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Tamarack Video Services
Why Video
Tape Decays & Why Transfer to DVD
by Dr. Didgie, DDT (Doctor of Digital Technology)
"I'm not a real doctor... I don't even play one on TV"
Video tape, like the low cost consumer tapes such as VHS are composed of many different layers of materials.
The main layer is the tape itself, usually made these days out of Polyester, PET, Mylar or the like. This layer is prone to physical changes due to mechanical damage, temperature extremes (both hot & cold) & humidity. The tape can stretch, shrink, crinkle, bend or fold, making it very hard to correctly pass through the transport system of your player.
The second major layer is actually composed of a number of sub layers such as the magnetic media (either ferrous iron or other metallic particles) which are held on to the tape by the use of a binder (glue). These particles carry the video information on the magnetically aligned particles. Over time (5 years or so) and with repeated playings these particles can either flake off, turn to dust, get sticky, get scratched off or even de-magnetized if set to close to a strong magnetic field (an atomic blast or even your 500 watt surround sound speakers for instance) for an extended length of time.
The last major layer is the base... the underside of the tape. It doesn't carry video information but it may have lubricants impregnated in it or even have abrasives in it. It can pick up dirt, hair, dust and deposit it on your tape player's read heads, tape guides & rollers. The video tape player is the source of many tape problems. A poorly maintained VCR/Player can scratch the tape, it's dirty rollers & mis-aligned tape guides can cause any number of different tape edge problems. These problems may compound tape playback errors such as time base errors, alignment errors.
The main problem of video tape signal degradation is caused by the metal oxide either sloughing off, or oxidizing. Playing back a 20 years old VHS or Betamax tape will be less crisp now than when you viewed it a decade ago. You remember it being sharper & more colorful than what it is today. This is usually caused by metal oxide problems that I mentioned earlier. If a tape won't play without the jitters it's probably video tape edge damage or tape length distortion.
None of these problems will go away or get better with age. Many video tape manufacturers will not actively tell you how long video tapes will last but "secretly" they say that you should make a new master every five years... right! Compounding the problem is that most of our family tapes are in analog/composite form. All that really means to most of us is that IF you do make new masters (copies) from the original before it disintegrates you are "going down a generation". That means you are copying any defects the tape may now have, plus losing contrast detail, sharpness, sound quality etc each time you make a new copy... if you copy it to analog/composite format again.
You can transfer the video to a digital video tape format but it is expensive and you then need to make new copies of that every five to ten years anyway. Why not make a transfer over to DVD? DVD's do last longer than tape for sure but did you know that DVD's are also prone to oxidation just like video tapes? Although DVD's don't record the digital video signal on ferrous metal like tape does, they use a reflective surface to bounce the laser back into the read head of the DVD player. The same lack of manufacturer info here folks. Who knows how long a DVD lasts? But the current guess is about twenty years. There are ways to get more years out of the DVD. Gold! Yes gold. You can buy (we use them) gold DVD's. No they are not solid gold like NASA used. These use a very thin gold reflective surface that will not oxidize.
If you want to transfer to DVD, keep in mind that editing this DVD in the future will give you those "generation" problems that I mentioned before. Video takes a lot of space (memory) and it is usually compressed to death before it is placed on a DVD. Just like other compression formats (like JPEG, MPEG), compressed video formats don't de-compress well. They loose that snap, that sharpness, etc.
If you know that you will plan to edit the video at a later date say into a compilation of the "Smith" family history, transfer it first to a computer hard drive as an uncompressed format like AVI. It will take a huge hard drive to store it as one hour of uncompressed video (AVI) will require close to 13 gigabytes of memory.
Just keep this in mind... remember 8 track audio tapes, audio cassettes & LPs? Video formats too have & will continue to change & become outdated as well. Keeping your keepsakes updated to the new formats will insure your treasures will be healthy & viewable years from now.