[Myrddin]

By the way, I never understood why color televisions use a frame rate of 29.970Hz. I know it's 3,579,545Hz/227.5/525, but why not use a colorburst of 3,583,125Hz? Or if that would be bad, 3,567,375 (using 226.5 chroma clocks per line)? What's magical about 3,579,545Hz?

The answer lies in the 60 Hz AC line. The 30 frames per second / 60 fields per second was selected to avoid having a heterodyne beat causing a moving dark band across the screen. The chroma subcarrier value was constrained to work with the frame rate/line rate.

[supercat]

The answer lies in the 60 Hz AC line. The 30 frames per second / 60 fields per second was selected to avoid having a heterodyne beat causing a moving dark band across the screen. The chroma subcarrier value was constrained to work with the frame rate/line rate.

Black and white video was broadcast at 60.00fps to prevent beating against the AC line frequency (hooking old television sets up to some computers or video games works poorly because many computers have a frame rate that's off by about 0.1Hz). So why choose a chroma rate that causes the field/frame rate not to be 60.00/30.00Hz?