HTTP Live Streaming (HLS)
HLS is the dominant streaming format for live and VOD on Apple devices, CDNs, and most broadcast workflows. M3U8 text manifest + segmented media is the canonical chunked-file envelope pattern.
What It Defines
Adaptive bitrate streaming protocol: M3U8 playlist manifest (master + media playlists) referencing MPEG-TS or fMP4/CMAF segments. Tags (`#EXT-X-VERSION`, `#EXTINF`, `#EXT-X-KEY` for AES-128 encryption) define stream structure. MIME types: `application/vnd.apple.mpegurl`, `application/x-mpegURL`.
Canonical (Normative)
Convenient (Practical)
The canonical publication point for finalized RFCs. If a protocol is standardized as an RFC, the RFC Editor text is the normative final reference. Published by the IETF, IRTF, IAB, and independent stream.
Related Specs
DASH is the open-standard counterpart to HLS for adaptive video. MPD manifest structure + fMP4 segment layout is how Netflix-style streaming works outside the Apple ecosystem.
MP4 is the dominant video container on the web and in MSE players. Box hierarchy, codec vs container distinction, and fragmenting (fMP4 for HLS/DASH) are essential for media engineering.
Video players (YouTube, Netflix, Twitch) use MSE for adaptive streaming. Required if you build a custom media player or do in-browser video processing.
AAC is the default audio codec for YouTube, Apple ecosystems, and most HLS/DASH streams. Distinguish ADTS-framed AAC from AAC inside MP4 boxes.
H.264 remains the most widely supported video codec. Distinguish codec (H.264 bitstream) from container (MP4/WebM) when debugging playback, transcoding, and MSE SourceBuffer codec strings.
HLS historically delivered MPEG-TS segments — still common in broadcast IPTV and legacy VoD. TS packet structure explains why HLS segment boundaries differ from fMP4 CMAF.