Al Limberg wrote:
Analog TV has limited fine-line resolution, but very high edge-positioning resolution in the horizontal. So, it is not susceptible to the jaggies that really offend the human visual system. The redundancy in slow moving analog TV signals allows noise to average out over a few frames, so the redundancy is sometimes useful and not really wasted. Video compression takes away this safety net, so other ways to reduce the effects of noise must be employed.
On the redundancy, while MPEG compression deliberately takes that away to save on bandwidth, Reed-Solomon and Viterbi/turbo codes actually restore it. So it's a mixed bag in digital.
But I think the good news is that the when errors are corrected in digital, they are usually completely imperceptible. Whereas in analog, they are often or usually merely tolerable.
I suppose one should expect that whatever techniques are used to control error rates, as long as these techniques are different, each will have its specific advantages and disadvantages compared with the others.
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