Frame rate options overview
There are two ways to modify the rate at which a transcoded file plays back. You can apply speed effects to slow down or speed up playback, or you can change the frame rate of the transcoded file (which may or may not have an effect on playback speed). If you do change the frame rate, there are special options for working with interlaced footage, including deinterlacing and reverse telecine.
The controls that make speed modifications are located in the General inspector and in the Video inspector.