Interlace Stuttering & Field Order?

[Jared Gardner]

I've seen an example of interlace stuttering where the fields have been reversed as in Fields and Interlacing - Lesson at 3:12 or so. I've tried replicating this problem by reversing the fields. I haven't been able to successfully replicate that particular effect with After Effects. Why is that?

Another thing is that I thought that interlacing wouldn't cause a stuttering effect in the first place. I was under the impression that the upper and lower fields both are taken from the same frame, with no movement between those two fields. How can you get a stuttering effect at all considering regardless of field order two fields of the same frame will be displayed?

[Battle Vaughan]

True interlacing -- as in ntsc video- is how the picture "moves." First all the odd lines are scanned, then a fraction of a second later, a new, slightly different and later image is scanned into the even lines, and so on. If they were taken from the same frame there would be no motion.

If you interlace a progressive video, perhaps what you describe would be the result.

I have encountered stuttering when the field order was reversed --- say, something shot in hdv interlaced, which is even field first, translated into ntsc, with odd field first, the later motion was being placed before the earlier motion, which produces a shimmering effect. Not lovely to look at.