Why it matters

HLS is the widest-supported video streaming protocol. Understanding it enables broad reach.

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The architecture

Segments: .ts (MPEG-TS) or .m4s (fMP4). Typically 2-10 seconds each.

Media playlist (.m3u8): list of segments with durations.

Master playlist: lists media playlists at different bitrates for adaptive.

HLS structureSegments2-10 sec chunksMedia playlist.m3u8Master playlistadaptive bitratesAdaptive bitrate: client picks bitrate based on bandwidth, switches on demand
HLS layers.
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How it works end to end

Adaptive bitrate (ABR): client measures throughput, picks best bitrate. Switches on segment boundaries.

Live vs VOD: live has rolling manifest; VOD has fixed manifest.

Low-Latency HLS: partial segments enable ~1s latency.

Encryption: AES-128 supported natively.