Overview - ISO/IEC 23009-6:2017 (DASH with server push and WebSockets)
ISO/IEC 23009-6:2017 extends MPEG‑DASH (Dynamic Adaptive Streaming over HTTP) to take advantage of full‑duplex HTTP‑compatible protocols - notably HTTP/2 and WebSocket. The standard specifies how to carry DASH media presentations using server push and bi‑directional messaging to optimize delivery performance (for example, reducing latency for live streaming) while maintaining fallback compatibility with HTTP/1.1.
Key topics and technical requirements
- Carriage over full‑duplex protocols: Defines bindings and message formats to carry DASH over HTTP/2 (Clause 7) and WebSocket (Clause 8).
- Signalling and message formats: Specifies the signalling primitives and JSON/ABNF style data types used to coordinate delivery (e.g., PushDirective, PushAck, URLList, URLTemplate, FastStartParams).
- Push strategies: Introduces configurable push strategies that let a client express expectations and the server acknowledge how segments will be pushed (server‑initiated vs. client‑initiated delivery).
- MPD and segment flow: Covers MPD requests, segment requests, pushed segment messages, acknowledgements, cancel messages and end‑of‑stream semantics for both transport bindings.
- Protocol upgrade and fallback: Describes mechanisms for establishing media channels (including HTTP protocol upgrade) and graceful fallback to HTTP/1.1 when HTTP/2/WebSocket are unavailable (informative annexes).
- Informative examples: Includes practical examples of HTTP/2 and WebSocket client/server behaviour, URL templates, fast start procedures and system architecture (Annexes B–H).
Applications and practical benefits
- Low‑latency live streaming: Server push and WebSocket reduce round trips and enable faster delivery of initialization and segment data for live events.
- Efficient multiplexing: HTTP/2 stream multiplexing and WebSocket frames allow concurrent, prioritized delivery of MPD and media segments.
- Adaptive bitrate OTT delivery: Improves responsiveness for adaptive switching and fast start‑up, benefiting OTT services and live TV.
- CDN and origin server optimization: Enables smarter server‑side delivery strategies (pre‑push, cancelation, prioritized pushes) to reduce buffering and wasted bandwidth.
Who should use this standard
- Streaming engineers and protocol implementers
- Media server and CDN developers
- Browser and player vendors implementing DASH clients
- OTT architects focused on low‑latency live and adaptive streaming
- Standards and interoperability test teams
Related standards
- ISO/IEC 23009‑1 - MPEG‑DASH (core MPD and segment model)
- IETF RFC 6455 - WebSocket protocol
- IETF HTTP/2 (IETF specification) and RFC 7231 - HTTP semantics
ISO/IEC 23009‑6:2017 is essential when implementing DASH delivery that leverages HTTP/2 server push and WebSocket messaging to improve latency, control and resource efficiency in modern streaming systems.
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