LOCMAF - Low Overhead CMAF for Media over QUIC

draft-einarsson-moq-locmaf-01 | Individual | published 2026-07-05 (41 pp) | Datatracker draft-einarsson-moq-locmaf-00 | Submitted 2 June 2026

Authors

• Torbjörn Einarsson (Eyevinn Technology) — wiki maintainer; author of moqlivemock + mlmtest interop client
• Hugo Björs (KTH) — first IETF MoQ-side artifact

Abstract

LOCMAF defines a compact wire format that enables streaming low-latency CMAF media over MoQ Transport with significantly reduced per-object overhead. The format carries CMAF chunk metadata as tagged fields while preserving sample data unchanged, with the receiver reconstructing functionally equivalent CMAF chunks suitable for MSE/EME playback pipelines.

Position in the design space

Format	Wire shape	MSE/EME compatibility	Standardization
CMSF	Full CMAF chunks (init + chunks per CMAF spec)	Direct passthrough to MSE	WG (draft-ietf-moq-cmsf-00)
LOCMAF	Tagged fields + unchanged sample data; receiver reconstructs CMAF chunk (canonical, byte-identical)	Reconstructed; MSE-compatible after receiver-side rebuild	Individual (draft-einarsson-moq-locmaf-01)
LOC	Codec-aware compact frame format	No (requires non-MSE pipeline)	WG (draft-ietf-moq-loc-03)
compressed-mp4	Varint-compressed fMP4 boxes (96 → ~21 bytes per fragment)	After decompression: MSE-compatible	Individual
moq-media-interop	LOC wire format for H.264/Opus/AAC	No	Individual, expired Apr 23

LOCMAF’s distinguishing choice: carry CMAF chunk metadata as tagged fields, preserve sample data unchanged, reconstruct the CMAF chunk receiver-side. This makes it transparent to MSE/EME consumers (the player still sees standard CMAF chunks) while removing redundant box headers from the wire. Two further properties frame it as a candidate CMSF packaging mode: it is end-to-end (relays forward the Object payload unchanged) and uses catalog-referenced init (relying on MSF -01’s initData type so cmaf and locmaf tracks can reference the same init).

Why this matters

• Eyevinn’s MoQ adoption path: Eyevinn’s existing CMAF-based pipeline (HLS/DASH origins + low-latency CMAF chunked encoding) needs a MoQ wire shape that doesn’t force re-architecting the player-side MSE/EME glue. LOCMAF preserves that.
• MSE/EME compatibility constraint: Safari (notably for FairPlay DRM) requires avc1/hvc1 sample entries with parameter sets in the decoder configuration record, not avc3/hev1 with inline parameter sets (see Tobbe’s moq-wg/msf Issue #153 Point 4). LOC’s self-initializing segments break this. LOCMAF can carry the parameter sets out-of-band as tagged fields and reconstruct an MSE-compatible CMAF chunk.
• Streaming Tech Sweden + IETF prior work: presented as a low-overhead extension to CMAF in pre-IETF venues; the -00 submission formalizes the proposal.

Status

• -01 published: 2026-07-05 (41 pp) — a major consistency rewrite; -00 submitted 2026-06-02
• Relationship to CMSF: CMSF registers LOCMAF as a locmaf packaging by normative reference (moq-wg/cmsf PR #27), so LOCMAF keeps its independent standalone-draft path rather than being folded into CMSF
• Implementation reports: LOCMAF v0.3 shipped in moqlivemock v0.12.0, with the codec extracted into the standalone Eyevinn/locmaf module; warp-player on the MSE/EME playback side

Recent Highlights

Day-by-day activity lives in the wiki log; this section keeps only durable milestones.

• draft-einarsson-moq-locmaf-01 cut 2026-07-05 (41 pp, a major consistency rewrite) — the individual draft “Low Overhead CMAF for Media over QUIC” by Torbjörn Einarsson (Eyevinn) and Hugo Björs (KTH), the first IETF artifact from the wiki maintainer.
• First implementation: LOCMAF v0.3 shipped in moqlivemock v0.12.0 with the codec extracted into the standalone Eyevinn/locmaf module, paired with warp-player for MSE/EME playback; the redesign drops initData compression in favor of catalog-referenced init via MSF -01’s initData type.
• Adopted into CMSF by reference (not folded in): CMSF PR #27 registers a locmaf packaging that points at the standalone LOCMAF draft (the approach Will Law suggested on CMSF Issue #24), so LOCMAF stays sovereign over the format while CMSF gains the mode — reversing the earlier “fold in and retire the standalone” plan.

Related drafts and concepts

• moq-loc — Low Overhead Media Container (WG, draft-02) — the LOC-family WG draft from which LOCMAF differentiates
• moq-cmsf — CMAF-compliant MSF (WG, draft-00) — the CMAF-equivalent reference point
• compressed-mp4 — Varint compression of fMP4 boxes (Mo Zanaty individual)
• moq-media-interop — LOC media wire format for H.264/Opus/AAC
• moq-transport — base wire protocol
• moq-msf — MSF packaging umbrella draft

Authors and stakeholders

• Torbjörn Einarsson — Eyevinn Technology, wiki maintainer
• Hugo Björs — KTH (Royal Institute of Technology), Stockholm

References

• draft-einarsson-moq-locmaf-00 on Datatracker
• moqlivemock / mlmtest — Tobbe’s interop client likely to be the first LOCMAF implementation