HTTP Live Streaming (also known as HLS) is an HTTP-based media streaming communications protocol implemented by Apple Inc. as part of their QuickTime and iOS software. 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 a result, a client media player (such as iTVmediaPlayer or VLC Media Player) can begin playing the data (such as a movie) before the entire file has been transmitted. 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, it downloads an extended M3U (m3u8) playlist containing the metadata for the various sub-streams which are available.[1]
Since its requests use only standard HTTP transactions, HTTP Live Streaming is capable of traversing any firewall or proxy server that lets through standard HTTP traffic, unlike UDP-based protocols such as RTP. This also allows content to be delivered over widely available CDNs.
HLS also specifies a standard encryption mechanism[2] 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 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 devices together with a sequential initialization Vector for each chunk to their implementation of the standard.[3]
Apple has documented HTTP Live Streaming as an Internet Draft (Individual Submission), the first stage in the process of submitting it to the IETF as an Informational Request for Comments. However, while Apple has submitted occasional minor updates to the draft, no additional steps appear to have been taken towards IETF standardization.[4]
Contents [hide]
1 Server implementations
2 Usage
3 Supported players and servers
3.1 Clients
3.2 Servers
4 See also
5 References
6 External links
Server implementations[edit]
Adobe Media Server supports HLS for iOS devices (HLS) and Protected HTTP Live Streaming (PHLS).
Akamai supports HLS for live and on-demand streams.
Cisco Systems: Supports full end to end delivery for Live/TSTV/VOD and Cloud DVR services.
EdgeCast Networks supports cross-device streaming using HLS.
Helix Universal Server from RealNetworks supports iPhone OS 3.0 and later for live and on-demand HTTP Live or On-Demand streaming of H.264 and AAC content to iPhone, iPad and iPod.
IIS Media Services from Microsoft supports live and on-demand Smooth Streaming and HTTP Live Streaming.
InstaTV Server supports HTTP Live Streaming of ATSC/ClearQAM HDTV from Windows PC with any TV tuner card to iPhone, iPod, and iPad.
Level 3 supports HLS live and on-demand streams.
Limelight Networks supports HLS for some accounts.[5]
Mistserver supports HLS in live, on-demand and live replay mode
Nginx with the RTMP Module supports HLS in live mode.
TVersity supports HLS in conjunction with on-the-fly transcoding for playback of any video content on iOS devices.
Unreal Media Server supports low latency HLS as of version 9.5.
VBrick Distributed Media Engine supports HLS for serving live and on-demand HLS.
VLC Media Player supports HLS for serving live and on-demand streams as of version 2.0[6]
VODOBOX Live Server supports HLS for iPhone, iPad, iPod, Google Android devices (Honeycomb 3.0 and above) and Adobe Flash Player with HLS plugin.
Wowza Media Server from Wowza Media Systems supports HLS for live and on-demand streaming.
Usage[edit]
Adobe Systems demonstrated an update to its Adobe Flash Media Server product supporting HTTP Live Streaming at the NAB Show in April 2011
Apple Inc. used this on September 1, 2010 to stream their iPod Keynote event live over the internet, and on October 20, 2010 to stream their 'Back to the Mac' Keynote event live over the internet.
Google added HTTP Live Streaming support in Android Honeycomb and later.[7]
Helix Universal Server from RealNetworks supports iPhone OS 3.0 and later for live and on-demand HTTP Live or On-Demand streaming of H.264 and AAC content to iPhone, iPad and iPod initial release April 2010, latest release November 2012
HLSProvider provides HTTP Live Streaming support for Chromeless Flash Player, JWPlayer, and OSMF 2.0 since May 2013 [8]
HP added HTTP Live Streaming support in webOS 3.0.5.[9]
Livestation streams numerous TV channels such as France 24, RT, and Al Jazeera English.[1]
Microsoft added support for HTTP Live Streaming in IIS Media Services 4.0.[10]
Flussonic added HTTP Live Streaming and Video On Demand support in January 21, 2009.
Onlinelib added HTTP Live Streaming support in HLS Player and SDK for flash version 2.0, Plugin for JW-Player, OSMF 2.0 and Adobe Strobe Media Playback[11]
Wowza Media Systems released Wowza Media Server 2.0 with full support for HTTP Live Streaming on December 9, 2009[12]
Yospace added HTTP Live Streaming support in Yospace HLS Player and SDK for flash version 1.0[13]
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