Um, well, previewing your footage at half res eliminates/ interpolates every second line. There is no magic in that. You need to work at full res and 100% zoom. As to your original problem - you will have to cut the segments up and apply an effect like RevisonFX FieldKit to de-interlace selectively.
strange you did not post about your interpret field settings and pulldown settings. If you check, the image might be essentially interlaced by AE. upper or lower field is determined by the footage type, size, SD,HD etc.
like Mylenium said, full res needs to see the frames and not draft mode either.
QT probably deinterlaced too.
Since you said the interlacing goes away, I tend to think its not 23.976 footage with 3:2 pulldown or you'd run into a major cadence editing issue. I believe you have standard interlaced 29.97 footage.
You were right the QT is in fact interlaced, top field first. The only app that would allow me to see this is compressor. Every other app including Telestream Switch said it was progressive.
So I de-interlaced with interpret footage in AE and looks good.
So I have 2 more questions:
1. What app do you use to analyze QTs, especially if header info might be incorrect, like I suspect with this file? I was using VideoSpec which was great: VideoSpec for Mac | MacUpdate
Sadly, they are no longer updating for new OS. So I'm trying to replace it, and Telestream's Switch isn't up to the task.
2. I still don't understand why AE can play out the QT, SDI, via my blackmagic card and the interlacing issue disappears without me having to de-interlace in the interpret footage dialog. I record that output signal to a blackmagic SSD drive, import the new quicktime, and the interlacing is gone. I would have ran with this solution, if AE could have sustained real time playback.
So you and Mylenium said if the preview monitor is set to half resolution, draft, or not 100% zoom, that magically gets rid of de-interlacing issues. So setting preview monitor to half resolution somehow allows AE to de-interlace the file on play out, or is AE intelligently de-interlacing on it's own when playing out SDI? Trying to understand why play out de-interlaced the file, or added motion blur
I guess I don't get it for a couple of reasons. 1, I could see the de-interlace issue in the preview monitor at half resolution, when I simply loaded the clip. However, once I loaded the composition into the same half res preview monitor, the interlacing goes away. 2, I think the motion blur settings in the advanced tab are affecting the preview monitor. Or there is some composition setting I'm not transferring in the render queue. Although I tried a bunch.
If I load the same clip in Symphony, preview monitor also looks good, just exports that remains a problem.
Since these interlacing issues only exist on progressive scan (computer) monitors, not broadcast monitors, is the preview window for Comps in AE somehow mimicking a broadcast monitor?