Frame rate of video affected by composite mode.

[Don Walker]

The US frame rate used to be 30 frames a second or more specifically 60 fields a second to match the power grid frequency. It changed to 29.97 to take care of some harmonics issues in dealing with the color subcarrier of 3.58 Mhz or should I say 3.579545. If the US was to move to 25fps, we would have to have 60fps shutters on to deal with the lights strobing at 60 fps in our pictures. The world should probably agree on a common power line frequency and voltage before it begins to tackle a common TV frame rate. I think technology is allowing us to become framerate independent slowly but surely.
Don Walker

John 3:16

[Michael Gissing]

Don, shutter speeds are easy to deal with, regardless of frame rate. You will not get countries to change their power grids, but there is no reason to lock frame rates to power any more.

As for football Dave, we broadcast smooth motion Rugby here at 50i and it is just fine. Watch it on a 100hz TV and it is buttery smooth.

Douglas Trumble went for 60 fps for Showscan, but my understanding of his research is that 50fps was enough to give the smooth motion he was after, which was basically the eye’s inability to resolve the grain of a single frame. He went for sixty to be compatible with 24fps cinema convention, but 50p is all you need.

The main argument in favour of 25p or 50i or 50p is that the majority of the worlds broadcasters and population are based on 25fps. It is totally US-centric to continue with the old NTSC decimal frame rates and the inherent timecode variables. Why do you need 23.976, 24, 29.97 DF & non DF plus 30, 59.94 and 60? Yes 60 is more divisible but what is to divide? Compared to the shit fight of dividing frame rates that need to resolve to three decimal places, 25 fps is already a standard and streets ahead as far as install base goes.