For each video, an Image window can be opened to display the video frame that corresponds to the current reference frame. Notice that the video frame number and reference frame number are displayed in the title bar of each Image window.
The Video Control window is designed to change the current reference frame, which will cause all the Image windows to display videos at their own corresponding frames. If the videos are properly synchronized, the images displayed in different Image windows are taken at the same moment.
Videos can be played forward or backward continuously or one frame at a time. Note that when you press on one of the controls to play a video, all opened videos, that is all videos that have been added to the project, are played in the same direction and speed. When you press play, the video plays to the end, then returns to the starting point and continues to play over and over until stopped.
Photo4D includes Auxiliary windows to help view different frames in different videos at various moments.