Recordable/Rewritable DVD Media

An Introduction to the Topic
There several different types of recordable and rewritable DVD media and, as you might expect, not all of them use the same method of writing to the disc. DVD-R uses the same organic dye technology as CD-R media. As we noted in our CD-R report, When you record onto DVD-R media, a laser in the recorder burns spots into a layer of dye on the underside of the disc. The resulting dark spots are then read by a different, lower-power laser in the playback unit, which alternately detects the dark spots and bright areas, where the laser reflects off the shiny surface of the disc.

As is the case with CD-R media, there are a number of factors that contribute to reliability of DVD-R media.

These include:

1. The density and evenness with with the dye is applied, the conditions in which the disc is stored (cool, dark locations with low humidity are best). In some cases, defective media will result in what is known as a "hard error" on the disc.
2. The brand and condition of your DVD recorder and the playback drive. Different drives have differing abilities to read the darkened spots that their write-mode laser has etched into the disc. Some DVD players (typically, very old ones) are physically incapable of reading discs produced by certain recorders, no matter what brand of media is used.
3. Further complicating the issue, some discs have dark dyes that aren't read well by the read-mode lasers of some players; other discs -- often these with a silver surface -- are quite the opposite: they are too shiny to be reliably read. Indeed, some brands of DVD recorders work fine with a type of media that is useless in a different recorder.

DVD-RW, however, is quite different. It is known as a phase-change erasable format. The discs have lower reflectivity than DVD-R discs, causing DVD-RW to be compatible with a narrower range of players. DVD-RW discs can be rewritten about 1,000 times.

DVD-RAM media, according to DVD Demystified, uses phase-change dual (PD) technology "with some magneto-optic (MO) features mixed in." DVD-RAM can be rewritten more than 100,000 times, and the discs are expected to last at least 30 years.

DVD+RW is an erasable format based on CD-RW technology and has roughly the same compatibility caveats as DVD-RW. DVD+RW media can be rewritten about 1,000 times.

Video Professionals Speak
The best exploration of the question of reliability we've seen appeared in the German magazine C'T. A forum posting at CDFreaks.com has an English-language summary. Here's an excerpt:

• None of the tested media met all specs
• Ricoh DVD+R media can be anything from [crap] to [great]; there's no chance to find out unless you have non-standard equipment
• The only good DVD-R media are the ones that are 2x certified for DVR-A03, no other media had an acceptable PI sum8 error rate even at 1x (except Optodisc and Digital Disc Dessau, both of which bordered the acceptable). Taiyo Yuden media was not included in the test.
• the tracking signal of good DVD+R was better than of good DVD-R.
• error rates on good DVD-R media were lower than on good DVD+R media (=Mitsubishi only!), but low enough to give a "very good" for Mitsubishi both DVD±R as to error rates.
• the worst DVD-R media in the test was CMC, with error rates 2x as high as on the worst DVD+R test disc (made by Ricoh!)
• crap media:  Princo, Vivastar, some Ritek, CMC, some Ricoh.
• DVD+R defines a max PIF rate of 4, while DVD-R has no spec as to PIF. Ironically, the only media that stayed below that were Pioneer DVD-R and Maxell DVD-R (no, neither TDK nor Verbatim did)
• only Ritek, CMC and Ricoh media contained POFs (=hard read errors)
• Mitsubishi 4x DVD-R media (beta-state!) already has error rates that meet the specs.

Elsewhere, a report on DVD problems at MacInTouch.com notes that some DVD players are better able to handle 2x media when it is recorded at the slower 1x speed. It also discusses other potential issues that may affect reliability, such as unbalanced discs due to misaligned labels, dust, scratches, smoke residue, etc.

LaCie recommends Verbatim or Apple-branded media for use with its (Pioneer 104/105-based) drives.

The FAQ at Roxio.com claims that "early 2x SuperDrives had problems with Mitsui and Maxell 2x media." Users report better success with 4x Verbatim and Pioneer media and even the extremely inexpensive Optodisc media, which sells for a fraction of the cost of Apple-branded media.

Note, however, that early SuperDrives (e.g., Pioneer 103 and 104 drives) required their firmware to be updated before 4x media can be used -- and after doing so, the drives write to these "high speed" discs at a mere 1x speed. (The Firmware Bugs section of our SuperDrive report, elsewhere on this site, has details.)

DVD-R versus DVD+R
CDR-Info tested over 1,000 combinations of drive, media and player to determine the best possible level of compatibility. It tested eight brands of media (two examples of each media type) using five different recorders, then tested readability of the resulting discs in twenty-seven standalone DVD players and twenty DVD-ROM drives. The result: DVD-R is clearly the most compatible DVD recording format on the market. To assess the compatibility level of DVD formats, CDR-Info created video content on a DVD writer using DVD-R/RW and +R/RW media. These discs were then played back in other DVD players and DVD-ROM drives. Slashdot has further details.

Similar results can be seen at dvdrhelp.com, where end users report their own compatibility findings. At this writing, the results stack up as follows:

DVD-R: 90% support, 10% do not
DVD+R: 85% support, 15% do not

DVD-RW: 74% support, 26% do not
DVD+RW: 74% support, 26% do not

You can check your own player’s compatibility against the site's database of reports. (A similar database for Mac users is available at http://www.xlr8yourmac.com.)

We welcome your comments and success stories.