Re: Can we finally settle this?
"A friend once told me that the most powerful computer in the world was actually in a satellite and performed standards conversion of US to UK TV, which are different frame rates, different line counts and different encodings etc."
You might like to look at this: https://en.wikipedia.org/wiki/Titan_(supercomputer). No matter when your friend said it, the "most powerful computer in the world" fills entire rooms and draws from a couple of hundred kilowatts (Cray-2) to the ~8MW of the Titan. There's no way that such a thing could sensibly reside in a satellite.
Furthermore, why put the computer in the satellite when you can do the standards conversion on the ground, either before uplink (America) or after downlink (Europe)?
Even more, the hard part of standards conversion is in spatial correction. It is dead easy to convert 30fps NTSC to 25fps PAL; simply remap to the higher resolution by doubling every 6th screen line and correct frame rate by completely discarding every sixth frame. This leads to serious motion jitter on panning shots, but it is good enough that even a €15 DVD player can playback NTSC discs on PAL equipment. Proper conversion takes a lot more grunt, but wouldn't need something like a supercomputer.