A subscriber issues a UNSUBSCRIBE_NAMESPACE message to a publisher indicating
it is no longer interested in PUBLISH_NAMESPACE, PUBLISH_NAMESPACE_DONE and
PUBLISH messages for the specified track namespace prefix.
The format of UNSUBSCRIBE_NAMESPACE is as follows:
UNSUBSCRIBE_NAMESPACE Message {
Type (i) = 0x14,
Length (16),
Request ID (i),
}
-
Request ID: The Request ID of the SUBSCRIBE_NAMESPACE (Section 9.23) being cancelled by this message.