Track Namespace Structure — MoQT draft-21 §8.7.

Track Namespace (Section 2.4.1) is encoded as follows:

Track Namespace {
  Number of Track Namespace Fields (vi64),
  Track Namespace Field (..) ...
}

Number of Track Namespace Fields: A variable-length integer specifying the number of Track Namespace Fields in the Track Namespace.

Each Track Namespace Field is encoded as follows:

Track Namespace Field {
  Track Namespace Field Length (vi64),
  Track Namespace Field Value (..)
}

Track Namespace Field Length: A variable-length integer specifying the length of the Track Namespace Field in bytes.
Track Namespace Field Value: A sequence of bytes that forms a Track Namespace Field.

Each Track Namespace Field Value MUST contain at least one byte. If an endpoint receives a Track Namespace Field with a Track Namespace Field Length of 0, it MUST close the session with a PROTOCOL_VIOLATION.

If an endpoint receives a Track Namespace consisting of greater than 32 Track Namespace Fields, it MUST close the session with a PROTOCOL_VIOLATION.

The maximum total length of a Full Track Name is 4,096 bytes. The length of a Full Track Name is computed as the sum of the Track Namespace Field Length fields and the Track Name Length field. The length of a Track Namespace is the sum of the Track Namespace Field Length fields. If an endpoint receives a Track Namespace or a Full Track Name exceeding 4,096 bytes, it MUST close the session with a PROTOCOL_VIOLATION.