Specifically, PAL-style color subsampling which is more or less YUV 422. They could have fixed it other ways, but they decided to incorporate a quartz glass pri

Specifically, PAL-style color subsampling which is more or less YUV 422. They could have fixed it other ways, but they decided to incorporate a quartz glass prism and piezo transducers to realize a 1-scanline physical delay, which they then used to do the analog variant of XORing each line with the one before.