Overview
ISO/IEC TR 23091-4:2021 is a technical report that documents common industry practices for using video signal type code points (coding-independent code points, CICP) across production and distribution systems. It explains how video properties - such as colour primaries, dynamic range, transfer functions, colour representation and mastering display metadata - are expressed as metadata and conveyed across capture, production, and carriage chains to avoid misinterpretation or quality degradation.
Key topics and technical scope
- Video signal type combinations: Describes the limited subset of practical combinations used in real-world workflows (e.g., SDR vs HDR, narrow colour gamut vs wide colour gamut) and highlights unlikely combinations to avoid.
- Colour coding characteristics: Defines how colour gamut, primaries, transfer/optical functions (OETF/EOTF/OOTF), chroma sampling and video range are represented and combined as code points.
- Mastering display colour volume (MDCV): Guidance on expressing mastering display colour volume metadata used by colourists and post-production tools.
- Workflow domains and carriage: Discusses how metadata is carried across domains (capture, production, distribution) and over interfaces used in industry workflows (e.g., SDI variants, file formats, bitstream VUI/SEI).
- Interoperability and automation: Advice for tool and system developers to automate content handling consistently across domains and avoid processing mistakes.
- Normative references and alignment: Links to related codec and metadata standards (Rec. ITU‑T H.264/AVC, H.265/HEVC, Rec. ITU‑T H.273 / ISO/IEC 23091‑2).
Practical applications and who should use it
- Tool and codec developers: Implementers of encoders/decoders, metadata generators and LUTs will use the report to map CICP values correctly and prevent mismatches (e.g., PQ values paired with incompatible primaries).
- Post-production and color grading engineers: Ensures correct representation and preservation of creative intent via mastering display and transfer metadata.
- Broadcasters & OTT platforms: Use guidance to carry and interpret video signal type metadata across ingest, contribution, and distribution chains.
- Device manufacturers and systems integrators: Apply carriage and interface guidance for reliable end-to-end workflows across SDI, file-based, and streaming systems.
Related standards
- ISO/IEC 23091-2 / Rec. ITU‑T H.273 - Coding-independent code points (CICP) for video
- Rec. ITU‑T H.264 | ISO/IEC 14496-10 (AVC)
- Rec. ITU‑T H.265 | ISO/IEC 23008-2 (HEVC)
- SMPTE metadata and carriage specs referenced where applicable
This report is essential reading for anyone implementing or operating modern video production and distribution chains who needs accurate, interoperable metadata handling for SDR/HDR and wide/narrow colour workflows.