DVD+RW - Technical Details

Technical Details

The recording layer in DVD+RW and DVD-RW discs is a phase change metal alloy (often GeSbTe) whose crystalline phase and amorphous phase have different reflectivity. The states can be switched depending on the power of the writing laser, so data can be written, read, erased and re-written. DVD-R and DVD+R discs use an organic dye.

The capacity of a single-layer disc is approximated as 4.7 × 109 bytes. In actuality, the disc is laid out with 2295104 sectors of 2048 bytes each which comes to 4,700,372,992 bytes, 4,590,208 kibibytes (KiB, binary kilobytes), 4482.625 mebibytes (MiB, binary megabytes), or 4.377563476 gibibytes (GiB, binary gigabytes).

The DVD+RW format is divergent from the DVD-RW format. Hybrid drives that can handle both, often labeled 'DVD±RW', are very popular since there is not a single standard for recordable DVDs. There are a number of significant technical differences between the 'dash' and the 'plus' format, although most users would not notice the difference. One example is that the DVD+RW style Address In Pregroove (ADIP) system of tracking and speed control is less susceptible to interference and error, which makes the ADIP system more accurate at higher speeds than the Land Pre Pit (LPP) system used by DVD-RW. In addition, DVD+R(W) has a more robust error management system than DVD-R(W), allowing for more accurate burning to media, independent of the quality of the media. The practical upshot is that a DVD+RW writer is able to locate data on the disc to byte accuracy whereas DVD-RW is incapable of such precision.