Signal Degradation in Multiple VCR Loops


On the Loop

I have a cheap distribution amp that goes from one to three outputs. I currently have each VCR looped to one more VCR for a total of six. Someone told me there is not much signal degradation if you loop only once. But if you loop to additional VCRs, you would start to see a loss in quality. Is this right?

Josh Hunt

Las Cruces, NM



Your friend is right. Every time you make an analog copy you will add noise to your signal. And each time you loop the signal through another device (VCR, titler, etc.) you open the door to even more noise. The question is not if loss will happen, but how much loss you will actually see. The one element that will affect your final duped videos more than anything else is the quality of your master tape. Start out with the highest quality video possible. That said, there are a number of others factors that will directly affect the quality of your dubs.

Each component in your dubbing chain has unique characteristics that could affect the final output. The first step to a clean signal path is using the best type of cable that you can. For instance, DV carries a higher quality signal than S-video, S-video is better than composite and composite is better than RF. Another often-overlooked factor is the quality of your cables. Regardless of the type of cable you use, we suggest using the thickest and shortest cable possible.

When all is said and done, the best way to tell whether there is significant degradation in your dubs is to compare your copies to your master tape. Whats important is that your recordings look good to your viewers. So test it out and see for yourself. If there is noticeable generation loss, try to isolate the problem by looking at the factors we mentioned.



A Rose by any Other Name

In June of 1998 I upgraded my camcorder to a Canon Optura, which has a FireWire port. I did this anticipating the future when I would upgrade my computer to one that would also have a FireWire connection so I could use a nonlinear method to edit my video. The time came to upgrade and I saw a Sony VAIO digital computer that had an i.LINK connection, which I bought. Much to my chagrin, I discovered that i.LINK was not compatible with FireWire or IEEE 1394. I dont recall ever seeing anything in your magazine or any other one that mentions this frustrating incompatibility.

In fact, I got the impression from reading that FireWire and i.LINK were the same creatures and were interchangeable. When I called both Canon and Sony, they knew immediately what the problem was and told me. If you buy a Sony digital computer you must have a Sony camera. Please warn your readers. It was an expensive lesson, but more so, discouraging.

Edward Swanson

Internet



Your initial assumptions were correct, FireWire, i.LINK and IEEE 1394 all mean the same thing and youll often see the terms used interchangeably in these pages. IEEE 1394 is the name of the original standard for a high performance serial bus. IEEE is an acronym for The Institute of Electrical and Electronic Engineers, a group that wrote the standard. 1394 refers to the 1394th standard that they devised.

When the technology was first developed, Apple took the standard and branded it FireWire and successfully marketed it. Other manufacturers who used the IEEE 1394 port on their devices could use the FireWire name as long as they paid Apple a small fee. More recently, presumably in an effort to avoid that payment, Sony devised and successfully marketed their own trademark for the IEEE 1394 standard – i.LINK. But heres where the confusion starts.

When Sony initially developed i.LINK, their standard was not exactly the same as IEEE 1394 (or FireWire). This caused a lot of incompatibility issues. In an effort to remedy this, in the Fall of 1998, Sony changed the i.LINK specifications to be identical to the FireWire and IEEE 1394 standard. So now when you see the terms IEEE 1394, FireWire or i.LINK, they all refer to the same standard.

The Sony tech guys went on to explain that any camcorder or VAIO manufactured after September 1998 should be fully compatible with one another. It is because your Optura was manufactured before September 1998, that it is not compatible with your VAIO.




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