LL-DASH attacks the same latency problem as LL-HLS but with DASH's tools. Instead of partial segments and preload hints, LL-DASH relies on CMAF chunks delivered via HTTP/1.1 chunked transfer encoding. The packager produces 200–400 ms CMAF chunks inside larger 2–4 s segments and streams them out the moment they exist. The MPD manifest carries an availabilityTimeOffset (ATO) attribute that tells the player to start requesting segments before their nominal availability time — the player relies on the in-progress chunked response to fill in the rest.
Player behaviour for LL-DASH is essentially "request the next segment as soon as the live edge moves, treat the chunked response as a stream of CMAF chunks, parse and inject each chunk into MSE as it arrives". dash.js has supported LL-DASH since 3.0 (2020); Shaka added support in 3.2 (2021). The 2024 IOP refinement added clearer guidance on suggested presentation delay, target latency and ABR behaviour under low-latency conditions.
LL-DASH and LL-HLS reach similar latencies and have similar CDN requirements (chunked transfer support, coalesced fetches, prefetching of partial responses). The choice between them is mostly platform-driven: Apple devices want HLS, everything else can play DASH. Most operators ship both from the same CMAF packager output, so the same chunks serve LL-HLS and LL-DASH simultaneously.
The book · Volume 2 of 7
Video Streaming: A Complete Guide to Video Delivery: From Network Protocols and Transport to Ingest, HLS, and MPEG-DASH
LL-DASH only reaches 2–5 seconds when the packager, the MPD timing and the CDN all pass CMAF chunks through without buffering them. This volume covers LL-DASH in detail alongside the glass-to-glass latency budget, CMAF chunked packaging, MPEG-DASH manifests and how HTTP delivery behaves under live load. Written by Nikolay Sapunov, CEO at Fora Soft.
Moving your live DASH channel to LL-DASH without stalls at the live edge?
Send us your packager and CDN setup and we will return an LL-DASH latency budget with chunk sizes, availabilityTimeOffset values and the CDN settings that keep chunks flowing. 250+ video products shipped since 2005.
