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Interlacing issues

Discussion in 'Inspire 1 Help' started by Michael Edward Surcombe, Nov 13, 2015.

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  1. Michael Edward Surcombe

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    I'm shooting on the X3 and experiencing some bad issues when submitting for broadcast.
    This video is typical:

    Check out the shocking strobing on the sharp lines (and there's also some really bad moire on the rooftop)
    Original is shot 25p with 0 sharpening. I'm not certain of the workflow in post but it's likely to have been converted to 25i at some point.

    Are we stuck with this or are there ways to avoid it, either in acquisition or post?
     
  2. The Editor

    The Editor Moderator
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    Yes, hello and welcome to the forum.
    Thanks for introducing yourself. :rolleyes:

    It would help if you explained your workflow from how you shoot to acquisition and export for handover.

    Moved thread to 'Help' section.
     
  3. Michael Edward Surcombe

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    re acquisition, I'm shooting with ND at roughly 1/60 shutter. 25p.
    It's notable that both the worst instances of these issues have been shooting normal colour rather than the log colour I prefer to shoot in.

    Another mystery - when I view that exact shot as a source file I'm seeing none of the aliasing and only minor moire. Certainly nothing like the end result.
    However, one of my customers instantly had problems as soon as he put the material on a FCP10 timeline, even a progressive timeline.

    What I really need to nail is what in the post production (which I'm not involved in) might be causing these horrendous artefacts.
     
  4. Michael Edward Surcombe

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    p.s. it may well be nothing to do with interlacing. It was just my first reaction that it looked like some kind of field issue
     
  5. The Editor

    The Editor Moderator
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    Why not ask your post house? They should know what they are doing in the pipeline?

    I'll try again......
    What resolution are you shooting in?
    What timeline settings are you putting this on when the problem manifests?
    What are your export settings (codec, wrapper etc) for handover to your post house or are you just dumping the files and giving it to them to ingest.?
     
  6. Michael Edward Surcombe

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    1920/1080 MOV

    The post people are mystified too unfortunately, so I'm trying to get to the bottom of it. My involvement ends when I deliver a file for ingest but, as I say, simply putting the file on a timeline set to the media's settings starts throwing up the artefacts.

    My only thought at the moment is to bring the sharpness down to -1 but I really do find it too muddy and want to avoid that if at all possible.
     
  7. The Editor

    The Editor Moderator
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    This appears to be an issue with how your NLE is dealing with the footage. Can you try converting your raw footage first into a proprietary codec before placing on the timeline and see if that solves the issue?
    The X3 is bad but it isn't THAT bad!
     
  8. Michael Edward Surcombe

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    That's reassuring!
    Thanks, I'll try that now.

    In general, do you think reducing sharpness would help?
     
  9. The Editor

    The Editor Moderator
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    You can try shooting at -1 or -2 and then bring it up in post which usually gives better results (the X3 over sharpens at default settings) but moiré is an issue and nothing can be done about the GOP structure which will cause intraframe pulsing every 8 frames - we are stuck with that.
    Just out of interest, I notice your footage was distributed via BBC. Do you know if they converted this to closed GOP MPEG2. If they did that can cause issues with Inspire footage.
     
  10. Michael Edward Surcombe

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    I don't know that, but I'll certainly try to find out. The lingering mystery is why on my FCPX I can't replicate the problem, whereas on my editor's FCP7 there are artefacts as soon as it's on the timeline. Both are playing native H264 with no settings changes from the master.

    As a matter of interest, what the feelings on the X5 with regard to these problems?
     
  11. Kilrah

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    FCP7 is an obsolete piece of "*ç%& by now, it's unfortunate some people are still sticking with it. Their problem when they have such issues that are way too common with it. When it was last updated progressive video was barely a thing, and it has always had trouble with it.

    It looks like it considers the video as interlaced, and maybe with the fields swapped too. Adjusting sharpness won't help beyond making your footage mushy in addition to the current problem...

    Maybe there's a setting in FCP to tell it how to interpret the footage manually. If not, I guess a transcode would be required. If you used the DJI transcode tool to make ProRes files it should take it correctly as that's its "native" format. Of course they'll be huge and impractical, but if there's no other choice...
     
  12. Michael Edward Surcombe

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    A bit more news on this....

    The problems seem to occur when the footage is downconverted to SD, either a preview window on NLE or (as in the post-production for online publication here) after mastering. It looks like something just can't cope with high level of detail as encoded by the X3 with 0 sharpening.

    So, I'm guessing a -1 or less sharpening will help.

    Also, is it coincidence that this problem has never been revealed in LOG footage?
     
  13. The Editor

    The Editor Moderator
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    Bad down conversion then.
    Push it through VirtualDub using resize/Lanczos3 (don't use bicubic)
     
  14. DennisR

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    I always convert my footage from the card to Pro res with Quicktime Pro. I never drag and drop directly to the timeline. FCP7 doesn't like H264.