In the June issue of EMedia, we reviewed Sony's DRU-700A, the first market-ready double-layer DVD recorder. The drive performed well in testing, producing 8.5GB DVDs on DVD+R DL media without difficulty. The double-layer DVD-Video discs it burned had only one consistent flaw: compatibility with DVD players. Testing in roughly 70 set-top players, portables, DVD-ROM drives, and DVD burners revealed that discs burned in the Sony played in only about 40% of all players tested. (For complete results, see www.emedialive.com/Articles/ReadArticle.aspx?ArticleID=8568.)

In October 2004, Sony's second-generation dual-layer burner, the DRU-710A, arrived at the door of EMedia. The DRU-710A ships with the same Nero recording bundle, and increases DL maximum burn speed to 4X from the previous drive's 2.4X. I replicated the compatibility test as closely as possible to see if improvements to the drive and media had drawn closer to the 90% most DVD+R DL manufacturers claim. I used the same DVD-Video image as in the June review—a DeCSS'd copy of Kill Bill Vol. 1, weighing in at just over 7GB--and burned it to two brands of DL media: Ridata and Verbatim. Then I took the experiment on the road with hopes of improved compatibility results.

I tested playback in several set-top DVD players, portables, ROM drives, and burners found at local Best Buy and Circuit City stores. Results this time showed patterns similar to the previous testing, in terms of what types of devices played the discs successfully, but with an improved rate of compatibility. Over 30 drives were tested, and the 4X Verbatim disc played successfully on 73% of all players and drives, while the 2.4X Ridata media had a 36% success rate (see table for complete results).

Discs burned in the 700A failed to play in any portable DVD players. I found the same trend in this test, but managed to locate one Panasonic portable that played both discs, and a Samsung that played the Verbatim but not the Ridata. The Samsung stalled on the Ridata while playing some of the extra features.

One other key point for analysis is the performance of DVD recorders in reading dual-layer discs. Because recorders do a full disc ID check before playback, they're more likely than set-top players or ROM drives simply to eject the disc. In the June review, this was evident in the 33% playback compatibility rate with DVD±R/RW drives. This time, however, six out of six burners tested played both the Ridata and Verbatim discs.

One way to circumvent some of the compatibility issues with DVD+R DL discs, many have suggested, is to change the discs' Book Type from DVD+R9 to the more familiar ROM. LiteOn, which manufactures the core components of the Sony 700 and 710, offers a Book Type utility that allows you to change the Book Type before recording, but by all appearances, the Sony drive disables that feature. When you open up Nero to burn the disc after running the LiteOn utility, the disc still appears as DVD+R9.

In the end, the Sony second-generation burner showed significant improvement over the first generation in terms of the playback compatibility of DVD+R DL discs burned in the drive. (Whether this improved success rate derives from the media, the drives, the software, or the latest crop of playback devices is unclear, although it's likely a combination of the first three.) The scope of this test was admittedly less broad than in the first review, and tested only what was available in stores. However, the test was thorough enough to give consumers a basic idea of the likelihood that a burned dual-layer disc will play in their homes, and commercial DVD producers an idea of how confident they can be that the DL discs they produce and distribute will play when they reach their end users. 

--Curt Challberg

Company	Model	Type	Verbatim Result	Ridata Result
Sony	DVP-NC665P	ST	YES	NO
Magnavox	MDV456/17	ST	YES	YES
Toshiba	SD 3966	ST	NO	NO
Sony	DVD-N5575P	ST	YES	NO
JVC	XV-NP105L	ST	YES	NO
Sony	DVP-N5775	ST	YES	YES
Samsung	DVD-HD841	ST	YES	NO
Pioneer	DV578A-S	ST	YES	NO
LG	LST-3510	ST	YES	NO
Zenith	XBV443	ST	YES	NO
Toshiba	SD-V592	ST	YES	NO
Samsung	DVD-4800	ST	NO	NO
Toshiba	SD-1800	ST	YES	NO
Toshiba	SD-V392	ST	NO	NO
Sony	SLV-D35OP	ST	YES	NO
Samsung	DVD-V4600	ST	NO	NO
Mitsubishi	DD-6640	ST	YES	NO
Zenith	DVB412	ST	YES	YES
Initial	IDM1731	PP	NO	NO
Insignia	I-PD1020	PP	NO	NO
Liquid Video	LIDM830	PP	NO	NO
Panasonic	DVDLS50	PP	YES	YES
Samsung	DVD-L300	PP	YES	NO
Compaq	SR1210NX	ROM	YES	YES
HP	A700N	ROM	NO	NO
Sony	VGC-RA826G	ROM	YES	YES
Toshiba	M35X5149	ROM	NO	NO
Compaq	SR1230NX	RW	YES	YES
Compaq	R3320US	RW	YES	YES
HP	ZV5330US	RW	YES	YES
HP	A720N	RW	YES	YES
HP	M1160	RW	YES	YES
Sony	VGC-RA826G	RW	YES	YES