@stylus @codinginquarantine
And when colour was first added to the NTSC standard, which already had 2 signals for picture and sound, it had to be done without making black and white TVs obsolete overnight. That was solved by changing the frame rate from 30.00 to 29.97 (which persists to this day).
https://glydeck.blogspot.com/2011/07/why-do-we-have-2997-frame-rates-and-not.html?m=1