IEC 62261-2 pdf download Television METADATA – Part 2: Data encoding protocol using key-length-value
This part of lEC 62261 defines an octet-level data encoding protocol for representing dataitems and data groups.This protocol defines a data structure which is independent of theapplication or transportation method used.
The standard defines a key-length-value (KLV) triplet as a data interchange protocol for dataitems where the key identifies the data, the length specifies the length of the data, and thevalue is the data itself.The KLV protocol provides a common interchange for all compliantapplications irrespective of the method of implementation or transport.
The standard also provides methods for combining associated KLV triplets in data sets wherethe set of KLV triplets is itself coded with KLV data coding protocol.Such sets can be codedin either full form (universal sets) or in one of four increasingly bit-efficient forms (global sets,local sets，variable-length packs, and fixed-length packs). The standard provides a definitionof each of these data constructs.The encoding octet range (length of the payload) specifiedin this standard may generate unusually large volumes of data.Consequently, a specificapplication of KLV encoding is capable of only a limited operating data range and thosedetails shall be defined in a relevant application document.
Of necessity, keys and other reference data have to be globally unique if clashes are to beavoided. The lEC will therefore,from time to time，designate other bodies to act as itsregistration authority and agent in this respect; it is important to note that, as a result of this,registrations will always contain the designator of the registration authority acting at the timeof registration and not that of the lEc(unless the lEC was acting directly as its ownregistration authority). A mixture of registration authority designators is therefore to beexpected.
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies.For undated references, the latest editionof the referenced document (including any amendments) applies.
ISO/IEC 8825-1:2002，(ITU-T X.690)，Information Technology – ASN.1 Encoding Rules -Specification of BasicEncoding Rules(BER),CanonicalEncoding Rules (CER), andDistinguished Encoding Rules (DER)
ANSISMPTE 298M:1997,Television – Universal Labels for Unique ldentification of DigitalData
Table 1 and Figure 1 present an introductory view of the KLV protocol for encoding data.Thedata encoded may be a single data item or a data group. The coding of data items isdescribed in Clause 4 while the coding of data groups is described in Clause 5 of thisstandard.
The KLV coding protocol is composed of a universal label (UL) identification key (UL key) followed by a numeric length (value length), followed by the data value.