Fielded footage?

Probably a stupid question, but I’m struggling with tracking a piece of interlaced footage. Here’s my workflow to see if I’m doing something wrong…

  • interlaced AVI imported into After Effects (haven’t separated fields)
  • rendered out to targa sequence (rendered no fields - presumably not touching the fields at all and leaving them intact?)
  • import TAGs into Mocha and interpret as PAL uff interlaced.
  • drawn spline and set to track fields
  • exported track to AE and pasted into position KFs of logo I want to track onto footage
  • rendered footage and logo together as AVI

Does that sound about right?

Problems I have are…

  • In Mocha when I step through my footage it jerks forwards then back every other frame - indicitive of wrongly interpreted footage right? But I know FOR SURE it is UFF.
  • When I render out my comp in AE the logo has really nasty interlace movement, no matter whether I render no fields leaving footage uninterp’d, or whether I interp the footage and then render uff.

Any thoughts?

Should you always separate fields in Mocha for interlaced footage and should you always track fields?

Thanks for any advice!