Interlace Stuttering & Field Order? at DVinfo.net

Jared Gardner · March 18th, 2013, 10:45 AM

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 · March 18th, 2013, 11:02 AM

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.

March 18th, 2013, 10:45 AM	#1
Jared Gardner Regular Crew Join Date: Jun 2008 Location: Baton Rouge, LA Posts: 48	Interlace Stuttering & Field Order? 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?

March 18th, 2013, 11:02 AM	#2
Battle Vaughan Trustee Join Date: Nov 2008 Location: Miami, FL USA Posts: 1,505	Re: Interlace Stuttering & Field Order? 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.