How to skip around a movie

A while back I created an interface for marking events on a video. The videos are of patients walking in a hallway. The interface lets me assign numeric codes to segments of a video that indicate when the patient is walking, turning, standing still, etc. I use the PlayMovieAction command to skip across short and long stretches of a video using the action:

PlayMovieAction /Z step = frameStep

Using frameStep = 1 moves the movie forward 1 frame
Using frameStep = 500 moves the video forward 500 frames

In an older version of my Mac (around 2014-2015), skipping 500 frames took no time because the video window did not show intermediate frames. On my current Mac (OS 10.13, High Sierra), skipping large numbers of frames takes much longer. The video window plays, at some accelerated rate, the video between the current position and the final one.

I imagine this may be due to a change in Quicktime, and if so it?s likely that there is nothing i can do about this. I?d like to ask:

- Does anyone know a way to get Igor to skip from one movie frame to another one without playing the in-between frames?

- The Help section says that the PlayMovieAction functionality depends on Quicktime and will therefore be deprecated at some point. Is there a new way to open and play movies in Igor on a Mac that I can use?


I don't have an immediate answer. However, would the speed be improved when you would do a HIDE of the video window, skip forward/backward, and then SHOW the movie window?