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FAQ on DVDs

A general understanding of DVDs and what they are about.

Questions:

What does the term DVD stand for?
There are various types of DVD's can you explain a bit about those?
Err ...oookaayy ...so what speeds can I burn at?
Pros & Cons of the different DVD formats:
Err... I'm still so confused, what more can you tell me?

Answers:

What does the term DVD stand for?

DVD stands for Digital Versatile/Video Disc; a type of compact disc that holds far more information than the CD-ROMs that are used for storing music files. A DVD can hold a minimum of 4.7 GB, enough for a full-length movie. MPEG-2 is used to compress video data for storage on a DVD. DVD drives are backward-compatible and can play CD-ROMs.

DVD Video (Digital Versatile Disc Video)
For viewing movies and other visual entertainment. The total capacity is 17 gigabytes if two layers on both sides of the disk are utilized. This is the format used by Hollywood.

There are various types of DVD's can you explain a bit about those?

DVD-ROM (Digital Versatile Disc - Read Only Memory)
DVD-ROMs can currently be made in four physical formats named DVD-5, DVD-9, DVD-10 and DVD-18. DVD-5 has a 4.7GB storage capacity (versus the 650MB standard for a CD-ROM) and stores the data on one side of the disc in a single layer. This data can be in the form of software, video (DVD-Video) or audio (DVD-Audio). The DVD-9 format stores data in dual layers on a single side of the disc while the DVD-10 and DVD-18 formats use both sides of the disc to store data in single and dual layers respectively. DVD-ROM discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives. These discs cannot be written to by the user.

DVD-R (Digital Versatile Disc - Recordable)
A disc that is equivalent to the DVD-ROM but it can also be recorded to. You can record on 4.7GB single-sided and 9.4GB double-sided DVD-R discs. DVD-R discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives. These discs can only be written to once by the user. There are two types of DVD-R drives and media. DVD-R for Authoring is appropriate for someone who wants to create a disc that can be used as a master at a duplication house. This is called the Cutting Master Format (aka CMF). It supports setting region codes and using copy protection. DVD-R for General is appropriate for someone who only wants to create a few copies of a disc and doesn't need to send the disc to a duplication house or set region codes. The correct media must be used with the appropriate drive (i.e. DVD-R for Authoring discs with a DVD-R for Authoring compatible drive).

DVD-RAM (Digital Versatile Disc - Random Access Memory)
Differs from the DVD-R in that it is re-writable many times. Discs are available in capacities of 2.6GB or 4.7GB for single sided discs and 5.2GB or 9.4GB for double sided discs. DVD-RAM discs can only be accessed in a DVD-RAM drive. They cannot be used in set top DVD players or computers equipped with DVD-ROM drives.

DVD-RW (Digital Versatile Disc - Re-recordable)
A version of the write-once DVD-R format that can be written to up to 1,000 times. DVD-RW discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives.

DVD+R (Digital Versatile Disc + Recordable)
A specification put forward by the DVD+RW Alliance to complement the DVD+RW format. DVD+R discs can be recorded in 4.7GB capacities. These discs can only be written to once by the user. DVD+R discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives.

DVD+RW (Digital Versatile Disc + Rewritable)
A different version of a re-writable DVD-R format that is designed to be more suitable for both real-time video recording and random data recording. DVD+RW discs can be recorded in 4.7GB capacities. DVD+RW discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives.

DVD+R DL (Digital Versatile Disc + Recordable and Dual-Layer)
Pioneer and several other DVD burner vendors announced planned support for this new technology. This will allow you to double the amount of content you can put on a single DVD from 4.7GB to 9.4GB. You do not have to "flip" the DVD to record on the second layer, and they will be able to be played on your home theatre DVD player. New laser technologies will allow the burner to write through the top layer onto the second layer below.

Blu-Ray DVD
Blu-Ray DVD's will use blue-violet colored laser beams that are much narrower then the red lasers used for reading & writing DVD's today. As a result they are able to store 27GB of data on a single sided disk. That's almost 5 times the current 4.7GB DVD capacity. That's the good news. The bad news is that these Blu-Ray recorders are going to cost several thousand dollars and the disks they produce may not be compatible with existing DVD players. So we'll have to buy new Blu-Ray DVD players to benefit from this technology. I think that Blu-Ray will initially be used by the broadcast/ commercial television industry for storing HDTV content and programming. Once again, like everything else with DVD, we've got competing formats involved. Blu-Ray consumer products may not arrive until 2006.

Err ...oookaayy ...so what speeds can I burn at?

In most cases the burning speed can be determined from the following chart:

DVD-+R/W write speeds (4.37 GB)
1x = around 60 minutes (1x read speed is 1.32MB/s(1 385 000 000 bytes/s) = ~57 minutes)
2x = around 30 minutes (2x read speed is 2.62MB/s = ~28 minutes)
2.4x = around 25 minutes (2.4x read speed is 3.17MB/s = ~24 minutes)
4x = around 15 minutes (4x read speed is 5.28MB/s = ~14 minutes)
6x = around 12 minutes (6x read speed is 7.93MB/s = ~9 minutes)
8x = around 10 minutes (8x read speed is 10.57MB/s = ~7 minutes)
12x = around 7 minutes (12x read speed is 15.85MB/s = ~5 minutes)
16x = around 5 minutes (16x read speed is 21.13MB/s = ~3.5 minutes)

DVD-+R DL write speeds (7.95 GB)
1x = around 104 minutes (1x read speed is 1.32MB/s = ~103 minutes)
2.4x = around 44 minutes (2.4x read speed is 3.17MB/s = ~43 minutes)
4x = around 28 minutes (4x read speed is 5.28MB/s = ~26 minutes)

This is by and largley, estimated times, depending on RAM, CPU speed and brand of DVD writers.

Pros & Cons of the different DVD formats:

Format	Pros	Cons
DVD-ROM	4.7GB storage capacity can be accessed in set top DVD players and computers	cannot be written to by the user
DVD-R	can record on 4.7GB and 9.4GB DVD-R discs can be accessed in set top DVD players and computers	can only be written to once by the user
DVD-RAM	is re-writable many times available in capacities up to 9.4GB	DVD-RW discs may not play back on some older or entry-level DVD systems
DVD-RW	can be written to up to 1,000 times can be accessed in set top DVD players and computers	DVD-RW discs may not play back on some older or entry-level DVD systems
DVD+R	can record on 4.7GB DVD+R discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives
DVD+RW	can record on 4.7GB DVD+RW discs can be accessed in set top DVD players and computers equipped with DVD-ROM drives	DVD+RW discs may not play back on some older or entry-level DVD systems
Blu-RAY	can record on 23.7GB discs 50GB on dual-layer	incompatible with current systems, very expensive hardware

Err... I'm still so confused, what more can you tell me?
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