LL-HLS (Low-Latency HLS) is Apple's standardized extension that brings HLS live latency down from 20-30 seconds to roughly 2-5. It works by publishing partial segments (small chunks of a segment) before the full segment is ready, plus playlist hints and blocking requests so the player gets new media almost as soon as it exists.
Because it stays within the HLS ecosystem, LL-HLS plays on Apple devices natively and reuses ordinary CDN infrastructure, though the CDN must support the required HTTP behaviors. The trade-off is the universal one for low latency: smaller buffers leave less cushion for network jitter, so resilience tuning matters more.
