Editing 4K video on iMac is slow

Discussion in 'Digital Video' started by alstar, Oct 27, 2016.

  1. alstar macrumors newbie

    Jun 12, 2012
    Hi Guys,

    I am experiencing major issues while editing my 4K videos coming from my iphone 7 plus. I have a late 2012 imac with 16GB of Ram and a i7 Intel core proc but the lag when editing the clips in Final Cut pro x 10.2.0 is so bad that the frames drop.

    I am using an external thunderbolt drive to work out of but the issue is kinda bad, any suggestions?
  2. Gwendolini macrumors 6502


    Feb 5, 2015
    Are you using the original files, proxies or optimised media?

    And why have you not updated to 10.2.3 when there was still the chance?
  3. e1me5 macrumors regular


    Jun 11, 2013
    Does your iMac have an SSD or a traditional hard drive? And where do you store those videos?
    I have a 2012 i7 15" non-retina Macbook pro and I have no problem editing 4k videos of different formats.

    FCPX 10.3 was also released yesterday, it should perform even better with 4k now.
  4. joema2 macrumors 65816


    Sep 3, 2013
    Editing H264 4K can be challenging on almost any machine and editing software. It is four times the data as 1080p, but your computer did not magically become four times as fast.

    The best solution is transcode those clips to proxy, which can be done during import or after import: https://support.apple.com/kb/PH12702?locale=en_US&viewlocale=en_US
  5. 3568378 Suspended


    Dec 30, 2015
    Orlando, FL
    What kind of hard drive is in your Mac? If it's a spindle drive or the slower fusion drive (or probably any fusion drive for that matter) I would say good luck. You might be able to work around that with an external SSD via Thunderbolt?
  6. sevoneone macrumors 6502

    May 16, 2010
    A single stream of 4k h.264 should not saturate an external HDD connected via Thunderbolt. If you making ProRes 422 optimized media it is probable. if it is a spinning disk you will want to use Proxy. Also, are you applying any sort of filters or processing to the video? If so, your gfx card and/or amount of video memory could be a bottleneck. What graphics chip and amount of video memory is in your iMac?
  7. northernmunky macrumors 6502a


    Jan 19, 2007
    London, Taipei
    Guys seriously, just tell the guy what he needs to know, theres nothing wrong with the hardware.

    Buddy, heres your answer. 4k natively will not playback at speed on a your machine, you need to edit using proxy files. That way you edit fast, by working with small managable file rather than the very large 4K footage natively.

    Assuming you are using FCPX then this is easy.

    More info here:
    And if you havent already done so make sure you create proxy media:


    And are using them (if you are set using 'original', then that is why your edit is slow):

  8. alstar thread starter macrumors newbie

    Jun 12, 2012
    Thanks this helps and yes I will use the proxy media capability of FCPx and it does make life better!

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