I was watching a live boxing fight from 1962, How did they add graphics or text to the screen on sports events, news, etc?
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The earliest, simplest BW television titling was done by simply adding a synchronized camera output to the signal before broadcast. The camera would be pointed at a black board with white lettering. Since “black” is 0 volts you just see the fight and white is 1 volt adding it to the fight is more than 1 volt but gets clipped to 1 volt, which is “white”.
The complex part was having the camera’s output synchronized to the cameras recording the event. NTSC signal has timing and calibration pulses mixed with the actual image. Getting all of the cameras’ to generate the pulses at exactly the same time is required to stop the picture “glitching” when switching cameras, and to have the title text show up where you want it to over the image.
This synchronization is done by Phase Lock Loop, a topic for another ELI5.
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