Standards

The IETF MoQ working group standardizes Media over QUIC. This project tracks that work and interoperates with it, while shipping a simpler profile you can use today.

Spec	Scope	Here
moq-transport	The IETF pub/sub protocol	Drafts 14 through 22 negotiated by ALPN; moq-lite is a forward-compatible subset
MSF	The IETF catalog format	Read and written; broadcasts ending in .msf select it
LOC	The IETF low-overhead container	Supported as a hang container kind
moq-lite, hang, e2ee, and friends	This project's own drafts	Normative for the implementation, published to the datatracker from drafts/

moq-transport

moq-transport is the full protocol: namespaces (broadcasts) that several publishers may share, sub-groups for layered codecs, object-level metadata and gaps, FETCH for ranges of history, joining fetches, PUBLISH push, and pausing. moq-lite keeps the parts a CDN can implement without conflicts and maps everything else to "not supported" or a harmless equivalent. The moq-lite page lists the differences.

On draft 19 and later, a requester can FIN its request stream while its subscription or namespace advertisement stays active. Cancellation uses RESET_STREAM or STOP_SENDING. Subscription REQUEST_UPDATE can change subscriber priority; other changes are refused with NOT_SUPPORTED and end the subscription with UPDATE_FAILED. Drafts 17 and 18 retain FIN cancellation.

Rust and JavaScript subscribers accept object extension blocks up to 64 KiB. This is an implementation limit, not a limit in the IETF draft. A larger declared block stops its subgroup stream with MALFORMED_TRACK before reading the block; other groups and the session stay open.

Rust and JavaScript read an incoming padding stream (draft-18 and later) to the end and discard it, without sending STOP_SENDING. A unidirectional stream type the negotiated draft does not define, or a SUBGROUP_HEADER type it marks invalid, closes the session with PROTOCOL_VIOLATION, as the draft requires.

An IETF publisher declares the track's default priority in SUBSCRIBE_OK or PUBLISH when that draft carries track properties. Groups without a priority flag inherit it. If the property is absent, the IETF wire default of 128 maps to model priority 127, where higher values are served first. A track that never sets a priority is 127 as well, so it goes out as 128 on IETF and 127 on moq-lite.

On drafts 14–19, the Rust publisher answers a standalone FETCH within one group from the cache. A relay fetches a missing group upstream with a FETCH of that one whole group, and an upstream refusal is the refusal the fetcher sees. Once its last reader leaves, the relay cancels the upstream fetch, even before FETCH_OK, and aborts an incomplete group instead of caching it as whole. Drafts 14–16 use FETCH_CANCEL; drafts 17–19 stop and reset the request stream. A range touching several groups is refused with NOT_SUPPORTED, as is any FETCH on draft-20 and later, which moved the range into LOCATION_FILTER. A standalone FETCH carries no timestamps, since no SUBSCRIBE_OK declared a timescale for it.

On drafts 14–19, the Rust publisher also serves relative and absolute joining FETCH requests for NextObject subscriptions, for the subscription group's saved prefix only, while the subscription delivers later objects. One reaching back to earlier groups is refused with NOT_SUPPORTED. Draft-20 uses subscription fills instead. JavaScript publishing refuses every FETCH with NOT_SUPPORTED; Rust and JavaScript subscribers request unfiltered delivery on older drafts because they do not issue joining fetches. Other publishers may replay a cached backlog for that filter; selecting the next group instead would leave static tracks waiting for a group that never arrives.

A moq-lite datagram is a single-frame group, so on moq-transport it travels as an OBJECT_DATAGRAM at object 0 whose Group ID is the sequence, and a relay forwards it without renumbering. A datagram carrying any other Object ID, or a status other than Normal, is dropped. JavaScript does not yet carry datagrams on moq-transport.

A client may present one credential in its SETUP with the AUTHORIZATION TOKEN option. The server reads a value (USE_VALUE, or REGISTER, which it treats as a value since it advertises no token cache) and hands its Token Type and bytes to the application unverified; a relay forwards them to its auth server. An alias reference (DELETE, USE_ALIAS) closes the session with PROTOCOL_VIOLATION, a structure that does not decode with KEY_VALUE_FORMATTING_ERROR, and a second token is refused. An AUTHORIZATION TOKEN parameter on a request is read and ignored: the session's credential is what authorizes it.

A legal request that is not served is refused on its own with NOT_SUPPORTED, leaving the session open: a SUBSCRIBE with FORWARD=0, a SUBSCRIBE or FETCH carrying Range Filters (no MAX_FILTER_RANGES is advertised), a FETCH carrying FILL_TIMEOUT (Timed-Out gaps are not written), TRACK_STATUS, SUBSCRIBE_TRACKS (draft-18 and later), and the FETCH forms above. NEW_GROUP_REQUEST is ignored, as the draft allows a publisher without dynamic groups to do. A parameter the negotiated draft does not define still closes the session with PROTOCOL_VIOLATION, as the draft requires.

Several project drafts extend the IETF wire without breaking it, since SETUP ignores unknown parameters: cluster routing hop lists, solicit to make announcements opt-in, hidden to keep .-named namespaces out of discovery, active-count to count the NAMESPACE messages before a SUBSCRIBE_NAMESPACE is caught up, and probe for bandwidth estimation. moq-e2ee is not a transport extension: it encrypts application payloads so relays still forward named tracks they cannot read.

MSF

The MoQ Streaming Format is a catalog, playing the role HLS playlists and SDP do elsewhere. It overlaps with the hang catalog and the two will likely converge. The tools track draft-01 and hide the version on the wire, so draft-00 catalogs still decode and init data always arrives inline. The stalled rendition hint is shared between the two formats.

LOC

The Low Overhead Container carries a timestamp and a few properties per frame with none of CMAF's per-frame moof cost. It is close to hang's legacy container and is selectable per track (container=loc in the GStreamer plugin).

Interop testing

moq-cli speaks every listed draft, picks the newest one the relay also supports, and prints it in the logs. Publish a test pattern and play it back:

ffmpeg -re -f lavfi -i testsrc=size=1280x720:rate=30 -f lavfi -i sine=frequency=440 \
    -c:v libx264 -preset ultrafast -tune zerolatency -g 60 -c:a aac \
    -f mpegts -pes_payload_size 0 -muxdelay 0 - \
| moq --connect https://relay.example.com --broadcast test.hang import ts

moq --connect https://relay.example.com --broadcast test.hang export ts | ffplay -

Add --connect-tls-insecure for a self-signed relay on your own test network (it accepts any certificate, so never point it at a remote relay) and RUST_LOG=info,moq_net=debug to see the negotiated version. Behavior worth knowing when pointing another implementation at ours: we announce every namespace we can offer unsolicited and ask for every prefix we may discover; set the solicit SETUP option to make us wait to be asked. Single-track PUBLISH offers are declined; announce a namespace and serve the resulting SUBSCRIBEs instead.