klV

KLV stands for Key-Length-Value, a simple data-encoding method used to embed metadata in multimedia streams and other binary protocols. A KLV data item is composed of three parts: a key, which uniquely identifies the type of metadata; a length field, specifying how many octets follow in the value; and the value, a binary payload carrying the actual data. In many implementations, the key is a fixed-length identifier, commonly 16 bytes, although shorter or vendor-specific keys may be used. The length field uses a variable-length encoding similar to BER, allowing compact representations for small values and extending to larger ones as needed. The value can represent a wide range of data types, including integers, strings, timestamps, or nested structures.

KLV is widely used to encode metadata for motion imagery and other sensor data, particularly within MISB (Motion Imagery Standards Board) standards. In MISB documents, KLV items are organized into local sets, with a hierarchy of keys defined in a metadata dictionary. A KLV stream can be nested, so a value may itself contain a sequence of embedded KLV triplets. The primary advantage of KLV is its simplicity and extensibility, enabling efficient transmission and parsing of heterogeneous metadata alongside video or other payloads. A limitation is that the meaning of each key and the interpretation of its value typically require external dictionaries or schemas, making interoperability dependent on shared key dictionaries.