LowLatencyDASH

Low Latency DASH (LL-DASH) is an extension of the MPEG-DASH streaming standard aimed at reducing end-to-end latency for live and near-live content delivered over HTTP. By enabling faster delivery of media segments and more timely signaling, LL-DASH seeks to bring the live edge within a few seconds of real time in suitable networks and devices.

Technical foundations: LL-DASH builds on ISO/IEC 23009-6 and CMAF-based fMP4 segments. It introduces signaling and segment structures that allow clients to begin playback using very small, near-real-time segments (often 1–2 seconds) and to fetch only the parts of a segment that are necessary. The Media Presentation Description may include availabilityStartTime, segment timelines, and timing offsets to facilitate low-latency delivery. HTTP range requests and CMAF chunking are used to retrieve partial segments; clients can prefetch adjacent segments to shorten startup and rebuffer times.

Low-latency techniques: Partial segments, shorter segment durations, and improved buffering strategies, plus prefetching and rapid adaptation across representations. The approach remains compatible with standard DASH playback and existing CDNs when CMAF is used.

Adoption and ecosystem: LL-DASH is standardized within MPEG-DASH and has been implemented in several popular players and tooling, including dash.js and Shaka Player, and in many live streaming pipelines that use CMAF. It is used by broadcasters and streaming platforms to reduce latency in live events.

Limitations: Achieving consistent low latency depends on network conditions, encoder/segment generation rates, and client capability. Not all deployments achieve sub-second latency; latency can vary with live window management and segment configuration.