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December 25, 2005
Video confusion & conversion
Looking into the PlayStation problem further, you may go far afield enough to get to the VideoInterchange.com site where PAL, SECAM, NTSC conversion is explained:
Converting between different numbers of lines and different frequencies of fields/frames in video pictures is not an easy task. Perhaps the most technical challenging conversion to make is the PAL to NTSC. Consider that PAL is 625 lines at 50 fields/sec as opposed to NTSC's that is 525 lines at 60 fields/sec. Aside from the line count being different, it's easy to see that generating 60 fields every second from a format that has only 50 fields might pose some interesting problems. Every second, an additional 10 fields must be generated seemingly from nothing.
Of course there is no reason related to persistence of human vision for PAL to be different from NTSC, for example. 25 or 29.97 fps is already faster than the rate used at the movies.
Engineers in the US worked on NTSC around 1940. They joked that NTSC stood for "Never The Same Color" due to the color subcarrier frequency ending up unstable by design.
Walter Bruch of Telefunken Germany designed PAL, which did not have the same problem. Some folks seem to be able to see flicker since PAL only refreshes 25 times per second, instead of almost 30, but the brain compensates quickly. So I was wrong about the marketing. It's just that Bruch didn't come up with PAL until 1967, at which point the US had probably already built things out based on NTSC.
Later there was also SECAM:
SECAM was not developed for any technical reason of merit (as was PAL) but was mainly invoked as a political statement, as well as to protect the French manufacturers from stiff foreign competition. In that regard, they were highly successful!
(The source for the quotes is the VideoInterchange.com article mentioned above.) How soon will we get out of this mess of old hardware?
Posted by Mark at December 25, 2005 11:57 AM
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