The photo track represents the flow of photos in your movie. Photos are connected by transitions. Each photo can have key frames which represent a particular cropping and view of the photo at a particular point in the timeline. The movie will connect the key frames as the movie plays and the resulting motion is called the motion path.

In the timeline, the blue lines represent motion paths and the orange lines represent transitions between the photos. The height of the blue lines represents the relative speed of motion at that particular time. When the blue line is down, there is no motion. When the blue line is up, there is motion. When the blue line is directed up or down, the motion is either speeding up or slowing down.

You can adjust the duration of an entire photo track to match the length of your music (see Stretching the duration of a photo track).