Export times for 4k to 1080p conversion

Discussion in 'Digital Video' started by jamisonbaines, Apr 13, 2017.

  1. jamisonbaines macrumors regular

    Dec 14, 2007
    Editing drone footage on my 2011 MBP and I'm getting about 1 hour export times for 10 minutes of video.

    This is on iMovie 10 with a quad core i7 @ 2GHz. I'm not doing anything intricate as far as editing is concerned, just a few cuts and transitions, adding music and exporting to 1080p but in the future I might do more.

    What I'd like to know is how much better export times would I get with newer hardware (say a 5k iMac with the 4GHz i7). Also on my current system would I be better off converting the files to 1080p in another application before editing? Would handbrake do this?
  2. joema2 macrumors 65816


    Sep 3, 2013
    On my 4Gh 2015 iMac 27 using FCPX it takes 21 min. to export 30 min of 4k H264 footage from a 4k timeline. So that is faster than real time. Your export is 1/6th real time, which seems abnormally slow. I don't use iMovie so I don't know what the export performance difference is (if any) vs FCPX.

    In FCPX if I use that 4k content on a 1080p timeline this greatly speeds up export to 1080p, yet still preserves the original 4k detail for zooming and cropping. The same 4k 30 min content on a 1080p timeline took 9 minutes to export to H264 1080p, or over 2x faster, or about 3x real time. I don't know if that's an option for iMovie.

    If you are using compute-intensive effects such as stabilization those must be fully rendered for export which can take a long time. One test would be trying to export a 10 min test clip without any effects. That will determine if the slow performance is due to encoding vs. effects rendering.
  3. Unami, Apr 15, 2017
    Last edited: Apr 15, 2017

    Unami macrumors 6502a

    Jul 27, 2010
    yes, a 4ghz imac for example will be significantly faster (at least double, might be more in specific areas like video encoding) than a 2011 mbp.

    of course it depends on the codec you're using, but i'd just guess it's h.264 (typical .m4v or .mp4 files)

    try exporting to prores. if the prores-export noticeable faster, then it's the h.264 encoding that takes so much time. you could then feed the prores file to handbrake and see, if that's overall faster.

    if the prores export also takes forever, then it's probably the resizing done in imovie that takes so much time. then you could indeed try something like mpeg streamclip or compressor (or even handbrake, if editing in h.264 is fast enough - otherwise use prores), to encode your footage to a 1080p file first.

Share This Page