[Moq] MSF updates

["Law, Will" <[e-mail]>]

We are pleased to announce that the -01 update to the MOQT Streaming Format draft has been released and is available at

https://datatracker.ietf.org/doc/draft-ietf-moq-msf/01/
This is a significant improvement in the specification over draft-00 . Below is a summary of the new features and syntax changes between -00 and -01.
MSF is being actively developed. Please file issues<https://github.com/moq-wg/msf/issues>. We are especially interested in feedback from early implementations.
New Features
1. End-to-End Encryption (Section 4.3, expanded)

A full encryption framework was added built on MoQ Secure Objects. New subsections cover:

  *   Encryption scheme signaling — scheme, cipher suite, key ID, and base key signaled in the catalog
  *   Key management — keyId scoping (per-track, per-session, or multi-session)
  *   Recommended scheme — moq-secure-objects with AES-128-GCM-SHA256 (mandatory), AES-256-GCM-SHA512, and AES-128-CTR-HMAC-SHA256-80
  *   Encrypted object structure — immutable headers (Group/Object ID) stay plaintext; payload + private extensions (type 0xA) are encrypted

2. Publish Tracks / Subscriber-Initiated Publishing (Section 5.1.5)

A new publishTracks array at the root catalog level allows publishers to define tracks to which subscribers publish data back (logs, metrics, QoE). This enables bidirectional communication.

3. Log Track (Section 9, new)

A new track type (packaging: "moqlog", role: "log") for subscribers to send diagnostic/operational log data upstream. Group ID = capture timestamp (µs since epoch); Object ID distinguishes sub-microsecond entries. Payload format references [MOQLOG], with OpenTelemetry-aligned fields (TraceID, SpanID, etc.).

4. Metrics Track (Section 10, new)

A new track type (packaging: "moqmetrics", role: "metrics") for subscribers to publish QoE/performance metrics. Group ID = capture time (ms epoch); Object 0 holds timestamp + attributes, Object 1+ hold individual metrics (Gauge/Counter, int or float64). References [MOQMETRICS].

5. Media Timeline Template (Section 7.4, new)

For content with fixed-duration segments, a compact inline template field on a track replaces the need for a separate media timeline track. The template is a 6-element JSON array [startMediaTime, deltaMediaTime, startLocation, deltaLocation, startWallclock, deltaWallclock] from which clients compute all entries algebraically.

6. MSF URL Scheme (Section 11.1, new)

A formal ABNF grammar for MSF URIs (moqt://authority/path#msf:namespace--name&params). Includes:

  *   Fragment type msf registered in the MOQT URI Fragment Types registry
  *   wallclock-range reserved fragment parameter for subclip selection
  *   MSF Namespace-Name String Encoding (Section 11.1.2)
  *   Variable substitution via URI fragment key-value pairs (Section 5.4)

7. Token-Based Authorization Framework (Section 11.4, new)

Full authorization workflow covering discovery (via authInfo catalog field), token acquisition (OAuth 2.0, out-of-band, URI parameters), token presentation in MOQT control messages (CLIENT_SETUP, SUBSCRIBE, FETCH, PUBLISH, etc.), and failure handling with retry/backoff guidance. Supports Privacy Pass and CAT schemes.

8. Variable Substitution (Section 5.4, new)

Catalog field values can contain %variable% placeholders resolved from the URI fragment at delivery time. Enables per-viewer customization (personalized ads, watermarking, logging IDs) from a single cached catalog.

9. Catalog Compression (Section 5.5, new)

Catalogs and timeline track payloads can be GZIP-compressed. Signaled via new MOQT Track Property (MSF_COMPRESSION on the track for uniform compression) or Object Property (per-object, for mixed compressed/uncompressed within a track). All implementations MUST support GZIP (value 1).

10. IANA Registries (Section 14, expanded)

Three new registries defined: "MOQT URI Fragment Types", "MSF Event Timeline Types", MSF_COMPRESSION Track Property, and MSF_COMPRESSION Object Property.


Catalog Syntax Changes

1.  Restructured Root Catalog Fields

v00 had a flat list of fields; v01 splits them into Root Catalog Fields (Section 5.1) and Track Object Fields (Section 5.2):

v00 field

v01 location/change

deltaUpdate (array of operations)

Moved to root; restructured as {"op": "add"/"remove"/"clone", "tracks": [...]} objects

addTracks, removeTracks, cloneTracks as separate top-level fields

Replaced by unified deltaUpdate array with op field

initializationData inline in track

Replaced by initializationRef (pointer) + new initializationDataList array at root

bitrate (single field)

Split into maxBitrate (required for A/V) and avgBitrate (optional)


2. New Track Object Fields

The following fields are new in v01:

  *   buffers — object with target, min, max buffer durations (ms); mutually exclusive with targetLatency
  *   template — inline media timeline template (6-element array)
  *   parentNamespace — for clone operations in delta updates (previously only parentName existed)
  *   connectionURI — MOQT endpoint for publish tracks
  *   token — auth token for publish track authorization
  *   encryptionScheme, cipherSuite, keyId, trackBaseKey — encryption parameters
  *   authInfo — authorization requirements object (scheme → config)
  *   accessibility — array of {scheme, value} descriptors for CEA-608/CEA-708 captions
  *   maxGOPDuration — maximum interval between random access points (ms)
  *   maxGroupDuration — maximum MOQT Group duration (ms)

3. Delta Update Restructuring

v00 used separate top-level fields (addTracks, removeTracks, cloneTracks, deltaUpdate as a boolean). v01 consolidates these into a single deltaUpdate array of operation objects, each with "op": "add"|"remove"|"clone" and a "tracks" array. The cloneoperation now also supports parentNamespace.

4. Object Numbering Formalized (Section 6.2, new)

Object ID MUST start at 0 and increment monotonically by 1 within a Group — this was implicit in v00.

5. Media Timeline Entry Format (Section 7.1.1, renamed)

The entry format is now labeled "Explicit entry format" to distinguish it from the new template approach.

6. New Catalog Examples (Section 5.6)

Nine new examples added beyond v00's set:

  *   Encrypted Audio/Video Tracks
  *   Media timeline template
  *   Video track with embedded captions and SCTE-35 events
  *   Video track with CEA-708 captions
  *   Variable substitution for personalized delivery
  *
Time-aligned Audio/Video with Authorization
  *   Publish tracks for logs and metrics

Cheers
Will