Low Overhead CMAF for Media over QUIC (LOCMAF) rev 01 lands on the IETF Datatracker
This document specifies LOCMAF (Low Overhead CMAF for Media over QUIC), a compact packaging for low-latency CMAF media carried end-to- end as MoQ Transport (MOQT) Object payloads, with per-object overhead comparable to the Low Overhead Container (LOC). LOCMAF carries the CMAF chunk head metadata from a single moof (movie fragment) as a small set of tagged fields, while leaving the sample data (mdat) untouched. Boxes that may surround the moof in a CMAF chunk — styp (segment type), prft (producer reference time), and any number of emsg (event message) boxes — are carried verbatim, each through a generic box element (a genBox). The first Object of each MOQT group carries a full reference; subsequent Objects in the same group carry only the differences. The receiver reconstructs CMAF chunks that are decode-equivalent to the sender input, including the encryption metadata required by CMAF DRM (Common Encryption) pipelines, and a canonical byte-identical reconstruction — independent of the encoder's representation choices — is defined for conformance testing.
Draft Snapshot
- Draft:
draft-einarsson-moq-locmaf - Revision: 01
- Last updated: 2026-07-05
- Source: IETF Datatracker
Summary
This document specifies LOCMAF (Low Overhead CMAF for Media over QUIC), a compact packaging for low-latency CMAF media carried end-to- end as MoQ Transport (MOQT) Object payloads, with per-object overhead comparable to the Low Overhead Container (LOC). LOCMAF carries the CMAF chunk head metadata from a single moof (movie fragment) as a small set of tagged fields, while leaving the sample data (mdat) untouched. Boxes that may surround the moof in a CMAF chunk — styp (segment type), prft (producer reference time), and any number of emsg (event message) boxes — are carried verbatim, each through a generic box element (a genBox). The first Object of each MOQT group carries a full reference; subsequent Objects in the same group carry only the differences. The receiver reconstructs CMAF chunks that are decode-equivalent to the sender input, including the encryption metadata required by CMAF DRM (Common Encryption) pipelines, and a canonical byte-identical reconstruction — independent of the encoder's representation choices — is defined for conformance testing.
Analysis
This draft is directly relevant to the MOQ ecosystem and worth tracking because it reflects current protocol work or adjacent implementation guidance from the IETF process.
Abstract
This document specifies LOCMAF (Low Overhead CMAF for Media over QUIC), a compact packaging for low-latency CMAF media carried end-to- end as MoQ Transport (MOQT) Object payloads, with per-object overhead comparable to the Low Overhead Container (LOC). LOCMAF carries the CMAF chunk head metadata from a single moof (movie fragment) as a small set of tagged fields, while leaving the sample data (mdat) untouched. Boxes that may surround the moof in a CMAF chunk — styp (segment type), prft (producer reference time), and any number of emsg (event message) boxes — are carried verbatim, each through a generic box element (a genBox). The first Object of each MOQT group carries a full reference; subsequent Objects in the same group carry only the differences. The receiver reconstructs CMAF chunks that are decode-equivalent to the sender input, including the encryption metadata required by CMAF DRM (Common Encryption) pipelines, and a canonical byte-identical reconstruction — independent of the encoder's representation choices — is defined for conformance testing.