What church libraries should know about optical media
The argument about how many angels that can fit on the head of a pin aside, it is amazing the amount of information that can be stored in a compact format.
It wasn't all that long ago that we worked to fill a 3.5-inch floppy disk with 1.22 megabytes (MB) of storage, roughly 400 pages of text. Now on a single-layer, DVD's can hold 4.7 gigabytes (GB) of information, about 2 hours of video or more than 1.5 million pages of text!
Working in the media center for the church, librarians are often asked questions about this newest media form. Here are answers to some questions you may have already been asked:
What's the difference between all those formats?
DVD-R and DVD+R disks can be written onto once, while DVD-RW and DVD+RW can be rewritten up to 1,000 times.
Different manufacturers utilize - (dash) or + (plus) formats, which may lead to a recorded DVD playing fine in one player, but not necessarily in another brand. The - (dash) formats are older than the + (plus) formats and are generally more universally playable in DVD players. Sony introduced the first multiple-format DVD burner in 2003.
How long does information remain on a DVD?
The information on factory-pressed DVDs is much more stable than any of the formats above, designed to last between 50 and 300 years. The DVD+R and DVD-R formats, in turn, are dye-based and may last between 25-250 years, depending on the dyes used and the quality of the recording.
Rewritable disks are even less stable and data could last for as little as a few months, although it typically lasts longer. Therefore, do not use these for long-term information storage.
What about the high-definition (HD) formats? HD DVD or Blu-ray?
The battle between the two HD formats is over, as in recent weeks movie studios and equipment manufacturers have announced their support of the Blu-ray DVD format. A prominent USA Today article noted the end of the format war.
Is now the time to buy? Well, maybe not yet, as not very many titles are available, and player prices, which were dropping, may now stabalize for the time being. (The one exception is if you are considering a PlayStation 3, which uses the Blu-ray format.)
What factors affect a DVD's lifespan?
Some factors that can damage or interfere with DVDs are:
- Labels on disks
- Writing directly onto a disk (except with a Sharpie-type marker)
- Using paper labels rather than those designed for DVDs
- Storing disks on their end
- Humidity and sunlight
- Scratches, fingerprints, smudges and handling disks with hand lotions