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TUCoPS :: TV, Cable, Satellite :: vqual.txt

Getting better quality with VHS copying




Video Quality in Editing
February 15, 1994
Moe Rubenzahl, Videonics, 76702,466

A certain amount of quality loss is inevitable whenever videotapes are copied, as they are in editinThis note discusses some ways to maximize the quality of your copies.

- Most important: Reduce the number of "generations" (successive copies). Whenever possible, plan yoediting so that the final results are second-generation (copies of the original) rather than thirdgnration (copies of a copy). Professionals, using professional tape formats, can get away with man gneations but the loss inherent in even the finest consumer and semi-pro machines demands that weminmiz the number of generations. The picture in a third generation tape is significantly worse thn tht ofa second-generation copy.

If you are adding sound, try to do so as you edit rather than as part of an extra copying step (see  separate note AUDIO.TXT). 

If you are making copies of an edited production for other people, the copies will be third generati A way to avoid this is the use of an edit controller to do the editing. With an edit controller, uhas Videonics Thumbs Up, you mark scenes and the edit controller automatically supervises the recrdng You can repeat the automatic assembly step to make additional copies and each one is second-gnertio. This is an advantage over copying the edited production, which would give you third generaion.If yu are making many copies, consider a professional duplication house. Their equipment provies sinificntly better quality than you can do at home. 

- Important: Always use the fastest tape speed (SP). It will deliver much better results than slowereeds.

- Use the best formats available. Super-VHS and Hi8 are better than VHS and 8-mm (and pro formats aretter still).

- Use high-quality equipment. 

- Many VCRs and camcorders have extra processing circuits designed to enhance the playback of tapes.is enhancement boosts the edges and makes the picture look sharper to some viewers. But it actuall erades the overall quality and when a tape is copied, it can cause a major degradation of the finl eslt, especially when used in successive generations. There are two common controls that can tur th prcessing off. 

Look for a switch marked EDIT. Turn it ON to disable the processing circuitry that is designed for ving but tends to screw up copies. (Yes, it's confusing -- EDIT ON means the processing is disabledfrediting use.)

Look for a switch or knob marked SHARPNESS. Turn it off, or to its middle position.  

Many discriminating viewers leave the SHARPNESS control at the mid-setting and the EDIT switch on alhe time as they dislike the overemphasis that the circuitry adds when EDIT is off.

- If all your equipment has S-video (Y/C) connectors, use them  rather than composite (RCA-style) coctions. These will deliver moderately better color separation.   

- Use decent cables. Use good-quality cables for connecting your equipment. It's not necessary to ushe fancy, very expensive cables with gold-plated connectors and big advertising claims, but cheap,fisy cables can cause problems. Something in between is probably a good idea. 

- Simplify connections. Anything you add to your setup is a potential source of problems. Avoid switrs, enhancers, etc. that you don't need. Try making a copy with and without any intermediate equipetto see if it is improving or damaging your quality. 

- Use a time base corrector (TBC). A TBC will remove the jitter and wobbley action inherent in all V and camcorders. This wobble is not too evident in the first generation but successive generationsgetly increase the problem and may even cause color shifts and waving at the top of the picture (fagin). 

The TBC will not usually affect the color or noise in the picture but its correction of the time basdds quite a lot to the quality. I have seen fifth generation copies that were TBC'd at each step. hywere amazingly good (though it's still a good idea to avoid excess generations). Use the TBC at ac cpying stage as it cannot clean up all the time base error introduced at earlier copying steps.

The Videonics Digital Video Mixer includes an excellent TBC.

- Use an enhancer -- maybe. Enhancers are often oversold. They can't add detail that has been lost athey can't remove noise without affecting some of the desirable details in the picture. But the betehancers can make a visible difference. But have realistic expectations: You probably can "make adola out of 99 cents," but don't expect to make a $1.25!

- Use a video processor. Much more useful than an enhancer is a video processor which can improve thicture by correcting color, contrast, lightness, etc. Unless all your originals are perfect, a goo rcessor can improve your results. 

The Videonics Video Equalizer combines a processor with a digital enhancer and noise reduction circu plus and audio mixer.

- Watch for copy protection. Many commercial tapes have a special signal recorded in the invisible pion of the picture. This signal is meant to react with circuits in your recorder to make copies lokbd. The most common form is called Macrovision. If you attempt to copy a tape with this signal, te op will flash and jump and will be unwatchable. 

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(c) 1994 Videonics, Inc. 

Videonics manufactures a complete line of video editing equipment for the amateur and professional vographer. For information, call 800-338-EDIT or 408-866-8300. Or send e-mail to Moe Rubenzahl, Comueve id 76702,466.

Videonics products are supported in CEFORUM and CEVENDOR forums on CompuServe. GO VIDEONICS to reache Videonics section of the CEVENDOR forum. 




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