Quicktime File Format (2012-08-14).pdf

Movie AtomsOverview of Movie AtomsColor table atomSee “Color Table Atoms” (page 46) for a discussion of the color table atom.Compressed movie atomSee “Compressed Movie Resources” (page 117) for a discussion of compressed movie atoms.Reference movie atomSee “Reference Movies” (page 119) for a discussion of reference movie atoms.The Movie Profile AtomNote Profile atoms are deprecated in the QuickTime file format. The information that follows isintended to document existing content containing profile atoms and should not be used for newdevelopment.The movie profile atom summarizes the features and complexity of a movie, such as the required codecs andmaximum bit rate, in order to help player applications or devices quickly determine whether they have thenecessary resources to play the movie.Features for a movie typically include the movie’s maximum video and audio bit rate, a list of audio and videocodec types, the movie’s video dimensions, and any applicable MPEG-4 profiles and levels. This is all informationthat can also be obtained by examining the contents of the movie file in more detail. This summary is intendedto allow applications or devices to quickly determine whether they can play the movie. It is not intended as acontainer for information that is not found elsewhere in the movie, and should not be used as one.Note The fact that a feature does not appear in the profile atom does not mean it is not present inthe movie. The profile atom itself may not be present, or may list only a subset of movie features.The features listed in the profile atom are all present, but the list is not necessarily complete.When creating a profile atom, it is permissible to omit some features that are present in the movie, but it isrequired to fully specify any features that are included in the profile. For example, a movie containing videomay or may not have a video codec type feature in the profile atom, but if any video codec type feature isincluded in the profile atom, every required video codec must be listed in the profile atom.The movie profile atom is a profile atom ('prfl') whose parent is a movie atom. This is distinct from the trackprofile atom, whose parent is a track atom. The structure of the profile atom is identical in both cases, but thecontents of a movie profile atom describe the movie as a whole, while the contents of a track profile atom arespecific to a particular track.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.42