As I spent a dozen years overseas, I knew a little about multisystem televisions and the difference between PAL and NTSC standards. I may have even known that European PAL is broadcast at 25 frames per second. There were all sorts of things I didn't know, however. For example, standard North American theatre films are shot at 24 frames per second. Therefore after conversion, films run a full 4.2% shorter when converted for a PAL broadcast. There is even a noticeable difference in pitch.Conversion to NTSC's 29.97 frame rate requires even more elaborate changes. First, the film is slowed down by 0.1%. Then, four frames need to be stretched onto five. Yet, because of NTSC's interlacing, four frames actually have to fit across ten. So the first film frame is saved on two NTSC frames, and the second is saved on three, and the third saved on 2, and the last saved on three. This continues. The process works but it introduces something called Telecine judder which is why movement on home TV equipment was never as smooth as in the theatre.
These examples stem from historical factors. Some go back all the way to the choice of using 50Hz phase electrical current in Europe and 60Hz in North America. It is amazing how we are often impacted by previous decisions. We seldom start from scratch although that would probably be far more efficient. If we didn't have to contend with legacy technology, we could create much better and more universal modern systems, from a computer OS to a television's technical standards.
