Some embodiments provide a method for defining a data structure for representing a media file imported into a media-editing application. The method defines a reference to an original version of a media file. The method defines references to one or more transcoded versions of the media file. Each of the transcoded versions has a different resolution. The method defines a set of metadata storing information regarding the media file. In some embodiments, the media file includes both audio and video. The method defines a video clip data structure for the media file that references the first data structure and an audio clip data structure for the media file that also references the asset data structure. The method defines a media clip data structure that contains the video clip data structure and the audio clip data structure. The media clip data structure is for editing into a composite video presentation.