ISO/IEC 23009-8:2025

Overview

ISO/IEC 23009-8:2025 - "Information technology - Dynamic adaptive streaming over HTTP (DASH) - Part 8: Session-based DASH operations" defines how to attach session-specific data to MPEG‑DASH streaming sessions without creating unique per-session MPDs. It specifies the Session‑Based Description (SBD) document format and the MPD extension used to reference SBDs, enabling clients to derive session parameters that are appended to segment URLs (for example, as query parameters). The second edition updates include URL customization and other extensions.

Key topics and technical requirements

• SBD format and semantics: Defines a sidecar Session‑Based Description that maps time ranges on the DASH timeline to keyed values (timed key‑value pairs). Includes both XML (MPD extension) and JSON elements (SBD document content) and a KeyValue object schema.
• MPD signalling for SBD: Specifies how to reference an SBD from the Media Presentation Description (MPD) so a cached MPD can be reused while session‑specific parameters are applied at runtime.
• Timeline and orderline addressing: Mechanisms for mapping SBD entries to timeline segments or orderlines so the correct parameters apply to each requested segment.
• Client processing model: Normative requirements for an SBD client include parsing SBD, building a timeline/orderline table, deriving parameter values for a request time, and appending queries to HTTP GET segment requests.
• Standards conformance and syntax: Relies on ISO/IEC 23009‑1 (MPEG‑DASH MPD/segment format), RFC 3986 (URI syntax) and RFC 8259 (JSON). Annexes include the SBD MIME type.
• Session metadata: Concepts such as SBDStart (session start time), session parameters, and sidecar document usage are standardized.

Applications and who should use it

• Streaming platform engineers and CDN operators: Apply session parameters without issuing unique per‑session MPDs, preserving cache efficiency while enabling per‑session customization.
• Player/client developers: Implement the SBD client logic to parse SBDs, compute per‑segment query parameters, and perform segment requests accordingly.
• Use cases:
  • Forensic watermarking and content tracing (explicit example in the standard)
  • Personalization and targeted ad selection where parameterized segment requests are required
  • Session‑level analytics and A/B testing without proliferating MPDs
• Standards architects and test labs: Validate interoperability of MPD extensions and SBD document compliance.

Related standards

• ISO/IEC 23009-1 (MPEG‑DASH MPD and segment formats)
• IETF RFC 3986 (URI: Generic Syntax)
• IETF RFC 8259 (JSON Data Interchange Format)

Keywords: ISO/IEC 23009-8:2025, MPEG‑DASH, DASH, session‑based description, SBD, MPD extension, adaptive streaming, streaming session, CDN, forensic watermarking.