|
|
SEAPAVAA Newsletter |
|
SPECIAL FEATURE: Archival vs. acquisition/distribution/viewing "Archival requirements not the same as for acquisition/distribution/viewing"By Jim Wheeler
We are in a digital revolution and archivists are being told to jump on the digital train. Most technical people are advising archivists to transfer their video material to one of the small digital videotape formats, such as DV or DVC-PRO. These formats make nice looking pictures, the cassettes are small, and the cost of the equipment is reasonable. Or, why not DVD? Anyone who has viewed a movie on DVD has to be impressed with the picture quality. All of the post-production houses have gone digital, so everything that we see on television today have been digitized in some way. So, if everyone else is switching to digital, why shouldn't archivists? The simple answer is that archivists have a different agenda than consumers and the people in the broadcast television business. Archivists must select a medium that has the best chance of surviving for many years, and archivists must select a system that will not alter the recorded material. There is nothing wrong with digital, per se. Whether or not a particular digital videotape format is adequate as an archival medium depends on the durability of the tape being used and how the audio/video signals are processed. The main problem with the low-cost digital formats is that they are heavily compressed. That is okay with most people but a no-no for archivists. Also, all of the low-cost formats sample the incoming signal at a low rate and that means that much of the detail is lost. A good sample rate is 10 bit at 4:2:2 and none of the low-cost formats can handle that rate. Additional issues are those of thin tape and the robustness of the cassette. There are several possible problems with DVD as a video archival medium. One is that DVDs use heavy compression, and compression discards some of the finer details of the original. The second problem is that archivists will use recordable DVD and there have been no tests that prove that a disc recorded on a machine made by one manufacturer will play on machine made by other manufacturers. There is also the potential problem for DVDs to delaminate. Some DVDs have an adhesive to hold the two halves together and adhesives have a bad habit of coming unglued after a few years. The main problem with the high-quality digital videotape formats used by the post-production houses is that the equipment is very expensive. The cheapest is D3 and a D3 tape machine costs around US$30,000. D5 is a great format but a D5 machine costs US$60,000
|