How It Is Done?
First of all: no miracles.
In order to convert one video standard into another we will change three major parameters:
1. Number of Frames Per Second
For example, 25 flickers per second in PAL must be recalculated into 29.97 flickers per second for NTSC or vice versa.
2. Number of Lines
Another example, 625 lines in SECAM must be recalculated into 525 lines for NTSC. We make TV lines look thinner for NTSC, or thicker for PAL and SECAM. You can actually see these lines if you come really close to TV screen (don't stay there for a long time though).
3. Color Encoding
This is one more thing that has to be done. There is the same number of frames per second and TV lines for both PAL and SECAM. Still color encoding is different. If you want to watch a video in color, it is a good idea to take care of the color encoding as well.
Digital Video Standard Converter and TBC
We are not working hard to recalculate your video into new standard with calculator. We are using 21st century equipment instead.
Your tape is being played back in the VCR. The signal is being sent to Digital Video Standard Converter and Time Base Corrector. This very smart device makes all the necessary calculations on the fly. After that converted and corrected video signal is digitized into computer, and the new DVD is produced.
What is Time Base Correction, or TBC?
You might have noticed that when you play back recorded TV show, it usually looks not as good as if you were watching it at a show time. It's getting even worse when you try to make a VCR-to-VCR copy. This phenomenon is usually called generation loss and is considered to be inevitable for analog VCR's.
One of the reasons why it's happening is that the very complex video signal is being "trashed" every time you record it and play it back. And when you are trying to make one more copy, existing errors are multiplied by new ones. As a result your video does not look pretty.
You can compare the video signal to the symphony orchestra that performs under command of the director. Every fraction of a second (microsecond, to be precise) there is a certain chunk of information that has to be played back. But for so many technical reasons it may be a little bit too soon or a little bit too late for the very single chunk of the signal to "play its part", as if the director of the orchestra has stepped out and left his orchestra unsupervised. The music is a bit off, and it's getting even more "off" the longer the director is absent.
Time Base Corrector, often called TBC by its friends, is that director for the video signal. It steps in and makes every instrument in the orchestra play its part at precisely right moment in time, not microsecond sooner or later. In other words, TBC standardizes video signal, correcting the errors. So if you send the signal to the Time Base Corrector before recording it, you make it look better, cleaner, smoother and free from errors, thus avoiding effect of the multiplying the errors.
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