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

Profile Atom GuidelinesUniversal FeaturesNote A writer that records the MPEG-4 video profile feature is encouraged also to write the QuickTimeVideo Codec Type feature.Feature Value AlgorithmThe feature value is the profile_and_level_indication from the visual_object_sequence, as definedin specification ISO/IEC 14496-2, retrieved from the video parameters for the MPEG-4 video codec description.Reader ResponsibilitiesA reader of this feature code should compare the recorded value with the set of profiles and levels supportedby the reader.CommentsThis feature may be present only if MPEG-4 video is used. Normally, the video codec type profile entry will alsorecord that MPEG-4 video is present, unless no codec types are present (when, for example, an exhaustive listcannot be formed).MPEG-4 Video CodecContaining profile atomTrack (video), moviepart-ID0x20202020 (universal feature)feature-code'mp4v'feature-valueUnsigned int(32) where the least significant 4 bits holds the visual_object_type as found in theVisualObject (as defined in specification ISO/IEC 14496-2, subclause 6.2.2) found in the esds of theMPEG-4 video codec (QuickTime type 'mp4v') sample descriptionFeature ValuesThe least significant 4 bits hold the value. The most significant 28 bits of the feature value should be set to 0.The list of visual object type constants is defined in specification ISO/IEC 14496-2, subclause 6.3.2.Example: Video ID is indicated by the value 1.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.407