The TrafBox and related fields encapsulate metadata specific to the requested fragment and track. The syntax of the TrafBox field is a strict subset of the syntax of the Track Fragment Box defined in [ISO/IEC-14496-12].
TrafBox (variable): Top-level metadata container for track-specific metadata for the fragment. The following fields are required and MUST be present in TrafBoxChildren: TfhdBox, TrunBox.
TrafBoxLength (4 bytes): The length of the TrafBox field, in bytes, including the TrafBoxLength field. If the value of the TrafBoxLength field is %00.00.00.01, the TrafBoxLongLength field MUST be present.
TrafBoxLongLength (8 bytes): The length of the TrafBox field, in bytes, including the TrafBoxLongLength field.
The syntax of the fields defined in this section, specified in ABNF [RFC5234], is as follows:
TrafBox = TrafBoxLength TrafBoxType [TrafBoxLongLength] TrafBoxChildren TrafBoxType = %d116 %d114 %d97 %d102 TrafBoxLength = BoxLength TrafBoxLongLength = LongBoxLength TrafBoxChildren = 2 *( TfhdBox / TrunBox / VendorExtensionUUIDBox )