The DVD Forum released a notification today for the companies engaged in manufacturing of Dual Layer DVD-RW discs, about the compatibility of the new media with currently available players/burners.
The DVD Forum approved the DVD specifications for Re-recordable Disc for Dual Layer (DVD-RW for DL) (Part 1 PHYSICAL SPECIFICATIONS Version 2.0) in September 2006. The new disc offers a capacity of 8.54GB per side for a 12cm disc and a 2.66GB per side for an 8cm disc. According to the DVD Forum. the new Ver.2.0 discs should only be used with hardware which conforms to Ver.2.0, and not with hardware which conforms to the previous versions of DVD Re-recordable media, currently available on the market (Ver.1.0, Ver.1.1 or Ver.1.2).
The Non-Ver.2.0 hardware cannot record any data onto a Ver.2.0 Disc. When Non-Ver.2.0 hardware tries to record data onto Ver.2.0 Disc, the disc cannot be recognized as usable media. Moreover, such improper use of a Ver.2.0 Disc with Non-Ver.2.0 hardware may result in damage to the disc surface and/or the data recorded on the Ver.2.0 Disc.
In addition, the new DVD-RW DL media are not readable with Non-Ver.2.0 hardware.
In general, the compatibility of the new DVD-RW DL media could be achieved with some modifications made on the playback devices. In the table below you can see the main parameters of the DVD-RW, DVD-RW DL and DVD-ROM DL media:
| General Parameters |
DVD-RW |
Dual Layer DVD-RW |
Dual Layer DVD-ROM |
| User data capacity |
4.7 GB |
8.54 GB |
| Track pitch |
0.74 μm |
| Channel bit length |
0.133μm |
0.147μm |
| Reflectivity |
18% to 30% |
5% to 10% |
18% to 30% |
| I14/I14H |
> 0.60 |
> 0.50 |
> 0.60 |
| I3/I14 |
0.15 min. |
0.20 min. |
| Jitter |
< 8.0% |
< 9.0% |
< 8.0% |
| Track path |
- |
Opposite |
Parallel and opposite |
| Reading power |
0.7mW max |
1.0mW max |
- |
| Recording speed |
Max. 6x |
2x |
- |
| Addressing method |
Woobble & LPP |
- |
The basic differences among the disc formats is the reduced reflectivity of the DVD-RW DL (5% -10%), as well as the increased reading power required to read the DVD-RW DL disc (1.0mW max).
The DVD-RW DL discs are adopting the Restricted overwrite and layer jump recording modes, already applied to DVD-R DL media. The recording order shall be from layer 0 to layer 1, and layer 1 on the recorded layer 0 is filled up with data at finalization. However, the writing strategy (laser pulse) has been modified compared to that used for DVD-R DL media.