May 15, 2006Video Grab-Bag While most of the buzz these days has to do with high-definition TV, Blu-ray vs. HD DVD, and other bits of leading-edge video technology, many people still hang on to their old equipment and recordings, and have questions about how to get the best out of them. Heres a small sample:
Bill says, "I have boxes full of Hi8 video of my children, and my VHS wedding videotape is 12 years old. Knowing that tape deteriorates over time, I would like to convert these analog tapes to digital and then burn the digits on to DVD as soon as possible." He wants to know the best way to do this.
First, I dont think the fragility of video (or audio) tape is as great as some would have you believe. Yes, there are some horror stories of binder (the glue that holds the oxide onto the tape itself) gumming up and rendering a tape unusable, but these tend to affect individual batches of various brands rather than all tapes of all brands. One way to protect your investment is simply to make a copy of your precious recordings on tape from another manufacturer. The chances of both becoming corrupt are slight, as long as theyre stored carefully. For instance, if you were to dub your VHS wedding tapes to Hi8, you would lose nothing in quality. Still, it means youll always have to have an analog player.
To make an interim digital copy, you could buy one of the numerous digital camcorders available and make copies on that. Or simply buy a DVD recorder and go directly to that.
David has been haunting yard sales and flea markets, and has discovered some unusual video formats. He wonders if a Video CD (VCD) is the same thing as a CD Video (CDV). He says he still has an older laserdisc player that will also play CDV discs, but he needs to know just what it will actually handle.
Its confusing, but VCD and CDV are very different. The CD Video format, concocted some years ago, is a disc containing up to five minutes of video plus digital audio, as well as up to 20 more minutes of music alone. The video portion was compatible with a laserdisc signal; in fact, the promoters of the system hoped the term CDV would be applied to all the video applications. The CDV format went nowhere, but many manuals of older LD players mention it (and if you find any CDVs, you can indeed play them on those LD players).
Video CD is an early video-disc format that was popular in Asia for movies and karaoke applications. It used an early form of MPEG video, and the picture quality is often quite poor, especially when compared to a DVD image. Such a disc wont play in an LD player, but most DVD players will play VCDs.
Finally, two terms continue to puzzle a reader named Dell: pan-and-scan and anamorphic. "I have come to appreciate that pan-and-scan denotes classic televisions 4:3 aspect ratio," he notes. "Panning with a camera means moving the field of view gradually across a scene, and scanning may mean any number of things, but what does pan-and-scan mean regarding the 4:3 aspect ratio? Anamorphic always appears to be linked to the term widescreen, so what does anamorphic mean in conjunction with the widescreen display?"
Dont take the elements of the phrase pan-and-scan too literally (its also often called full screen). Its a process by which a movie shot in a widescreen format (i.e., most of them) is adapted to fit a standard 4:3 (1.33:1) "Academy Ratio" screen, which most televisions still have. One method would be simply to use the center portion of the image and crop off the sides, but thats never satisfactory. Instead, the video engineer selects the portion of the original widescreen image with the most important picture information, and transfers that to the 4:3 version. Sometimes the relevant area changes within a single shot, in which case the engineer pans horizontally to catch what he deems the most important part of the image.
There are two ways to record a widescreen image on a 4:3 medium. One is simply to float the picture in the middle of the screen so that it fills it horizontally but leaves black bands above and below the picture. This is called a letterboxed image. The alternative is to intentionally distort the image (which is what anamorphism literally means) by squeezing it in the horizontal direction but not the vertical. That allows the entire image to fit a 4:3 screen, using all the scanning lines. If you watch such a picture on a set not equipped to decode it, everything will look unnaturally tall and skinny. Widescreen sets are equipped with circuits that stretch the picture back to its proper width. This reduces horizontal resolution to some extent, but DVDs typically have high enough resolution that that doesnt matter.
In video, this anamorphic process is the electronic equivalent of the optical systems that have been used in movie theaters for decades, the best-known being CinemaScope and Panavision.
...Ian G. Masters