Some embodiments provide a method that receives the addition of a video clip to a composite video project. The video clip has a sequence of video images at a first frame rate and the composite video project has a second frame rate for outputting video images. When the first frame rate does not match the second frame rate but is within a threshold of the second frame rate, the method generates output video images for a particular duration of the composite video project at the second frame rate by using each of the video images of the video clip once during the particular duration. When the first frame rate is not within the threshold, generating output video images for the particular duration of the composite video project at the second frame rate by using at least one of the video images for each output video image over the particular duration.