Overview
ISO/IEC 21122-3:2024 specifies transport and container formats for JPEG XS codestreams (as defined in ISO/IEC 21122-1). It defines file formats and embedding rules for working with still images (JXS) and motion image sequences on computer platforms, and gives guidance for embedding JPEG XS codestreams in transport streams for internet-based communication. The third edition adds support for temporal differential coding (TDC) and clarifies handling of interlaced signals.
Key topics and requirements
- Container and transport definitions
- Specifies how to wrap JPEG XS codestreams in file containers and transport streams using box/superbox structures.
- Extends existing file-format specifications to support embedding of JPEG XS codestreams.
- File formats
- Normative guidance for a JXS still-image file format (Annex B).
- Integration into ISO Base Media File Format (ISOBMFF) for motion sequences (Annex C).
- Integration into HEIF for combined still and motion workflows (Annex D).
- Metadata and signalling
- Defines metadata boxes to signal colourspace, timing, presentation and other image properties; ensures proper interpretation and presentation.
- Uses coding-independent code points (CICP) and references Rec. ITU‑T H.273 / ISO/IEC 23091-2 for colour specification.
- Transport and internet use
- Guidance on embedding codestreams in transport streams to enable low-latency internet communication and editing workflows.
- Conformance rules
- Readers must ignore unrecognized boxes; Annex A provides the common syntax elements and box definitions used throughout.
- Practical performance targets
- Addresses JPEG XS use cases where low latency and robustness under multiple recompression cycles matter; typical visually lossless compression ratios ~2:1 to 20:1 and end-to-end latency can be a fraction of a frame.
Applications
- Live production and broadcast workflows requiring low-latency, low-complexity image transport.
- Real-time video contribution, remote production, and editing systems where recompression robustness and minimal latency are critical.
- File-based storage and interchange of JPEG XS stills and movies in media asset management, archiving, and cloud workflows.
- Web and internet streaming scenarios needing efficient embedding of JPEG XS in transport streams.
Who should use this standard
- Systems integrators, codec implementers, and software developers building JPEG XS encoders/decoders and muxers.
- Broadcast engineers, live-production vendors, media-asset managers, and OTT platform architects.
- Standards and compliance teams ensuring interoperability of JPEG XS media files and transport streams.
Related standards
Keywords: JPEG XS, low-latency, transport and container formats, JXS, ISOBMFF, HEIF, codestream, metadata, temporal differential coding, interlaced signals.