD video players. DVD+R/+RW drives write at 2.4x speed, recording a full DVD disc about 5 minutes faster than 2x writers. DVD+R drives and media provide a reliable, low-cost storage solution for archiving home videos, photos, mixed media presentations, and data that require protection from alteration or erasure. Low-cost DVD+R media will be used withDVD+R/+RW drives and video recorders announced by HP, Dell, Philips, Ricoh, and Sony. DVD-RW--DVD-RW is officially referred to as a "re-recordable" format by the DVD Forum, but is commonly known as a rewriteable format. Available with a capacity of 4.7GB, DVD-RW media is recorded sequentially, making it ideal for streaming video applications. DVD-RW media contains protection technology that prevents copying of copy-righted content. Users can write to the disc in multiple sessions as long as the disc has not been finalized, but DVD drives and players can only read DVD-RW media after the disc has been finalized. Currently offering 1x write performance, DVD-RW discs can be overwritten 1,000 times. Most legacy DVD-ROM drives and DVD players, especially those produced in the past two years, will read DVD-RW media. Available at street pricing approaching $10, DVD-RW discs are used by drives and video recorders from Pioneer, Compaq, Sony, and other manufacturers. DVD+RW--Introduced in October 2001, DVD+RW is a rewriteable format developed by the DVD+RW Alliance.Offering 2.4x recording and 1,000 rewrites, the 4.7GB DVD+RW technology is used by consumers for both audio/video and data storage applications. DVD+RW incorporates lossless linking technology, allowing the drive or video recorder to accurately stop and start the writing process, or to replace individual 32kB data blocks. Lossless linking improves compatibility, performance, and ease of use, and permits support of drag-and-drop applications like the Mount Ranier specification (similar to CD-RW functionality). For PC applications, DVD+RW hardware can optionally support CAV CAV - Canine Adenovirus CAV - Cardiac Allograft Vasculopathy CAV - Cavalry CAV - Caveolin CAV - Cavity CAV - Central Africa Vision CAV - Chick Anemia Virus CAV - Collision Avoidance System CAV - Combat Autonomous Vehicle CAV - Command Assault Vehicle CAV - Command Authority Violation CAV - Commercial Asset Visibility CAV - Common Aero Vehicle CAV - Common Aerospace Vehicle CAV - Composite Armored Vehicle CAV - Compound Accreted Value (constant angular velocity) recording to enable fast, random-access reading of the disc. With multi-session writing technology, users who have not finalized the disc can quickly add documents, data, and video segments without having to open and close write sessions. By incorporating the +RW specification for defect management, manufacturers ensure that data is accurately written to and read from the disc. DVD+RW media, which is currently available for $10 to $15, is compatible with +RW drives and video recorders from HP, Philips, Sony, Dell Computer, and other leading manufacturers. DVD-RAM--DVD-RAM (DVD Random Access Memory), the rewriteable format developed by the DVD Forum, provides 100,000 write/rewrite cycles. DVD-RAM features random write/read support, so data, video, and audio can be stored and accessed like a hard drive using standard drag-and-drop techniques. DVD-RAM also offers Defect Sector Management (DSM) to ensure that randomly written data is only placed in usable areas of the media and that data is accurately recovered during the read, write processes. No Finalization is required, so users do not have to open and close write sessions. However, the format specifications that allow these hard-drive like features also renders DVD RAM media incompatible with most DVD-ROM drives and set-top video players. Single-sided (4.7GB) and double-sided (9.4GB) media are available as bare discs or enclosed in a cartridge, with end user pricing ranging from $10 to $35. DVD-RAM discs are used with drives and video recorders from Panasonic, Hitachi, Toshiba, LaCie, QPS, and others. CLV (Constant Linear Velocity) Rotating a disk at varying speeds. By changing speed depending on which track is being accessed, the density of bits in each track can be made uniform. It allows the data transfer rate to be constant and the outer tracks to hold more data than the inner ones. CLV is used on optical media such as CDs and DVDs. In practice, the rotation does not change precisely from every track to the next. vs. CAV Recording Methods When selecting a DVD format, the intended application (computer or AV) and the technology used to carry out the recording process should be considered. Basically, there are two recording methods: Constant Angular Velocity (CAV), which is used in high-speed access applications such as computer storage, and Constant Linear Velocity (storage) constant linear velocity - (CLV) A disk driving scheme in which the linear velocity of the disk is kept constant. This requires that the angular velocity of the disk be larger when the reading or writing tracks closer to the axis. The advantage of this technique is that the read/write speed is constant. However, as mechanical stability puts an upper limit on the angular velocity (and not the linear velocity) using the same linear velocity throughout, i.e. (CLV), which is used in streaming video applications. Most magnetic disk drives use CAV storage, where the drive rotates at a constant rpm (revolutions per minute), no matter what section of the disc is being read. With the ability to provide quick random access, CAV is favored for computer and game read/write storage. The DVD-R and DVD-RW formats use CLV technology, the mode used for the various CD formats and DVD-Video. With CLV, the drive rotates at different rpms, depending on what track of the disc the laser is reading, to maintain a constant data transfer rate. The CLV mode enables higher data transfer rates than CAV, which makes it the preferred recording mode for streaming video, but it slows access when searching for data. DVD-RAM, DVD+RW, and DVD+R offer a combination of recording solutions that make them suitable for both computer and video storage. DVD-RAM discs use Zoned CLV (ZCLV), a combination of CLV and CAV that allows data to be transferred at a variable rate while the drive spins at a constant rate, like a hard disk. The DVD+RW and DVD+R formats utilize sequential CLV recording to provide high data transfer rates and offer CAV as an option when random access is required. Solving Playback Issues Pressed media (DVD-Video, DVD-ROM) is most easily read by all DVD drives and players. Write-once media, DVD-R and DVD+R, is the next most easily read. The rewriteable formats--DVD-RW, DVD+RW, and DVD-RAM--are more difficult to read, but -RW and +RW still have good compatibility because their formats closely resemble that of pressed media. Compatibility problems arise when media does not meet the physical specifications for data format, recording properties, and reflectivity, typically due to poor media manufacturing procedures. When selecting a media brand, users should consider the manufacturer's reputation for quality. Archives of mission-critical information and precious memories deserve the highest quality media. Other problems occur because the player or drive's capabilities and firmware are marginally designed to meet minimum specifications. As DVD format specifications have been finalized, many drive and player manufacturers have enhanced their read mechanisms to improve compatibility with the various media. By making sure that the media has been qualified by the drive manufacturer, users can avoid having to deal with these types of issues. Because DVD format specifications have been finalized at various times since 1997, it is difficult for drive, player, or recorder manufacturers to completely eliminate compatibility issues for Recordable DVD media with all legacy DVD-ROM drives and DVD players. Similar problems existed in the early days of CD-R/RW technology development. Compatibility is improving; and eventually, peripheral manufacturers and users won't have to worry about the compatibility of the recordable DVD format they use to store data, videos, and music. Recognizing that no single format currently offers everything users want, drive manufacturers have introduced combination drives that support both write-once and rewriteable DVD media--DVD-R/-RAM drives, DVD-RW drives, and DVD+R/ +RW drives. By combining a write-once DVD format with a rewriteable DVD format, the drives provide a single solution for sharing and archiving on broadly compatible DVD-R or DVD+R media and the ability to use rewriteable media for files that can be edited and recycled.
Table 1
What Works Where?
DVD Format Typical Supporting
Manufacturers Organization
DVD-R Authoring Pioneer DVD Forum
DVD-R/RW * Pioneer DVD Forum
LaCie
QPS
CD Cyclone
DVD-RW/+R * Ricoh DVD+RW
H-P Alliance (8C)
Philips
Sony
Thompson
DVD-RAM/R Panasonic DVD Forum
Hitachi
LG Electronics
Samsung
LaCie
QPS
DVD SuperMulti * Hitachi DVD Forum
Panasonic
LG Electronics
LaCie
QPS
DVD Multi * LG Electronics DVD Forum
DVD+RW
Alliance
DVD Format Primary Compatible
Application Media
DVD-R Authoring Content DVD-R(A)
Development
DVD-R/RW * Video DVD-R(G)
Development, DVD-RW
archiving
DVD-RW/+R * Computer, DVD-RW
Video DVD+R
DVD-RAM/R Computer, DVD-RAM
Video, DVD-R(G)
Optical Libraries
DVD SuperMulti * Computer, DVD-RAM
Video, DVD-R(G)
Libraries DVD-RW
DVD Multi * Computer, DVD-RAM
Video DVD-R(G)
DVD-RW
DVD+R
* Drives also write all published CD format media
Table 2
DVD Format Feature Comparison
Format Write Read Random Defect Rewrites
Speed Capability Write Mgmt.
DVD-R 2X Excellent No No -0-
DVD+R 2.4X Excellent No No -0-
DVD-RW 1X Good No No 1,000
DVD+RW 2.4X Good Yes Yes 1,000
(as option) (by drive)
DVD-RAM 2X Poor Yes Yes 100,000
(on disc)
Table 3
DVD Media Specifications
DVD-R DVD-R DVD+R
Authoring General 4.7/
9.4GB
Capacity 4.7GB 4.7GR/side 4.7GB
Laser Wavelength 635nm 650nm 650nm
Numerical 0.6 0.6
Aperture
Recording Layer Dye Dye
Reflectivity 45-85% 45-85%
Modulation 0.6 min. 0.6 min.
Amplitude
Data Track Form Wobbled groove + Phase modulated
Land pre-pit wobbled groove
Track Pitch 0.74[micro]m 0.74[micro]m
Tracking Method DPD DPD
(reading)
Min. Pit Length 0.40[micro]m 0.40[micro]m
Data Modulation 8/16, RLL(2,10) 8/16, RLL(2,10)
Error Correction RS-PC RS-PC
Channel Bit Rate 26.16Mbps 26.16Mbps
Scanning Velocity 3.49 m/s 3.49-8.44 m/s
Rewritability N/A N/A
Copy Protection None CSS CSS
DVD-RW DVD+RW DVD-RAM
4.7/9.4GB 4.7/9.4GB
Capacity 4.7GB 4.7GB/side 4.7GB/side
Laser Wavelength 650nm 650nm 650nm
Numerical 0.6 0.65 0.6
Aperture
Recording Layer Phase-Change Phase-Change Phase-Change
Reflectivity 18-30% 18-30% 15-25%
Modulation 0.6 min. 0.6 min. 0.4 min.
Amplitude
Data Track Form Wobbled groove + Phase modulated Wobbled land &
Land pre-pit wobbled groove groove +
Pre-pit
Track Pitch 0.74[micro]m 0.74[micro]m 0.615[micro]m
Tracking Method DPD DPD DPD
(reading)
Min. Pit Length 0.40[micro]m 0.40[micro]m 0.420[micro]m
Data Modulation 8/16, RLL(2,10) 8/16, RLL(2,10) 8/16,
RLL(2,10)
Error Correction RS-PC RS-PC RS-PC
Channel Bit Rate 26.16Mbps 26.16Mbps 58.36Mbps
Scanning Velocity 3.49 m/s 3.49-8.44m/s 8.16-8.49m/s
Rewritability 1,000 1,000 100,000
Copy Protection CSS, CPRM CSS CSS, CPRM
www.verbatim.com Tim Clatterbuck is the product manager of Optical Media at Verbatim Corp. (Charlotte, NC). |
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