HTTP Live Streaming
| Filename extension | .m3u8 |
|---|---|
| Internet media type | application/vnd.apple.mpegurl |
| Developed by | Apple Inc. |
| Initial release | May 2009 |
| Extended from | extended M3U |
HTTP Live Streaming (also known as HLS) is an HTTP-based media streaming communications protocol implemented by Apple Inc. as part of its QuickTime, Safari, OS X, and iOS software. It resembles MPEG-DASH in that it works by breaking the overall stream into a sequence of small HTTP-based file downloads, each download loading one short chunk of an overall potentially unbounded transport stream. As the stream is played, the client may select from a number of different alternate streams containing the same material encoded at a variety of data rates, allowing the streaming session to adapt to the available data rate. At the start of the streaming session, HLS downloads an extended M3U playlist containing the metadata for the various sub-streams which are available.
Since its requests use only standard HTTP transactions, HTTP Live Streaming can traverse any firewall or proxy server that lets through standard HTTP traffic, unlike UDP-based protocols such as . This also allows content to be offered from conventional HTTP servers as origin and delivered over widely available HTTP-based content delivery networks.
HLS also specifies a standard encryption mechanism using AES and a method of secure-key distribution using HTTPS with either a device-specific realm login or HTTP cookie which together provide a simple DRM system. Later versions of the protocol also provide for trick-mode fast-forward and rewind and for integration of subtitles. upLynk has also added the AES scrambling and base-64 encoding of the DRM content-key with a 128-bit device-specific key for registered commercial SWF applications together with a sequential initialization Vector for each chunk to its implementation of the standard.
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