The MoofBox field and related fields encapsulate metadata that is specific to the requested fragment. The syntax of MoofBox is a strict subset of the syntax of the Movie Fragment Box that is specified in [ISO/IEC-14496-12].
MoofBox (variable): The top-level metadata container for the requested fragment. The following fields are required and MUST be present in MoofBoxChildren: MfhdBox and TrafBox.
MoofBoxLength (4 bytes): The length of the MoofBox field, in bytes, including the MoofBoxLength field. If the value of the MoofBoxLength field is %00.00.00.01, the MoofBoxLongLength field MUST be present.
MoofBoxLongLength (8 bytes): The length of the MoofBox field, in bytes, including the MoofBoxLongLength field.
The syntax of the fields that are defined in this section, specified in ABNF [RFC5234], is as follows.
MoofBox = MoofBoxLength MoofBoxType [MoofBoxLongLength] MoofBoxChildren MoofBoxType = %d109 %d111 %d111 %d102 MoofBoxLength = BoxLength MoofBoxLongLength = BoxLongLength MoofBoxChildren = 2*( MfhdBox / TrafBox / VendorExtensionUUIDBox )