There are many different types of writable and rewritable DVD media on the market today. These formats include:
There are also "General Purpose" and "Authoring" discs. DO NOT confuse the "Authoring" media with the term for content development (making / editing what eventually goes on the DVD). The most common type of DVDR is the General Purpose type - if you do not know that you have an actual authoring recorder drive then you most likely have the general purpose type.
DVD-RAM is primarily used as a data solution, although the type of data stored can include many types of data including video. Early version 1 recorders used 2.6GB discs (or double-sided 5.2GB discs), but current version 2 drives can handle 4.7GB discs (or double-sided 9.4GB discs). These discs are traditionally housed within a cartridge which cannot be opened, so that the media is well-protected. Newer Type 2 cartridges can be opened however, which is important for some people who wish to read these discs in drives or standalone DVD-Video players/recorders which do not use the DVD-RAM cartridge loading mechanism.
DVD-RAM is a sanctioned format of the DVD Forum, a consortium of companies involved in the development of DVD standards. DVD-RAM is a very robust data storage solution, theoretically allowing greater than 100,000 rewrites per disc. Similar to a hard drive, a DVD-RAM disc allows full random read/write access with defect management. An additional benefit of DVD-RAM is that it is a tried and true technology which has native support in Windows XP and Mac OS X. The discs are usually formatted with the UDF format, but can be formatted to such formats as FAT32 in Windows and HFS+ for Mac, or others. The main drawback of DVD-RAM is its very limited read compatibility in DVD-ROM drives and standalone DVD-Video players. DVD-RAM read support in these machines is increasing however.
DVD-R and DVD-RW
DVD-R and DVD-RW are both also supported formats of the DVD Forum. Both formats use 4.7GB discs, although some DVD-R drives used 3.9 GB discs.
DVD-R is a write-once recordable format which allows excellent compatibility with both standalone DVD-video players and DVD-ROM drives. There are two main types of 4.7GB DVD-R discs: DVD-R for General Use and DVD-R for Authoring. Most consumer drives use the former cheaper General Use discs, while many higher end professional drives use Authoring discs. The correct media type appropriate for the drive must be used when burning. However, once burned, the discs should be able to be read in either drive type. (General Use DVD-Rs are designed to prevent backup of encrypted commercial DVDs).
DVD-RW uses rewritable discs which are rated at more than 1000 rewrites in ideal situations. Unfortunately, DVD-RW does not enjoy the same excellent compatibility with DVD-ROM drives and standalone DVD-Video players that DVD-R enjoys. Another drawback is that unlike DVD-RAM, one must generally erase a DVD-RW disc before reuse.
Most DVD-RW drives should also be able to record to DVD-R. However, the reverse is not true. Many older and some current DVD-R drives are not capable of writing to DVD-RW discs (but may be able to read burned DVD-RW discs). Some drives can also record to CD-R and CD-RW.
Currently DVD-RW and DVD-R have heavy penetration into the multimedia market as well as the general consumer market. For instance the Apple SuperDrive, found in higher end Mac computers used in multimedia creation, is simply a DVD-R/DVD-RW (and CD-R/CD-RW) capable drive.
DVD+R and DVD+RW
These two formats are backed by the DVD+RW Alliance. While these formats are not sanctioned by the DVD Forum, several members of the DVD+RW Alliance are also members of the DVD Forum.
DVD+RW, like DVD-RW, is a rewritable 4.7GB DVD format. DVD+RW, however, in some ways offers some technical advantages, which for example include: lossless linking (which in turn more readily allows editing of a disc's contents after an initial write while maintaining integrity of the remaining data), currently slightly faster recording speeds, and optional future Mount Rainier drag-and-drop file access support (also known as DVD+MRW). However, DVD+RW does not have the very high compatibility with standalone DVD-video players and DVD-ROM drives that the DVD-R format enjoys. The level of compatibility of DVD+RW is said to be similar to that of DVD-RW. Also, DVD+RW does not currently have the same level of market penetration as DVD-R.
DVD+R is a format that only was introduced to the public very recently (early 2002). DVD+R is a write-once 4.7GB format which promises to dramatically increase the compatibility with standalone DVD-Video players and DVD-ROM drives. Whether that claim is fulfilled remains to be seen, but initial reports have been very positive. It must be noted, however, that 1st generation DVD+RW drives do not support DVD+R burning, and it is likely that most cannot be upgraded to do so either. If one wishes to have DVD+R burning functionality, one must purchase a newer drive specifically designed to do so. DVD+R discs currently are somewhat more expensive than DVD-R discs, but prices will likely drop with time. Burners that write to these discs is the HPDVD100i and the DVD-Writer DVD200i drive
So what should I buy then?
The choice largely depends on one's usage environment and usage preferences. DVD-RAM offers very good support for data applications and is used in many professional environments, but the discs cannot be used in most DVD-Video players and DVD-ROM drives, making it less attractive for the average home user. A few newer DVD-Video players and recorders do support DVD-RAM however.
DVD-RW/DVD-R has the highest market penetration and DVD-R offers the best proven support for video playback in standalone DVD-Video players. Not only is it very well supported for PC users, it is the format of choice for the Mac.
DVD+RW/DVD+R is beginning to gain market share, and the data capabilities of DVD+RW do offer some advantage to DVD-RW. DVD+R compatibility with DVD-Video players is as yet (April 2002) not proven to be as high as DVD-R, but initial reports have been very favorable and suggest a significantly higher level of compatibility when compared to DVD+RW and DVD-RW.
What about external DVD recordable drives?
These drives exist in SCSI and IDE formats. Most external DVD recordable drives use essentially IDE drives with USB 2.0 or Firewire 1394a bridges and custom housing. These drives can be purchased as complete drives, or one may purchase standard 5.25" bay DVD recordable drives for use in a 3rd party USB 2.0 or Firewire enclosure. Let us know if you need an external burner, any of our DVD burners can be inserted into an external case for use with USB or Firewire interfaces.
Thanks to www.AnandTech.com for this helpful information