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Mocha tracking of a 4K image

May 22, 2013 5:03 AM



I have a 4k file of some R3D footage that I have run through RedCineX. I export it as a 4K DNxHD MOV file. I import this into Premier, make some cuts/edits and replace with an AE comp. In AE, I reset the footage scale from 46.9% to 100%, as premier was set to scale to fit project so I could make the edit and then placed within my 4096x2160 AE project.


I want to track this in mocha, and I use the MochaImportPlus plug in. If I do this, the footage in Mocha is a 1080 view of the 4K footage. If I take the comp in AE and render a 4K PNG Intermediate, import the sequence into the same AE comp and reopen the tracking in Mocha through MochaImportPlus, it opens the full 4K image.


Is there a way to do without the intermediate step?


Pierre Devereux

  • Currently Being Moderated
    May 22, 2013 6:36 AM   in reply to Pierre Devereux

    Not sure I follow you from the very beginning...

    1. DNxHD is literally for 720 and 1080 frame size only. Well, physically you can export larger frame, but every time I attempted to do that, DNxHD threw ugly artefacts...

    2. You shoot in 4k so as to get some room for panning and scaling in post, your working frame size is 1080. So, why do you downscale 4k footage to 1080?


    If it were me, I wouldn't transcode R3D footages for bringing them into PrPro at all (as we actually discussed). I'd rather set the Playback Resolution to 1/4 and make rough cuts. Then I would bring those cuts into AE and think of whether I really need to track 4k footage or 1080 intermediate since my AE comp is 1080.


    I'd also transcoded to JPEG 2000 rather than PNG. Mocha may have issues with reading high bit depth JPEG 2000, but you don't need high bit depth so as to do a tracking job.


    My five pennies...

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    May 22, 2013 7:00 AM   in reply to Pierre Devereux

    The 4K version of DNxHD to my knowledge actually only works inside Avid products. It's sort of a hacky implementation outside the original DNx spec. I guess you're out of luck on that one, so use another format as the cat man suggested.



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    May 22, 2013 8:41 AM   in reply to Pierre Devereux

    I'm not sure I follow the AE to Mocha workflow. In AE your comp should be the same size as your footage before you open and track in Mocha. If you do that you should be fine unless you're looking at the sequence in PPro instead of the footage.


    My usual workflow is to trim footage to eliminate the garbage, do the tracking, stabilization, keying that need to be done with full rez original or production codec transcoded footage, then move back to the editing bench.


    If you're ingesting footage on a Mac I'd take a look at Red Giant Bullet Proof as a solution for managing your original footage. There is a free public beta going on right now. Here's an article from my friend Stu about it.

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