12.2 DVD Writable and Rewritable

In addition to DVD-ROM, there are three writable DVD formats?DVD-R(A) for authoring, DVD-R(G) for general recording, and DVD+R?and three rewritable DVD formats?DVD-RW, DVD-RAM, and DVD+RW. All DVD writers and rewriters can read DVD-ROM discs, but each records to its own type of disc, none of which is fully compatible with any other or with existing standard DVD-ROM drives and players.

Incompatibility between the various standards has hindered the market acceptance of all of them, a problem that manufacturers have begun to address by introducing hybrid devices that read and write more than one format. For example, Pioneer produces a combination DVD-R and DVD-RW drive that also writes CD-R and CD-RW, and next-generation DVD-RAM drives will read and write DVD-RAM, DVD-R(W), and CD-R(W). As time passes, we expect this trend to continue.

The DVD Forum has introduced a DVD Multi logo that certifies compatibility with DVD-R, DVD-RW, and DVD-RAM (although not with DVD+RW?the DVD Forum and the DVD+RW Alliance don't much like each other). A DVD Multi drive or player can play all three formats, and a DVD Multi writer can write all three formats.

The following sections describe the competing writable/rewritable DVD formats.

12.2.1 DVD-R

DVD-R (Recordable) was the first recordable DVD standard. DVD-R uses organic dye technology, and is similar conceptually to CD-R. DVD-R discs can be read by most DVD-ROM drives and DVD players. DVD-R 1.0 drives shipped in late 1997, cost $17,000, and stored 3.95 GB on a write-once DVD-R 1.0 disc, which at the time cost $80 each. TheDVD-R 1.0 standard is specified by ECMA-279 (http://www.ecma-international.org/publications/standards/ECMA-279.HTM). DVD-R 1.9 drives shipped in mid-1999, cost $5,000, stored 4.7 GB on a write-once DVD-R 1.9 disc (which at the time cost $50 each), and could also write 3.95 GB 1.0 discs. DVD-R 2.0 drives shipped in late 2000, store 4.7 GB on write-once 2.0 discs (which are copy-protected), and can also write 1.0 and 1.9 discs. DVD-R branched into two subformats in early 2000:

DVD-R(A): DVD-R(A) (DVD-R Authoring) drives are for professional use, and use a 635 nm laser which can write DVD-R(A) discs, but not DVD-R(G) discs. DVD-R(A) drives can read either type of DVD-R disc, as can most DVD drives and DVD players. DVD-R(A) drives sell for $1,500 to $5,000, and DVD-R(A) discs cost roughly twice what DVD-R(G) discs cost.
DVD-R(G): DVD-R(G) (DVD-R General) drives are for home use, are particularly suited to video recording, and use a 650 nm laser that can also write DVD-RAM discs, although as of July 2003 only Panasonic has shipped combination DVD-R(G)/DVD-RAM drives. DVD-R(G) drives can use double-sided discs and incorporate CPRM (Content Protection for Removable Media) copy protection, which means that DVD-R(G) drives cannot be used legally to duplicate DVD-Video discs.

According to various figures we have seen, DVD-R discs can be read by roughly 85% of older DVD-ROM drives and DVD players.

12.2.2 DVD-RW

DVD-RW (Rewritable) is a newer Pioneer technology, based on DVD-R but using phase-change erasable media similar conceptually to CD-RW. DVD-RW was formerly called DVD-ER and DVD-R/W before Pioneer settled on the DVD-RW designation. Like DVD-R, DVD-RW stores 4.7 GB per disc and produces discs readable by many DVD-ROM drives and players, although the lower reflectivity of DVD-RW discs fools some DVD-ROM players into thinking they're reading a dual-layer disc. DVD-RW discs can be read by about 65% of older DVD-ROM drives and DVD players. Recent DVD-ROM drives or players that have difficulty with DVD-RW discs can often be upgraded to support DVD-RW simply by installing updated firmware.

There are three distinct types of DVD-RW discs, all of which store 4.7 GB and can be rewritten about 1,000 times:

DVD-RW 1.0: DVD-RW 1.0 discs were used with the first DVD-RW drives shipped in Japan, are seldom seen outside Japan, and have compatibility problems with some drives.
DVD-RW 1.1: DVD-RW 1.1 discs do not support CPRM and so cannot be used for copying any CPRM-protected original DVDs.
DVD-RW 1.1B: DVD-RW 1.1B discs support CPRM, and can be used to copy CPRM-protected original DVDs (but only if the producer of the original DVD has encoded the disc to permit copying, and only then by adhering to the restrictions enforced by the CPRM encoding on the original disc). In effect, this means that commercial DVD movies cannot be copied on a DVD-RW drive other than by using special software?the use or even possession of which is illegal in some jurisdictions?to bypass the copy protection.

In April 2001, Pioneer began shipping the sub-$1,000 DVR-A03 drive, which despite its name writes DVD-R(G) discs rather than DVD-R(A) discs. In addition to DVD-R(G) discs, the DVD-A03 writes DVD-RW, CD-R, and CD-RW, and by March 2002 had dropped to a street price of about $500. Apple and Compaq bundled relabeled DVR-A03 drives with some Mac and Presario models, which greatly contributed to the popularity of DVD-R. Pioneer soon followed with the DVR-A04 drive and then the DVD-A05 drive, which doubled write speeds to 4X DVD-R, 2X DVD-RW.

Using 4X DVD-R discs or 2X DVD-RW discs in an older recorder may destroy both the disc and the recorder unless you update the drive firmware before using the newer discs. This problem arises because older recorders do not recognize the newer high-speed discs. In attempting to determine media type, the drive turns on its laser and keeps it on in an endless loop, destroying the disc and burning out the laser. Updating the drive firmware prevents damage to your disc or drive. Pioneer DVR-A03, DVR-103, DVR-A04, and DVR-104 drives are affected, as well as relabeled OEM drives and some standalone recorders produced by Pioneer. Visit http://www.pioneerelectronics.com/hs/ for more details.

Excluding licensing costs, DVD-R(W) drives and discs are inherently no more costly to produce than CD-R(W), so it is possible that the broad-based support garnered by DVD-R(W) will reduce the price of drives and media dramatically, making DVD-R (and particularly DVD-RW) a viable competitor with other recordable DVD standards. As of July 2003, DVD-R(G) disks sold for $0.75 to $4 each, depending on disc quality and packaging, and DVD-RW discs for $1.25 to $5.50 each.

Pure DVD-R(W) drives remain the almost exclusive preserve of Pioneer, although repackagers such as QPS sell DVD-R(W) drives under their own labels and other manufacturers such as Sony produce hybrid DVD-RW/DVD+RW drives that can write DVD-R and DVD-RW discs. DVD-R(W) has the advantages of wide distribution, the best suitability for recording video, and the highest compatibility with older DVD-ROM drives and players. Against those advantages, it must be said that DVD-R(W) is the least suitable of the competing technologies for storing data, and therefore the least-appropriate choice for a general-purpose PC DVD writer.

12.2.3 DVD-RAM

The DVD-RAM standard is backed by Hitachi, Matsushita (Panasonic), and Toshiba, which until late 2001 had the writable DVD market all to themselves. Although DVD-RW and DVD+RW drives became widely available from several vendors by late 2001, relative to those writable DVD standards, DVD-RAM has several advantages for use in computers, including superior defect management, use of zoned CLV (PCAV) for faster access, and greater media protection via a cartridge. A DVD-RAM disc can be rewritten at least 100,000 times. Alas, only a tiny percentage of older DVD-ROM drives and almost no DVD players can read DVD-RAM discs.

First-generation (DVD-RAM Book 1.0) DVD-RAM drives began shipping in mid-1998, and used a mix of phase-change and magneto-optical technology to record 2.58 billion bytes per side on rewritable media. These discs are not readable by older DVD players and drives, although some recent DVD-ROM drives will read them. Second-generation (DVD-RAM Book 2.1) DVD-RAM drives, which began shipping in late 2000, read and write both original 2.6/5.2 GB DVD-RAM discs and 4.7/9.4 GB DVD-RAM discs.

Several DVD-RAM media types are available. Single-sided 2.6 GB discs are available in Type 1 (sealed) or Type 2 (removable) cartridges. Single-sided 4.7 GB discs are available in Type 2 cartridges. Double-sided 5.2 GB and 9.4 GB discs were originally available only in Type 1 cartridges, but are now available in Type 2 cartridges as well. In late 2002, noncartridge 4.7 GB and 9.4 GB DVD-RAM discs became widely available. These bare discs can be reliably written and rewritten in DVD-RAM drives designed to accept them, but many older DVD-RAM drives simply refuse to write them.

Although a cartridge is advantageous for computer use, a cartridge raises two issues. First, because standard DVD players and drives cannot physically accommodate a cartridge, DVD-RAM discs enclosed in cartridges cannot be read on these devices. Second, once removed from their cartridges, DVD-RAM discs may no longer be reliably recorded in some drives, particularly older models, so removing discs from their cartridges may effectively turn them into write-once media. Most older DVD-RAM drives will not write reliably (if at all) to a bare disc, but recent DVD-RAM drives generally write reliably to a noncartridge disc or to a disc that has been removed from and then reinstalled in its cartridge.

DVD-RAM 1.0 (2.6/5.2 GB) standards are specified by ECMA-272 (http://www.ecma-international.org/publications/standards/ECMA-272.HTM) and ECMA-273 (http://www.ecma-international.org/publications/standards/ECMA-273.HTM, released in June 1999 and February 1998, respectively. DVD-RAM 2.0 (4.7/9.4 GB) standards are specified by ECMA-330 (http://www.ecma-international.org/publications/standards/ECMA-330.HTM) and ECMA-331 (http://www.ecma-international.org/publications/standards/ECMA-331.HTM), both released in December 2001.

Superior defect mapping and other technical considerations make DVD-RAM the best choice for recording data, but its limited compatibility with older DVD-ROM drives and players makes it a poor choice for recording video. If you need a DVD writer solely to back up or archive computer data, DVD-RAM may be the best choice, although DVD-RAM discs cost more than DVD-R(W) and DVD+R(W) discs, and the write speed of DVD-RAM drives is much lower than that of DVD-RW and DVD+RW drives. If you need to record video to be played back on standard DVD-ROM drives or players, choose another technology.

12.2.4 DVD+RW

Originally called DVD+RW, changed to +RW when the DVD Forum objected, and later changed back, DVD+RW is backed by Hewlett-Packard, Mitsubishi Chemical, Philips, Ricoh, Sony, Thomson Multimedia, and Yamaha. Although all are members of the DVD Forum, the DVD+RW standard is not recognized by that organization. First-generation DVD+RW drives were to use phase-change rewritable technology to store 2.8 GB per side. DVD+RW manufacturers formally abandoned the 2.8 GB DVD+RW 1.0 standard in late 1999, without ever having produced drives in commercial numbers. Second-generation DVD+RW drives, which finally shipped in volume in late 2001, expand capacity to 4.7 GB per side and support writing CD-R and CD-RW discs. DVD+RW discs are readable by most recent DVD players and DVD-ROM drives, although as with DVD-RW the lower reflectivity of DVD+RW discs causes some devices to mistake them for dual-layer DVD-ROM discs and therefore refuse to read them. A firmware update solves that problem in many drives and players that experience it. Roughly 65% of older DVD-ROM drives and DVD players can read DVD+RW discs.

DVD+RW backers claim two primary advantages for DVD+RW relative to DVD-RAM. First, like CDs, DVD+RW discs do not use a cartridge (although non-cartridge DVD-RAM discs are now available). This translates into lower costs for drives and media, and allows DVD+RW discs to physically fit standard drives. It also makes DVD+RW drives a viable alternative for laptop systems, which cartridge-based DVD-RAM drives are not. Second, DVD+RW drives use CLV access for sequential data (such as movies) and CAV access for random data, which allows higher performance. Balanced against this is the fact that DVD+RW discs can be rewritten only 1,000 times, versus 100,000 for DVD-RAM.

The obsolete and abandoned +RW standard is specified by ECMA-274 (http://www.ecma-international.org/publications/standards/ECMA-274.HTM). The current DVD+RW standards are maintained by the DVD+RW Alliance (http://www.dvdrw.com) and as ECMA-337 (http://www.ecma-international.org/publications/standards/ECMA-337.HTM). Another good (albeit unofficial) source for DVD+RW information is http://www.dvdplusrw.org.

12.2.5 DVD+R

The first DVD+RW drives could use only rewritable DVD+RW discs. CD-R remains popular despite the availability of rewritable CD-RW discs, and it was clear to DVD+RW supporters that a write-once version of DVD+RW would fill an important niche. The write-once version of DVD+RW, as you might expect, is called DVD+R. DVD+R provides the equivalent of a 4.7 GB CD-R disc. Roughly 85% of older DVD-ROM drives and DVD players read DVD+R discs, which is to say they have about the same level of compatibility as DVD-R discs.

DVD+R discs began shipping in mid-2002, and a firestorm erupted almost immediately. Some DVD+RW drive makers had preannounced the availability of DVD+R discs and had told buyers of first-generation DVD+RW drives that a simple firmware update would allow the drives to use DVD+R discs as well. That turned out not to be the case, and buyers of early DVD+RW drives learned that the only way to add DVD+R support was to replace their drives. Current DVD+RW drives support DVD+R and DVD+RW discs interchangeably. Like CD-R and DVD-R before it, DVD+R discs use organic dye technology, so nothing other than patent royalties prevents DVD+R (and DVD-R) discs from eventually falling to prices nearly as low as CD-R discs.

12.2.6 Writable DVD Formats Compared

It's clear that the competition to become the mass-market writable DVD standard is a three-horse race, but it is uncertain which will ultimately triumph. In the first edition of this book, we noted that the market had not yet determined a winner in the writable DVD format wars and that we hoped a single standard would prevail by the time the second edition was published. We said the same thing in the second edition, and now we're forced to say the same in the third.

Perhaps by the time the fourth edition is published we'll finally have a single standard. But we won't hold our breath. The issue is the huge amount of money at stake. If one standard prevails, DVD writers will become as commonplace as CD writers are now, and DVD blanks will sell by the billion. The company or consortium that holds the patents on the winning standard will rake in huge amounts in licensing fees for drives and discs. That means the companies involved aren't going to compromise, and the only hope for achieving a single standard is that the market will sort things out.

DVD-R and DVD-RW

These formats have the strong backing of Pioneer and Apple and the increasing popularity of home video editing to sustain them. DVD-R and DVD-RW discs are inexpensive (and getting cheaper every month) and readily available. Current drives write DVR-R discs at 4X, which matches DVD+R, and DVD-RW discs at 2X, versus the 4X write speed of DVD+RW. For the time being, DVD-R/RW discs are cheaper than DVD+R/RW discs, although we expect that to change as DVR+R/RW drives continue to gain market share.

DVD-R is an excellent choice for recording video because it offers very high compatibility with older DVD-ROM drives and DVD players. DVD-R(G) and DVD-RW are not the best choice for recording data because the DVD-R(W) format lacks defect mapping support (although new-generation drives may support Mt. Rainier, which implements defect mapping in drive hardware). DVD-RW is the least-desirable rewritable standard because its sequential access method prevents incremental rewrites.

Because of the high price of drives and discs, DVD-R(A) is and is likely to remain a niche product, of interest primarily to professional video producers.

DVD-RAM

DVD-RAM has been shipping since 1998, is an official standard of the DVD Forum, is backed by Hitachi, Panasonic, and Toshiba, and has distinct advantages for recording data. Despite these advantages, various industry pundits including John Dvorak have declared DVD-RAM dead. We suspect that DVD-RAM, like Mark Twain, finds the rumors of its death to be greatly exaggerated. Without question, DVD-RAM suffers several disadvantages relative to DVD-RW and DVD+RW. DVD-RAM discs can be read by relatively few DVD-ROM drives and by almost no DVD players. DVD-RAM discs cost more than DVD-RW or DVD+RW discs. Finally, DVD-RAM is slow. Whereas DVD+RW rewrites at 4X and DVD-RW at 2X, DVD-RAM rewrites at just 1X, and that's with write verification turned off. Turning on write verification slows DVD-RAM writes to a snail-like 0.5X.

So why would anyone use DVD-RAM? Reliability, pure and simple. When we write 4.7 GB of data to an optical disc, we want some reasonable assurance that we will later be able to read every bit of that data without error. The defect mapping and robust error detection and correction of the DVD-RAM format provide a level of assurance that other rewritable formats do not.

DVD+RW and DVD+R

DVD+RW and DVD+R are not recognized by the DVD Forum, but are backed by the DVD+RW Alliance, which comprises, among others, Dell, HP, Mitsubishi/Verbatim, Philips, Ricoh, Sony, Thomson, and Yamaha. Second- and third-generation DVD+RW drives write DVD+R discs at 4X and rewrite DVD+RW discs at 2.4X or 4X. DVD+R discs are compatible with roughly 85% of older DVD-ROM drives and DVD players, which is comparable to DVD-R compatibility. DVD+RW discs are compatible with about 65% of older drives and players, which again is comparable to DVD-RW compatibility.

Relative to DVD-RAM drives, DVD+RW drives offer much higher speed at the expense of less-robust error detection and correction. Relative to DVD-RW drives, DVD+RW drives offer the following advantages:

Higher rewrite speeds

Current DVD+R and DVD+RW drives write high-speed discs at 4X, versus DVD-R 4X writes and DVD-RW 2X writes.

Although 2.4X DVD+RW drives were not designed to use 4X discs, many such drives can use 4X discs if you upgrade the firmware.

Superior error detection and correction

Although DVD-RAM provides the best error detection and correction, current DVD+RW drives provide error detection and correction superior to DVD-RW drives, which do not support hardware defect management. The defect management used by DVD+RW drives is invisible to standard DVD-ROM drives and DVD players.

Lossless linking

DVD+RW drives support lossless linking, which means they can rewrite any individual sector of a DVD+RW disc directly, while maintaining compatibility with DVD-ROM drives and DVD players. Lossless linking also enables packet writing and Mt. Rainier (EasyWrite) support. Conversely, making a change to a DVD-RW disc requires rewriting the entire disc.

Background formatting

DVD-RW and DVD+RW discs must be formatted before they can be written to. The difference is that DVD-RW drives format discs in the foreground, which may take an hour to complete in a 1X drive. DVD+RW drives format discs in the background. After formatting the lead-in and a portion of the data area, which requires only a minute or so, a DVD+RW drive can immediately begin writing data to the disc as formatting continues in the background. A partially formatted disc can be ejected at any time and can be read by a standard DVD-ROM drive. When you reinsert the disc in the DVD+RW drive, formatting recommences and continues until completion.

DVD+VR support

DVD+RW drives support the DVD+VR video format, which allows editing a video disc while maintaining compatibility with DVD players. Conversely, the VR format used by DVD-RW drives requires rewriting the entire disc if you make even a minor change.

Here's our take on the competition. For backing up or archiving computer data, the best choice is a DVD-RAM drive. For general-purpose DVD writing, the best choice is a DVD+R/RW drive or a hybrid drive that can write DVD-R, DVD-RW, DVD+R, and DVD+RW. Such drives are often called DVD±RW drives (pronounced DVD-plus-or-minus-RW), an unofficial but useful designation that probably annoys both the DVD Forum and the DVD+RW Alliance. DVD±RW drives can write any DVD blank except DVD-RAM, which allows you to choose media type by price and suitability for the intended use. DVD+R and DVD-R blanks are fine for recording video, and DVD+RW blanks are usable (if not ideal) for backing up and archiving data.

All these technologies are legally useless for duplicating DVD-Video discs (although very few technical hurdles exist and many people already do it on a regular basis). Laws such as the Digital Millennium Copyright Act (DMCA) and standards such as CPRM have effectively eliminated Fair Use provisions of traditional copyright. You can use these drives to store data or video that you have produced, but not as a digital VCR or to back up your DVD-Video discs, at least without breaking the law. Movie industry lobbyists are fighting desperately to make sure you don't have that option.

12.2.7 Read/Write Compatibility

Table 12-2 lists read/write compatibility between various types of DVD drives with CD and DVD media. Drives are in the heading row; media types are in the left column. The first circle indicates read compatibility and the second write compatibility. An asterisk on either or both sides of the slash means some but not all drive models of that type read and/or write the media type in question, possibly with limitations, which may be drive- or media-specific. For example, only some recent DVD-ROM drives can read DVD-RAM media, and some DVD-ROM drives cannot read DVD-RW media because they mistake them for dual-layer DVD-ROM discs.

Table 12-2. Drive and media read/write compatibility
	DVD-ROM	DVD-R(A)	DVD-R(G)	DVD-RW	DVD-RAM	DVD+RW
CD-DA	/ --	/ --	/ --	/ --	/ --	/ --
CD-ROM	/ --	/ --	/ --	/ --	/ --	/ --
CD-R	/ --	/ --	/ --	/ --	/ --	/ --
CD-RW	/ --	/ --	/ --	/ --	/ --	/ --
DVD Video	/ --	/ --	/ --	/ --	/ --	/ --
DVD-ROM	/ --	/ --	/ --	/ --	/ --	/ --
DVD-R(A)	* / --	/	/ --	/ --	/ --	/ --
DVD-R(G)	* / --	/ --	/	/ *	/ --	/ --
DVD-RW	* / --	/ --	/ --	/	* / --	* / --
DVD-RAM	* / --	-- / --	-- / --	-- / --	/	-- / --
DVD+RW	* / --	* / --	* / --	* / --	* / --	/
DVD+R	* / --	* / --	* / --	* / --	* / --	/

Compatibility may vary by drive manufacturer. For example, a DVD-ROM drive made by a member of the DVD-RAM group may read DVD-RAM discs, but is unlikely to read DVD+RW discs. Conversely, a DVD-ROM drive made by a member of the DVD+RW group may read DVD+RW discs, but is unlikely to read DVD-RAM discs.

12.2.8 Choosing a Writable DVD Drive

You take a risk no matter which of the three competing technologies you choose. Whichever you buy, there's a chance it will be orphaned if the market chooses one of the others. So which of these drives should you buy?

If you need reliable, high-capacity optical storage for data, get a DVD-RAM drive. A DVD-RAM drive is slower than the alternatives and won't write CD-R or CD-RW, but has very reliable error correction. DVD-RAM is suitable if the drive and the data it stores will be used on one computer, or if you need to transfer large amounts of data between computers that all have DVD-RAM drives. Other than performance and higher media cost, the chief drawback of DVD-RAM is that DVD-RAM discs are incompatible with many DVD-ROM drives and DVD players. In short, DVD-RAM is the most reliable of the competing formats for storing large amounts of data, but is the best choice only if high write speeds are unimportant and you will never need to read the DVD-RAM discs in a system without a DVD-RAM drive.
If you need a general-purpose DVD writer, get a DVD+R/RW drive or a hybrid DVD+/-RW drive. These drives can write any DVD blank except a DVD-RAM disc, and most can write CD-R and CD-RW discs as well. DVD+/-RW drives offer the best combination of flexibility and reliability for most users. They produce discs that are readable by most DVD-ROM drives and DVD players, and write discs as fast or faster than competing single-standard drives. They are ideal for writing video discs, and a reasonable choice for backing up and archiving data.
We consider single-standard DVD-R/RW drives undesirable because they limit your choice of media. In particular, we recommend against a DVD-RW drive no matter how low the price unless you are certain you will never use the drive for anything except recording video to DVD-R discs. In our opinion, DVD-RW compares poorly to DVD+RW for most purposes, so it makes little sense to saddle yourself with what amounts to a dedicated DVD-R video writer.
A single-standard DVD+R/RW drive is a much better choice. It writes DVD+R discs, which are as useful for video as DVD-R discs, and also supports the superior DVD+RW rewritable format. Choosing a DVD+R/RW drive means you can't write DVD-R/RW discs, which for now cost a bit less than DVD+R/RW discs, but a single-standard DVD+R/RW drive costs $50 to $150 less than a hybrid drive of equal quality.

Although it's still too soon to declare a winner in the writable DVD format wars, as of July 2003 we think DVD+R/RW is the leading candidate. DVD-RAM cannot compete as a mainstream writable DVD format, although it remains the safest format for archiving data. The only advantage that DVD-R/RW has relative to DVD+R/RW is somewhat lower media cost, and that disparity is disappearing quickly. We expect that discs for either format will soon sell at comparable prices. If that comes to pass, DVD-R/RW will simply fade away.