Black Video Screen Playback

[George2000]

Hello,
I am running Pro Tools 2018.12.0 on MacOs High Sierra on a 2013 Mac Pro with 32 GB of RAM.

I am getting a "black" video window on playback.

When I insert a video into the timeline, it will playback in the video window if the video is at the start of the session or if a time selection is made in the video track. The video window will remain black though if I just place my cursor in the video timeline and playback from that point or if I drag the video to another spot on the timeline and begin playback.

Note that the black screen only occurs if the video is at 30fps. 29.97fps videos play back correctly. The video is using H.264. Curiously this same video plays back fine on two older Mac minis with the same OS!

I realize that Avid recommends Dnxhd but when I convert to that the whole video is a black screen in both Quicktime and Pro Tools.

I downloaded the codecs package from here: http://avid.force.com/pkb/articles/e...Time-Codecs-LE

Any help would be greatly appreciated.