RE:Vision’s FieldsKit ReInterlacer

In Summary:

Purpose of FieldsKit ReInterlacer:

  • Transforms progressive video (e.g. HDp25 frames/sec) into spatio-temporal interlaced video (e.g. SDi50 fields/sec).  It achieves this by estimating the fields that would have been shot (had the original video itself been shot as interlaced) between each frame of the progressive video, via a process of motion estimation.
    •  Most NLEs do not use this “perfectionist” method, instead they at best simply combine (ghost-blur) successive frames, with no compensation for time/motion.
    • On an interlaced display, such as an old analog TV or projector,
      • The “NLE-simple” approach may lead to dynamic (changing e.g. moving) scenes and objects appearing flickery.
      • The “perfectionist” approach will instead typically avoid such flicker.

Configuration of  FieldsKit ReInterlacer:

  • Field Order: [Lower First]
  • Output Type: [= Create motion estimated fields]
    • This is not the default (oddly).  But it is the only proper way to get the expected “perfectionist” reinterlacing to happen!
  • Source Layer: [Video 1]

Supplier’s website:

Greater Perspective, Workflow & Detail:

In Adobe Premiere (CC 7.2.1), I have a 25 fps progressive-frame project at Standard Definition (SD) in PAL-Wide format.

  • It’s in progressive-frame because the source footage was shot in progressive – at 25 fps in HD 1080 (which I call “1080p25”).
    • Keeping it progressive (like the source) presumably lightens the load on the CPU/GPU.  Also, rushes and drafts tend to be viewed in progressive (H264).

Having finalised (-ish) the edit, I want to export/render to MPEG2 suitable for building a DVD – at SD Pal-Wide 50 fields per second (which I call 576i50).

What’s the best way to export from p25 to i50?

  • I asked on an Adobe forum but didn’t get the kind of answer I was looking for – basically I was advised to stick to progressive or even HD.
    • Modern flat screens can cope with progressive – but my job-customers at that time specifically required a standard “heritage” DVD, compatible with old TVs etc.
  • The “cheap & easy” (un-thinking) way would be to simply “let Premiere do whatever it does” when exporting from p25 to i50, with maximum render quality selected.
  • However, the proper way is to have motion estimation to infer the “tween” fields, namely those temporally between each frame.
    • The FieldsKit ReInterlace effect does this.
  • From web-search, I found a Grass Valley forum post recommending FieldsKit ReInterlacer.
  • Re-Interlacing can also be achieved via plugins for AviSynth (e.g. search this blog for “avisynth”), the free script-driven video-processor.  However, it’s just easier if everything can be achieved within the Adobe CC environment (at least, in principle).

My (Full-Workflow) Usage of FieldsKit ReInterlacer:

  • From the (SDp25) edit-Sequence, Export to an intermediate file – in a visually-lossless encoding format.
    • Cineform AVI.
  • Add that intermediate file to the project – in an Intermediates bin.
    • Double-check that it is being interpreted correctly – given that AVI files do not specify progressive/interlaced.
  • Drag the intermediate to the [New] button, to generate a matching new Sequence, containing the intermediate as a clip.
  • Alter that Sequence to be interlaced as for the target (PAL-SD):
    • i50, Lower Field First.
  • Configure the monitoring system:
    • Set up the previewing/monitoring factors so that one can visually confirm the presence and quality-check the nature of interlacing.
      • Monitor-screen
        • Ensure it is clear and bright
      • Premiere: Program Monitor (PM):
        • Ensure it is at least “100%” big
          • Ideally, in [Fit] mode, scale it bigger than 100% – implies having a suitably large external screen, or the PM expanded to full-screen in the workspace.
          • Otherwise, instead put it in [100%] mode, and just be aware that it is cropping.
        • QuickMenu (at top-right of PM): [Display Both Fields]
          • This option is unavailable from PM>RightClick.
        • Select Playback Resolution: [Full]
          • On my system, when I tried the only not-Full option, namely [Half], the playback image screwed up
            • Had the appearance of a framing bug…
  • Select a suitable test-frame
    • Select a frame where there is dynamic (over time between frames) change, preferably due to motion.
      • At this (interlaced sequence with progressive clip) stage, motion will be represented as just a motion-blur.
  • Drag the FieldsKit ReInterlacer Effect onto the (p25) clip.
  • No proper re-nterlacing happens at this stage (duh!).
    • Dynamic objects in the test-frame still look motion-blurred.
  • Configure the ReInterlacer
    • Field Order: [Lower First]
    • Output Type: [= Create motion estimated fields]
      • This is not the default (oddly).  But it is the only proper way to get reinterlacing to happen!
    • Source Layer: [Video 1]
      • Since in my case I only had one video element.
  • Now the interlacing should be evident
    • Look for horizontal “comb-teeth” (“combing”) effects.
    • On a progressive monitor (as on a PC and typical external monitor) the combing may look like a degradation, but on an interlaced screen (as with an old analog TV) the reverse will be true.
  • Inspect the result on an interlaced TV
    • Burn a test-DVD
      • Ensure it is likewise interlaced
        • I think Adobe Media Encoder defaults to Progressive, even for a SD DVD.
    • Try and find an analog interlaced TV
      • This is the “lowest common denominator” – but we should allow for it.
        • Some audients may have existing analog projectors or favourite old TVs…
      • Finding such a device may be difficult – hardly anyone has analog TVs anymore.
    • Play the DVD on the TV, especially looking to see how dynamic (e.g. moving) elements appear.
      • Motion should be smooth, not flickering…

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