TRACK_STATUS — MoQT draft-11 §8.18.

A publisher sends a 'TRACK_STATUS' message on the control stream in response to a TRACK_STATUS_REQUEST message.

TRACK_STATUS Message {
  Type (i) = 0xE,
  Length (i),
  Request ID (i),
  Status Code (i),
  Largest Location (Location),
  Number of Parameters (i),
  Parameters (..) ...,
}

Figure 20: MOQT TRACK_STATUS Message

Request ID: The Request ID of the TRACK_STATUS_REQUEST this message is replying to Section 8.18.
Status Code: Provides additional information about the status of the track. It MUST hold one of the following values. Any other value is a malformed message.

0x00: The track is in progress, and subsequent fields contain the highest group and object ID for that track.

0x01: The track does not exist. Subsequent fields MUST be zero, and any other value is a malformed message.

0x02: The track has not yet begun. Subsequent fields MUST be zero. Any other value is a malformed message.

0x03: The track has finished, so there is no "live edge." Subsequent fields contain the highest Group and object ID known.

0x04: The publisher is a relay that cannot obtain the current track status from upstream. Subsequent fields contain the largest group and object ID known.

Any other value in the Status Code field is a malformed message.

TODO: Auth Failures

Largest Location: represents the largest Object location observed by the Publisher for an active subscription. If the publisher is a relay without an active subscription, it SHOULD send a TRACK_STATUS_REQUEST upstream or MAY subscribe to the track, to obtain the same information. If neither is possible, it should return the best available information with status code 0x04.

The Parameters are defined in Section 8.2.1.