• Blackmagic Design

  Field reversal issue

  Posted by David Braswell on January 27, 2006 at 3:28 pm

  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.

  David Braswell replied 20 years, 3 months ago 3 Members · 5 Replies
• 5 Replies

• 

  Shane Chadder

  January 27, 2006 at 3:44 pm

  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?
• 

  Shane Chadder

  January 27, 2006 at 9:01 pm

  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
• 

  Jeff Brown

  January 28, 2006 at 6:09 pm

  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
• 

  Shane Chadder

  January 28, 2006 at 7:22 pm

  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
• 

  David Braswell

  January 31, 2006 at 2:20 pm

  Thanks everyone for your help with this. Reversing fields and re-interlacing did fix the fielding issue.

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