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

Profile Atom GuidelinesUniversal FeaturesWriter ResponsibilitiesA writer of the MPEG-4 Video Codec feature should record the 4 bits corresponding to thevisual_object_type found in the VisualObject within the ES_descriptor's videoDecoderSpecificConfig. The most significant 28 bits of the value should be set to 0.Note A writer that records the MPEG-4 Video Codec feature is encouraged also to write the QuickTimeVideo Codec Type feature.Feature Value AlgorithmThe MPEG-4 video codec is the 4 bits of the visual_object_type found in the VisualObject. See ISO/IEC14496-2, subclause 6.2.2. The VisualObject is found in the MPEG-4 Elementary Stream Descriptor Atomwithin the 'esds' sample description atom of the video sample description for the QuickTime video codecof type 'mp4v'.Reader ResponsibilitiesA reader of this feature code should compare the recorded value with the set of MPEG-4 video decoderssupported by the reader.CommentsBecause the QuickTime 'mp4v' codec may implement multiple video decoders defined in specification ISO/IEC14496 in the future, this feature allows the reader to determine the specific video decoder needed to interpretthe video bit-stream.MPEG-4 Video Object TypeContaining profile atomTrack (video), moviepart-ID0x20202020 (universal feature)feature-code'm4vo'feature-valueUnsigned int(32) where the least significant 8 bits hold the video_object_type_indicationfound in the VideoObjectLayer (Described in ISO/IEC 14496-2, subclause 6.2.3). The VideoObjectLayer2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.408