Choppy 1080 Playback on iMac 27 (2017)

Discussion in 'iMac' started by JasonMovieGuy, Nov 1, 2017.

  1. JasonMovieGuy, Nov 1, 2017
    Last edited: Nov 1, 2017

    JasonMovieGuy macrumors regular

    Jan 11, 2010
    Chicago, IL
    Just got the new iMac 27 (580, 2TB Fusion) - and was doing a test on 1080 video that would play choppy on my old 2009 iMac. Sadly, this same video is doing the SAME thing on this brand new computer that's not only supposed to handle 1080, but 4K as well. It's a MKV file, currently getting converted into an MP4 on Handbrake.

    Why would this occur on this machine? I bought this computer specifically to have smooth editing and playback for HD videos, and it's already acting up. I am tempted to return this but wanted some advice before I call Apple Care. Could the choppy playback be a result of me filming it years back? Or perhaps because my computer still only has 8GB of RAM and I have not added my new RAM yet because it has not arrived.

    It plays fine until I attempt to fast forward it to a different part. It's only a 20 minute video. Any advice would be appreciated.

    UPDATE: I transferred it through handbrake, and it plays smooth as butter in MP4 format. Still, strange the raw MKV file was choppy. Not sure if that is because of the specific file, or something else.
  2. joema2 macrumors 68000


    Sep 3, 2013
    There is no need to return your iMac because it won't smoothly play a certain .MKV file. It might not play well on a Mac Pro or even a Windows machine.

    There are a wide variety of video codecs and formats. .MKV is just a container -- you can't tell what's inside the file without examining it a tool like MediaInfo: or Invisor:

    With Invisor you can examine in a side-by-side spreadsheet format the characteristics of several video files. E.g, you could drag the MP4 and MKV version of this file to Invisor and examine the exact differences, or post those here.

    In my experience Quicktime Player won't handle most MKV files -- I play them with VLC. Are you using VLC or some other player? However even on my overclocked Windows machine if I fast forward a MKV file in VLC, the image breaks up and sometimes does not recover. This is why I never voluntarily use MKV.

    A Google search shows many references to people having problems smoothly playing MKV files from VLC on a variety of machines -- including Windows.
  3. gian8989 macrumors 6502

    Oct 23, 2015
    You can also try IINA if VLC is giving you problems
  4. JasonMovieGuy thread starter macrumors regular

    Jan 11, 2010
    Chicago, IL
    @gian and joema2- thank you for the advice. I am glad it wasn't just my VLC player that breaks the image up. And I'll try that other link.
  5. gian8989 macrumors 6502

    Oct 23, 2015
    Unfortunatelly there hasn't been a decent player around since Mplayerx decided to be garbage and install other software (mackeeper) without the user autorization.
    Vlc to work in a decent way needs some tuning in video option.
    IINA is not even 1 year old but it is already better in my opinion.
  6. thejackD macrumors newbie

    Oct 29, 2017
    you can use use Subler it's fast and easy

Share This Page

5 November 1, 2017