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[4.3] What about recordable DVD: DVD-R, DVD-RAM, DVD-RW, DVD+RW, and DVD+R?

There are six recordable versions of DVD: DVD-R for General, DVD-R for Authoring, DVD-RAM, DVD-RW, DVD+RW, and DVD+R. DVD-R and DVD+R can record data once, like CD-R, whereas DVD-RAM, DVD-RW, and DVD+RW can be rewritten thousands of times, like CD-RW. DVD-R was first available in fall 1997. DVD-RAM followed in summer 1998. DVD-RW came out in Japan in December 1999, but was not available in the U.S. until spring 2001. DVD+RW became available in fall 2001. DVD+R was released in mid 2002.

Recordable DVD was first available for use on computers only. Home DVD video recorders (see 1.14) appeared worldwide in 2000. This FAQ uses the terms "drive" or "burner" to refer to recordable computer drives and the term "video recorder" to refer to home set-top recorders.

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. The other two recordable format families (DVD-R/RW and DVD+R/RW) are essentially in competition with each other. The market will determine which of them succeeds or if they end up coexisting or merging.  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 "dash" and "plus" format.

Each writable DVD format is covered briefly below. See section 6.2.3 for hardware manufacturers. For more on writable DVD see Dana Parker's article at <www.emediapro.net/EM1999/parker1.html>. More information on writable DVD formats is available at industry associations: RW Products Promotion Initiative (RWPPI), Recordable DVD Council (RDVDC), and DVD+RW Alliance. Also DVD Writers and DVDplusRW.org. If you're interested in writable DVD for data storage, visit Steve Rothman's DVD-DATA page for FAQ and mailing list info.

[4.3.1] Is it true there are compatibility problems with recordable DVD formats?

Yes. None of the writable formats are fully compatible with each other or even with existing drives and players. In other words, a DVD+R/RW drive can't write a DVD-R or DVD-RW disc, and vice versa (unless it's a combo drive that writes both formats). As time goes by the different formats are becoming more compatible and more intermixed. 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. Some new "super combo" drives can record in both plus and dash 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. There are compatibility lists at CustomFlix, DVDMadeEasy, DVDRHelp, YesVideo.com, HomeMovie.com, and Apple that indicate player compatibility with DVD-R and DVD-RW discs. DVDplusRW.org maintains a list of  DVD+RW compatible players and drives. (Note: test results vary depending on media quality, handling, writing conditions, player tolerances, and so on. The indications of compatibility in these lists are often anecdotal in nature and are only general guidelines.) Very roughly, DVD-R and DVD+R discs work in about 85% of existing drives and players, while DVD-RW and DVD+RW discs work in around 70%. The situation is steadily improving. In another few years compatibility problems will mostly be behind us, just as with CD-R (did you know that early CD-Rs had all kinds of compatibility problems?).

Here is a summary of recordable DVD compatibility. Below each drive is a column indicating how well it can read or write each format (for simplicity, "doesn't write" is implied if not otherwise specified).

[4.3.2] DVD-R

DVD-R (which is pronounced "dash R" not "minus R") uses organic dye technology, like CD-R, and is compatible with most DVD drives and players. First-generation capacity was 3.95 billion bytes, later extended to 4.7 billion bytes. Matching the 4.7G capacity of DVD-ROM was crucial for desktop DVD production. In early 2000 the format was split into an "authoring" version and a "general" version. The general version, intended for home use, writes with a cheaper 650-nm laser, the same as DVD-RAM. DVD-R(A) is intended for professional development and uses a 635-nm 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. The main differences, in addition to recording wavelength, are that DVD-R(G) uses decrementing pre-pit addresses, a pre-stamped (version 1.0) or pre-recorded (version 1.1) control area, CPRM (see 1.11), and allows double-sided discs. A third version for "special authoring," allowing protected movie content to be recorded on DVD-R media, was considered but will probably not happen.

Pioneer released 3.95G DVD-R(A) 1.0 drives in October 1997 (about 6 months late) for $17,000. New 4.7G DVD-R(A) 1.9 drives appeared in limited quantities in May 1999 (about 6 months late) for $5,400. Version 2.0 drives became available in fall 2000. Version 1.9 drives can be upgraded to 2.0 via downloaded software. (This removes the 2,500 hour recording limit.) New 2.0 [4.7G] media (with newer copy protection features), can only be written in 2.0 drives. 1.9 media (and old 1.0 [3.95G] media) can still be written in 2.0 drives. Version 1.0 (3.95G) discs are still available, and can be recorded in Pioneer DVD-R(A) drives. Although 3.95G discs hold less data, they are more compatible with existing players and drives.

Pioneer's DVR-A03 DVD-R(G) drive was released in May 2001 for under $1000. By August it was available for under $700, and by February 2002 it was under $400. The same drive (model DVR-103) was built into certain Apple Macs and Compaq PCs. Many companies now produce DVD-RW drives, all of which write CD-R/RW. As of mid 2002 DVD-RW drives were selling for under $200. Most DVD-RAM drives also write DVD-R discs, some also write DVD-RW discs. Many new drives write both DVD-R/RW and DVD+R/RW.

Pioneer released a professional DVD video recorder in 2002. It sells for about $3000 and provides component video (YPbPr) and 1394 (DV) inputs (along with s-video and composite). It has 1-hour (10 Mbps) and 2-hour (5 Mbps) recording modes, and includes a 2-channel Dolby Digital audio encoder.

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. Blank media are made by CMC Magnetics, Fuji, Hitachi Maxell, Mitsubishi, Mitsui, Pioneer, Ricoh, Ritek, Taiyo Yuden, Sony, TDK, Verbatim, Victor, and others. 

The DVD-R 1.0 format is standardized in ECMA-279. Andy Parsons at Pioneer has written a white paper that explains the differences between DVD-R(G) and DVD-R(A).

It's possible to submit DVD-R(A) and DVD-R(G) discs for replication, with limitations. First, not all replicators will accept submissions on DVD-R. Second, there can be problems with compatibility and data loss when using DVD-R, so it's best to generate a checksum that the replicator can verify. Third, DVD-R does not directly support CSS, regions, and Macrovision. Support for this is being added to DVD-R(A) with the cutting master format (CMF), which stores DDP information in the control area, but it will take a while before many authoring software programs and replicators support CMF.

[4.3.3] DVD-RW

DVD-RW (formerly DVD-R/W and also briefly known as DVD-ER) is a phase-change erasable format. Developed by Pioneer based on DVD-R, using similar track pitch, mark length, and rotation control, DVD-RW is playable in many DVD drives and players. (Some drives and players are confused by DVD-RW media's lower reflectivity into thinking it's a dual-layer disc. In other cases the drive or player doesn't recognize the disc format code and doesn't even try to read the disc. Simple firmware upgrades can solve both problems.) DVD-RW uses groove recording with address info on land areas for synchronization at write time (land data is ignored during reading). Capacity is 4.7 billion bytes. DVD-RW discs can be rewritten about 1,000 times.

In December 1999, Pioneer released DVD-RW home video recorders in Japan. The units cost 250,000 yen (about $2,500) and blank discs cost 3,000 yen (about $30). Since the recorder used the new DVD-VR (video recording) format, the discs wouldn't play in existing players (the discs were physically compatible, but not logically compatible). Recording time varies from 1 hour to 6 hours, depending on quality. A new version of the recorder was later released that also recorded on DVD-R(G) discs and used the DVD-Video format for better compatibility with existing players.

DVD-RW drives write DVD-R, DVD-RW, CD-R, and CD-RW discs. DVD-RW disc prices are around $5-$10 (down from the original $30). Blank media is being made by CMC Magnetics, Hitachi Maxell, Mitsubishi, Mitsui, Pioneer, Ricoh, Ritek, Sony, Taiyo Yuden, TDK, Verbatim, Victor, and others.

There are three kinds of DVD-RW discs. All are 4.7G capacity. Version 1.0 discs, rarely found outside of Japan, have an embossed lead-in (to prevent copying of CSS information), which causes compatibility problems. Version 1.1 discs have a pre-recorded lead-in that improves compatibility. Version 1.1 discs also come in a "B" version that carries a unique ID in the BCA for use with CPRM. B-type discs are required when copying certain kinds of protected video. (See 1.11 for more on CPRM; 3.11 for more on BCA.)

Note: The Apple SuperDrive (even with older 1.22 firmware) can write to DVD-RW discs, but not from the iDVD application. You must use a different software utility, such as Toast, to write to DVD-RW discs.

[4.3.4] DVD-RAM

DVD-RAM, with an initial storage capacity of 2.58 billion bytes, later increased to 4.7, uses phase-change dual (PD) technology with some magneto-optic (MO) features mixed in. DVD-RAM is the best suited of the writable DVD formats for use in computers, because of its defect management and zoned CLV format for rapid access. However, it's not compatible with most drives and players (because of defect management, reflectivity differences, and minor format differences). A wobbled groove is used to provide clocking data, with marks written in both the groove and the land between grooves. The grooves and pre-embossed sector headers are molded into the disc during manufacturing. Single-sided DVD-RAM discs come with or without cartridges. There are two types of cartridges: type 1 is sealed, type 2 allows the disc to be removed. Discs can only be written while in the cartridge. Double-sided DVD-RAM discs were initially available in sealed cartridges only, but now come in removable versions as well. Cartridge dimensions are 124.6 mm x 135.5 mm x 8.0 mm. DVD-RAM can be rewritten more than 100,000 times, and the discs are expected to last at least 30 years.

DVD-RAM 1.0 drives appeared in June 1998 (about 6 months late) for $500 to $800, with blank discs at about $30 for single-sided and $45 for double-sided. The first DVD-ROM drive to read DVD-RAM discs was released by Panasonic in 1999 (SR-8583, 5x DVD-ROM, 32x CD). Hitachi's GD-5000 drive, released in late 1999, also reads DVD-RAM discs. Blank DVD-RAM media is manufactured by CMC Magnetics, Hitachi Maxell, Eastman Kodak, Mitsubishi, Mitsui, Ritek, TDK, and others.

The spec for DVD-RAM version 2.0, with a capacity of 4.7 billion bytes per side, was published in October 1999. The first drives appeared in June 2000 at about the same price as DVD-RAM 1.0 drives. Single-sided discs were priced around $25, and double-sided discs were around $30. Disc prices were under $10 and retail drive prices were under $200 by 2003. DVD-RAM 2.0 also specifies 8-cm discs and cartridges for portable uses such as digital camcorders. Future DVD-RAM discs may use a contrast enhancement layer and a thermal buffer layer to achieve higher density.

Samsung and C-Cube made a technology demonstration (not a product announcement) in October 1999 of a DVD-RAM video recorder using the new DVD-VR format (see DVD-RW section above for more about DVD-VR). Panasonic demonstrated a $3,000 DVD-RAM video recorder at CES in January 2000. It appeared in the U.S. in September for $4,000 (model DMR-E10). At the beginning of 2001, Hitachi and Panasonic released DVD camcorders that use small DVD-RAM discs. The instant access and on-the-fly editing and deleting capabilities of the DVD camcorders are impressive. Panasonic's 2nd-generation DVD-RAM video recorder appeared in October 2001 for $1,500 and also wrote to DVD-R discs.

The DVD-RAM 1.0 format is standardized in ECMA-272 and ECMA-273.

[4.3.4.1] How do I remove a DVD-RAM type 2 disc from the cartridge?

Type 2 DVD-RAM cartridges allow the disc to be removed so that it can be played in standard players or drives. (However, most players and drives still won't be able to read the disc -- see 4.3.1.)

First break (yes, break) the locking pin by pushing on it with a pointed object such as a ballpoint pen. Remove the locking pin. Unlatch the cover by using a pointed object to press the indentation on the back left corner of the cartridge. Data is recorded on the unprinted side of the disc -- do not touch it. When you put the bare disc back the cartridge, make sure the printed side of the shutter and the printed side of the disc face the same direction.

Most DVD-RAM drives will not allow you to write to a bare disc. Some will not allow you to write to a cartridge if the disc has been removed.

[4.3.5] DVD+RW and DVD+R

DVD+RW is an erasable format based on CD-RW technology. It became available in late 2001. DVD+RW is supported by Philips, Sony, Hewlett-Packard, Dell, Ricoh, Yamaha, and others. It is not supported by the DVD Forum (even though most of the DVD+RW companies are members), but the Forum has no power to set standards. DVD+RW drives read DVD-ROMs and CDs, and usually read DVD-Rs and DVD-RWs, but do not read or write DVD-RAM discs. DVD+RW drives also write CD-Rs and CD-RWs. DVD+RW discs, which hold 4.7 billion bytes per side, are readable in many existing DVD-Video players and DVD-ROM drives. (They run into the same reflectivity and disc format recognition problems as DVD-RW.)

DVD+RW backers claimed in 1997 that the format would be used only for computer data, not home video, but this was apparently a smokescreen intended to placate the DVD Forum and competitors. The original 1.0 format, which held 3 billion bytes (2.8 gigabytes) per side and was not compatible with any existing players and drives, was abandoned in late 1999.

The DVD+RW format uses phase-change media with a high-frequency wobbled groove that allows it to eliminate linking sectors. This, plus the option of no defect management, allows DVD+RW discs to be written in a way that is compatible with many existing DVD readers. The DVD+RW specification allows for either CLV format for sequential video access (read at CAV speeds by the drive) or CAV format for random access, but CAV recording is not supported by any current hardware. DVD+R discs can only be recorded in CLV mode. Only CLV-formatted discs can be read in standard DVD drives and players. DVD+RW media can be rewritten about 1,000 times (down from 100,000 times in the original 1.0 version).

DVD+R is a write-once variation of DVD+RW, which appeared in mid 2002. It's a dye-based medium, like DVD-R, so it has similar compatibility as DVD-R. Original DVD+RW drives did not fulfill the promise of a simple upgrade to add DVD+R writing support, so they have to be replaced with newer models. The original Philips DVD+RW video recorders, on the other hand, can be customer-upgraded to write +R discs.

Philips announced a DVD+RW home video recorder for late 2001. The Philips recorder uses the DVD-Video format, so discs play in many existing players. HP announced a $600 DVD+RW drive (made by Ricoh) and $16 DVD+RW discs for September 2001. HP's drive reads DVDs at 8x and CDs at 32x, and writes to DVD+RW at 2.4x, CD-R at 12x, and CD-RW at 10x.

In 2003 DVD+R discs cost around $2 to $6 and DVD+RW discs cost around $5 to $10. DVD+RW media is produced by CMC Magnetics, Hewlett-Packard, MCC/Verbatim, Memorex, Mitsubishi, Optodisc, Philips, Ricoh, Ritek, and Sony.

More DVD+RW information is at www.dvdrw.com and www.dvdplusrw.org. The obsolete DVD+RW 1.0 format is standardized in ECMA-274.

[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 also 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, whereas DVD+RW drives only record on +R and +RW discs, so you have to make sure you get the right kind of blank discs. There's also a concern that one of the formats could "win" and the other format could disappear, leaving you with abandoned hardware. This is not very likely, since both formats are doing well. 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. Combo 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, 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.

[4.3.7] Other recordable optical formats

Competitors to recordable DVD were announced but never appeared, thanks in part to the success of the entire DVD family. These formats included AS-MO (formerly MO7), which was to hold 5 to 6 billion bytes, and NEC's Multimedia Video Disc (MVDisc, formerly MMVF, Multimedia Video File), which was to hold 5.2 billion bytes and was targeted at home recording. ASMO drives were expected to read DVD-ROM and compatible writable formats, but not DVD-RAM. MVDisc was similar to DVD-RW and DVD+RW, using two bonded 0.6mm phase-change substrates, land and groove recording, and a 640nm laser, but contrary to initial reports, the drives were not expected to be able to read DVD-ROM or compatible discs.

There was also FMD (see 2.13). And there are HD formats (see 6.5).

[4.3.8] How long does DVD recording take?

The time it takes to burn a DVD depends on the speed of the recorder and the amount of data. Playing time of the video may have little to do with recording time, since a half hour at high data rates can take more space than an hour at low data rates. A 2x recorder, running at 22 Mbps, can write a full 4.7G DVD in about 30 minutes. A 4x recorder can do it in about 15 minutes.

Note that the -R/RW format often writes a full lead-out to the diameter required by the DVD spec, so small amounts of data (like a very short video clip) may take the same amount of time as large amounts.

This FAQ is written and maintained by Jim Taylor. The following people contributed to early versions of the DVD FAQ. Their contributions are deeply appreciated. Information has also been taken from material distributed at the April 1996 DVD Forum, May 1997 DVD-R/DVD-RAM Conference, and October 1998 DVD Forum Conference.

Robert Lundemo Aas
Adam Barratt
David Boulet
Espen Braathen
Wayne Bundrick
Irek Defee
Roger Dressler
Chad Fogg
Dwayne Fujima
Robert "Obi" George
Henrik "Leopold" Herranen
Kilroy Hughes
Mark Johnson
Ralph LaBarge
Martin Leese
Dana Parker
Eric Smith
Steve Tannehill
Geoffrey Tully

Thanks to Videodiscovery for hosting this FAQ for the first two and a half years.