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Field reversal issue
Using a Decklink SP here with 5.31 and WinXP Pro on a Blackmagic “blessed” SuperMicro MB w/2G RAM. I’ve an 8 bit Blackmagic project (D1, 720×486) where I’ve loaded Beta SP video through the component connection. On the same sequence timeline I’ve also placed DV footage ingested via firewire from a DSR-45. Any effect I apply to the DV footage and render produces a stuttery, strobed look in the rendered footage. Is this a consequence of mixing DV footage with D1 resolution footage, or am I experiencing other problems?
Incidentally, a recently applied dissolve between the Beta and DV footage showed a slight shift in position of the incoming DV footage in the dissolve.
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5 Replies
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Yes DV gets shifted (up I think) a line during rendered FX so the fields end up reversed. A workaround is reversing the fields or shifting the video down a line for the duration of the render.
I’m not sure if this is fixed in 5.4 or not. I didn’t notice the problem in a peice I am currently working on in 5.4.
Is it fixed Luke? Matt?
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I take that back. No it isn’t fixed in 5.4, not with PPro1.51 anyway. So you’ll need to reverse the fields or shift the video down a line for the duration of the FX.
Shane
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I believe this happens due to the 480 footage being centered in a 486 image, so it’s moved down 3 lines (or up 3 from the bottom). Shifting interlaced footage up or down by an odd number of lines is the equivalent of reversing fields. Move it up or down 1 more pixel/line as Shane suggests, and you have an even # shift, so no field reversal.
I go with reversing the field interpolation, as it’s easier for me to remember to do. But they should give equivalent results… in a perfect world, anyway.-jeff
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There is another work around I’ve tried breifly. When you are done capturing you can create a black magic NTSC 4×3 8bit job but go into custom settings and set the height at 480 instead of 486. Import your work into this job for editing.
I only did a little work this way so I’m not sure its perfect.
Shane
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Thanks everyone for your help with this. Reversing fields and re-interlacing did fix the fielding issue.
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