MPEG-4 video codec

Overview

Containing profile atom: Track (video), movie
part-ID: 0x20202020 (universal feature)
feature-code: 'mp4v'
feature-value: Unsigned int(32) where the least significant 4 bits holds the visual_object_type as found in the VisualObject (as defined in specification ISO/IEC 14496-2, subclause 6.2.2) found in the esds of the MPEG-4 video codec (QuickTime type 'mp4v') sample description

Feature Values

The 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.

Writer Responsibilities

A writer of the MPEG-4 Video Codec feature should record the 4 bits corresponding to the visual_object_type found in the VisualObject within the ES_descriptor’s video DecoderSpecificConfig. The most significant 28 bits of the value should be set to 0.

Feature Value Algorithm

The MPEG-4 video codec is the 4 bits of the visual_object_type found in the VisualObject. See ISO/IEC 14496-2, subclause 6.2.2. The VisualObject is found in the MPEG-4 Elementary Stream Descriptor Atom within the 'esds' sample description atom of the video sample description for the QuickTime video codec of type 'mp4v'.

Reader Responsibilities

A reader of this feature code should compare the recorded value with the set of MPEG-4 video decoders supported by the reader.

Comments

Because the QuickTime 'mp4v' codec may implement multiple video decoders defined in specification ISO/IEC 14496 in the future, this feature allows the reader to determine the specific video decoder needed to interpret the video bit-stream.