Poor compatibility is the biggest defect of DVD-RAM. Ordinary DVD drives and DVD players cannot read DVD-RAM discs. To read a DVD-RAM disc, you must use a DVD-RAM drive.
(2) DVD-R/RW standard was put forward by Pioneer Company in 1998. The recording principle of DVD-R/RW is similar to that of ordinary CD-R/RW, and the recording method of fixed linear speed CLV is adopted. Among them, DVD-R can only write data once, while DVD-RW adopts phase change reading and writing technology, which can erase and write data repeatedly. There are two sub-specifications of DVD-R for different purposes: one is authorized DVD-R, which is suitable for commercial use, and the other is general DVD-R, which is suitable for ordinary users. The main difference between the two is that the laser wavelength is different when writing and reading, and the ability to prevent copying is different. Ordinary users should pay attention to buying discs marked "for data use" or "for general use" when buying DVD-R discs.
Because the reflectivity of DVD-R disk is similar to that of DVD-ROM, DVD drives and DVD players on most computers can read it, and DVD-R has more advantages in compatibility (DVD-RW is a little worse, and some old DVD players can't read it). Moreover, among all the DVD burning discs, the price of DVD-R disc is the cheapest (the price of ordinary DVD-R disc is about 15 yuan). In the early days, the speed of DVD-R was only twice that of DVD-RW, and the speed of DVD-RW was only 1 times (it takes about 1 hour to burn an optical disc), but now there have been models with four times the speed.
(3) The specification of DVD+R/RW is mainly 7c (Philips/Sony/Yamaha/Mitsubishi Chemical-Word for Word/Ricoh/Hewlett-Packard/Thomson), which is not the official specification of DVD-Forum. Like DVD-R, DVD+R belongs to write-once data. And DVD+RW, like DVD-RW, has the characteristics of repeated writable. DVD+R/RW uses C*** burning mode, and DVD+RW also uses a data structure similar to hard disk, so the data reading and writing performance is better than DVD-RW. Although DVD+ RW also needs to be formatted (it takes about an hour), it can be formatted in the background from the middle, so you can start burning data in one minute. This is the fastest DVD burner. At the same time, DVD+R/RW standard is the only DVD recording standard supported by Microsoft. It is worth mentioning that the DVD+RW alliance has joined the "Lost Link? Lossless connection "technology. In the lossless link state, the gap between different data blocks can be as low as 1 micron, so that the read-write head can continue writing data where it stopped last time. Therefore, this format has high space utilization and data can be written randomly, which is very suitable for the application of processing video images.
However, the two specifications of DVD-R/RW and DVD+R/RW are incompatible, which causes users to be puzzled about the design and compatibility of DVD-related software and hardware. So manufacturers including Sony and NEC. Aiming at the incompatibility between DVD-R/RW and DVD+R/RW, a new specification of DVD Dual is proposed, which is called DVD R/RW at present. The DVD-RW burner can be compatible with both DVD-R/RW and DVD+R/RW, so users don't have to worry about the matching of DVD-burned discs. However, this DVD recorder also has a small disadvantage, which requires two royalties and the production cost will increase a little, so the market price will naturally not be very cheap. At present, Sony's new generation DVD recorders all support DVD dual specifications.