Overview
ISO/IEC 23001-14:2019, "Information technology - MPEG systems technologies - Part 14: Partial file format," defines a generic, object‑oriented file format for describing files that have been partially received over lossy communication channels. The standard specifies how to encapsulate correctly received data, identify missing or corrupted blocks, and store repair metadata (for example, source locations or high‑level indexing information). It is designed to work with any file format and includes helper tools specifically for files derived from the ISO Base Media File Format (ISO/IEC 14496‑12).
Key topics and requirements
- Partial file structure: Files are composed of a header followed by one or more partial segments, all structured as ISO/IEC 14496‑12 style “boxes”.
- FileTypeBox branding: Partial files use compatible brands such as 'paff' (partial files) and 'pmff' (mixed partial files).
- Segment contents: Each partial segment contains received bytes, a byte‑map of valid ranges (relative to the segment), and optional repair information or source references.
- Box taxonomy: The standard defines mandatory and optional top‑level and segment‑level boxes (examples include PartialFileBox, PartialSegmentBox, PartialSegmentHeaderBox, PartialDataBox, PartialSegmentLocationBox, Source URL box, and helpers such as BoxFileIndexBox, BoxIndexBox, and DataIntegrityHashBox).
- Design considerations: The format supports continuous recording, resynchronization after byte losses, redistribution (local gateways), and out‑of‑band repair workflows.
- Metadata and integrity: It enables storage of reception metadata, repair pointers (e.g., source URL or offsets), and data integrity helpers for ISO/IEC 14496‑12 derived content.
- MIME registration: Annex A defines the associated MIME type for files conforming to the specification.
Practical applications and target users
- Content delivery and streaming engineers who need to record or exchange partially received media over unreliable networks.
- Software implementers building file repair tools, playback engines tolerant of missing bytes, or local gateway services that repackage and forward partially received files.
- Broadcasters and multicast distributors using lossy transports (e.g., FLUTE) who require documented loss traces and repair pointers.
- Archival and forensic use cases where documenting which bytes were received and which were lost is essential.
- Developers working with ISO Base Media File Format content who benefit from the standard’s helper tools (indexing and integrity).
Related standards
- ISO/IEC 14496‑12 (ISO Base Media File Format) - foundational box/object model used by this partial file format.
- Normative references include IETF RFC 5905 (NTP Version 4) for timing considerations.
Keywords: ISO/IEC 23001-14:2019, partial file format, MPEG systems, partial segments, FileTypeBox, paff, pmff, ISO/IEC 14496-12, file repair, lossy channels, data integrity.
