ISO/IEC 23009-8:2022

Overview

ISO/IEC 23009-8:2022 defines session-based operations for Dynamic Adaptive Streaming over HTTP (DASH). The standard specifies the format of the Session-Based Description (SBD) sidecar document and the MPD extension needed to reference and use SBD data with MPEG-DASH (ISO/IEC 23009-1). Its purpose is to enable session-specific values (timed key‑value pairs) to be applied to segment requests without creating per-session MPDs - enabling client-driven, session-aware customization of segment URLs in standard HTTP GET requests.

Key topics and technical requirements

• SBD data model: SBD is a timed key-value store (session-based description) where each entry maps a timeline time range to one or more parameter strings. The document includes semantics for the SBD timeline and how values are applied across time ranges.
• MPD signalling and extension: The MPD is extended to reference an external SBD document (URL). The MPD signalling describes how clients discover and fetch the SBD.
• SBD descriptor and schemas: XML schema for the MPD extension (SBD descriptor) and JSON schema for SBD objects (e.g., KeyValue objects) are provided to ensure interoperable encoding and parsing.
• Client operation requirements: Normative requirements for a session-based DASH client include parsing the SBD, building timeline/orderline tables, deriving parameter values, and adding parameters to HTTP segment requests.
• Timeline and orderline addressing: The standard defines how SBD time ranges align to DASH timelines and segment addressing (e.g., per-segment query parameters).
• MIME type and interoperability: The document includes SBD MIME type guidance and references for related formats and protocols (HTTP, URI, JSON).

Practical applications

• Session-aware personalization: Add per-session parameters (e.g., user, quality hints) to segment requests without per-session MPDs.
• Analytics and tracking: Include session metadata in segment URL query strings for analytics pipelines and CDN logging.
• Forensic watermarking: Apply session-specific watermarking parameters or identifiers to requested segments to enable traceability (explicit example in the standard).
• Integration with CDNs and caches: Keep MPDs cacheable on CDNs while attaching session-specific data via a separate SBD sidecar.

Who should use this standard

• Streaming platform architects and engineers
• DASH client and player developers
• CDN and delivery engineers
• Forensic watermarking and analytics solution providers
• Standards implementers and interoperability test teams

Related standards

• ISO/IEC 23009-1 (DASH MPD and segment formats)
• ISO/IEC 14496-12 (ISO-BMFF)
• IETF RFC 7230 (HTTP/1.1), RFC 3986 (URI syntax), RFC 8259 (JSON)

Keywords: ISO/IEC 23009-8:2022, DASH, Session-Based Description, SBD, MPD extension, adaptive streaming, session parameters, forensic watermarking.