HTTP Live Streaming

HTTP Live Streaming playlist

Filename extension	.m3u8
Internet media type	application/vnd.apple.mpegurl
Developed by	Apple Inc.
Initial release	May 2009
Type of format	Playlist
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 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, it downloads an extended M3U playlist containing the metadata for the various sub-streams which are available.

HLS Live Stream Example

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 offered from conventional HTTP servers as origin and delivered over widely available HTTP-based CDNs.

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 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.

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.

Architecture

HTTP Live Streaming uses a conventional web server to distribute audiovisual content and requires specific software to fit into the proper format transmission in real time. The service architecture comprises:

Server

Codify and encapsulate the input video flow in a proper format for the delivery. Then, it is prepared for distribution by segmenting it into different files. In the process of intake, the video is coded and segmented to generate video fragments and index file.

• Encoder: codify video files in H.264 format and audio in MP3, HE-AAC or AC-3. This is encapsulated by MPEG-2 Transport Stream to carry it
• Segmenter: divides the MPEG-2 TS file into fragments of equal length, kept as .ts files. It also creates an index file that contains references of the fragmented files, saved as .m3u8

Distributor

Formed by standard web Server, accepts requests from clients and delivery all the resources needed for streaming.

Client

Demand and download all the files and resources, assembling them so that they can be presented to the user as a continuous flow video. The client software downloads first the index file through a URL and then the several media files available. The playback software assembles the sequence to allow the continue display to the user.

Features

HTTP Live Streaming provides mechanisms to provide a scalable and adaptable to network, allowing playback quality in wireless networks with high bandwidth and low quality playback on 3G networks, where the bandwidth is reduced. HTTP Live Streaming also provides protection against errors, generating alternative different flows video to use them if there are any errors in segment.

Scalability

To make the system scalable and adaptable to the bandwidth of the network, the video flow is coded in different qualities. Thus, depending on the bandwidth and transfer network speed, the video will play at different qualities.

To implement this, the system must encode the video in different qualities and generate an index file that contains the locations of the different quality levels.

The client software internally manages the different qualities, making requests to the highest possible quality within the bandwidth of the network. Thus always play the video the highest possible quality, viewing lower quality on 3G networks and highest quality in Wi-Fi broadband.

One issue that can arise by relying on the client-side system is that a user may experience different bitrates throughout the duration of playback. This can be avoided by delaying the responsiveness of the player to changes in client-side bandwidth.

Protection against errors

Protection against errors works like scalability. In this case is generated a different flows with the same quality video and locations are listed in the index file.

The management of all files is done from the client, so that if it fails the first flow, use the next and successively.

HTTP Live Streaming also allows you to combine the protection of errors and scalability. In this case generates an index file that contains for each bandwidth the alternative flows of the videos.

Server implementations

• Adobe Media Server supports HLS for iOS devices (HLS) and Protected HTTP Live Streaming (PHLS).
• Akamai supports HLS for live and on-demand streams.
• Amazon CloudFront supports HLS for on-demand streams.
• bitmovin provides the cloud transcoding service bitcodin.com which supports HLS for on-demand and live streaming.
• Cisco Systems: Supports full end to end delivery for Live/TSTV/VOD/HLS and Cloud DVR services.
• EdgeCast Networks supports cross-device streaming using HLS.
• Edgeware: Supports full end to end delivery for Live/TSTV/VOD/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.
• Level 3 supports HLS live and on-demand streams.
• Limelight Networks supports HLS for some accounts.
• Nginx with the RTMP Module supports HLS in live mode.
• Nimble Streamer supports HLS in live and VOD 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.
• Ustream supports HLS delivery of live broadcasts. The ingested stream is re-transcoded if the original audio and video codec falls outside HLS requirements.
• VLC Media Player supports HLS for serving live and on-demand streams as of version 2.0
• Wowza Streaming Engine from Wowza Media Systems supports HLS and encrypted HLS for live (with DVR) and on-demand streaming.

Usage

• 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 itsiPod Keynote event live over the internet, and on October 20, 2010 to stream its 'Back to the Mac' Keynote event live over the internet.
• Google added HTTP Live Streaming support in Android Honeycomb and later.
• 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
• flashls is an open-source Adobe Flash/Adobe AIR plugin that provides HTTP Live Streaming support for Chromeless Flash/Air Player, Flowplayer, Video.js, mediaelement.js and Open Source Media Framework 2.0
• HP added HTTP Live Streaming support in webOS 3.0.5.
• Microsoft added support for HTTP Live Streaming in IIS Media Services 4.0.
• Yospace added HTTP Live Streaming support in Yospace HLS Player and SDK for flash version 1.0
• Sling Media added HTTP Live Streaming support to its Slingboxes and its SlingPlayer apps
• In 2014/15, the BBC introduced HLS-AAC streams for its live internet radio and on-demand audio services, and supports those streams with its iPlayer Radio clients.

Supported players and servers

Clients

Product	Platform	Live Streaming	DRM	As of Version	Vendor
Android (native media support)	Android	Yes	Yes	3.0+ Support for HLS streams in the stock browser or Chrome is generally stable from Android 4.1 onwards (with minor issues).	Google
iOS (native media support)	iOS	Yes	Yes	3.0+ Has full HLS support. HLS streams can be accessed via Safari without the need of any 3rd-party app.	Apple
Safari (web browser)	OS X, iOS	Yes	Yes	6.0+	Apple
Google Chrome (web browser)	Android, iOS	Yes	Yes	30+ Unsupported on desktop OSes	Google
Microsoft Edge (web browser)	Windows 10	Yes	Yes		Microsoft
QuickTime Player (media player)	OS X	Yes	Yes	10.0+	Apple
iTunes (music player)	Windows, OS X	Yes	Yes	10.1+ Has full HLS support. To play a HLS stream, go to File > Open Stream and replace "http://" with "itls://" in the stream URL.	Apple
VLC media player (media player)	Windows, OS X, Linux, Android, iOS, Windows Phone	Partial	No	2.0 Has partial HLS support. VLC may load the playlist as individual chunks instead of a gapless live stream for some server configurations. This causes a slight pause or missing audio between each file segment.	VideoLAN
Media Player Classic Home Cinema (media player)	Windows	No	Yes		Gabest, Doom9 forum users
PotPlayer (media player)	Windows	Yes	Yes		Daum Communications
MPlayer / SMPlayer / mpv (media player)	Windows, Linux	Yes	Yes		Ricardo Villalba
Audacious (software) (music player)	Windows, Linux	Yes	Yes
Radio Tray (radio player)	Linux	Yes	Yes		Carlos Ribeiro
Kodi (software) (home entertainment application)	Windows, OS X, Linux, Android, iOS	Yes	Partial	12.0 Alpha 5 and later DRM support requires a monthly/nightly build	XBMC Foundation
MythTV (home entertainment application)	Windows, OS X, Linux, FreeBSD	Yes	Yes	0.26	MythTV
JRiver Media Center (home entertainment application)	Windows, OS X	Yes	Yes		JRiver
XiiaLive (radio player)	Android, iOS	Yes	Yes	3.0+ Plays internet radio streams (audio only).	Visual Blasters LLC
Tunein radio (radio player)	Android, iOS	Yes	Yes	3.3+ Plays internet radio streams (audio only).	TuneIn
myTuner Radio (radio player)	Android, iOS, Windows Phone, Windows 8, OS X	Yes	Yes		Appgeneration Software
Internet Radio Player (radio player)	Android	Yes	Yes		MuserTech
GuguRadio (radio player)	iOS	Yes	Yes		Leon Fan
MX Player (media player)	Android, iOS	Yes	Yes		J2 Interactive
RockPlayer (media player)	Android, iOS	Yes	Yes		Shanghai ChangeTech Co. Ltd.
DicePlayer (media player)	Android 2.2+	Yes	Yes	Diceplayer 1.0+	INISOFT
HP Touchpad	WebOS	Yes	Yes	3.0.5	HP
Amino x4x STB	Amino set-top boxes	Yes	Yes	2.5.2 Aminet	Aminocom.com
Dune HD TV	Dune HD set-top boxes	Yes	Yes	TV Series	dunehd.com
nangu.TV	Motorola set-top boxes	Yes	Yes	2.0	nangu.TV
Roku Digital Video Player	Roku set-top boxes	Yes	Yes	Roku OS / SDK 2.6	Roku
Telebreeze Player (online service)	HTML, Android, iOS, Windows, MacOS, Roku STB, MAG250, Samsung SmartTV, LG SmartTV, T503, Enigma	Yes	Yes	3.2	Telebreeze
bitdash (SDK)	HTML5 or Flash, Web and Mobile	Yes	Yes	Version 3.0+	bitmovin
3ivx (SDK)	Windows 8, Windows Phone 8 & Xbox One	Yes	Yes	2.0	3ivx
THEOplayer (SDK)	HTML5	Yes	Partial		OpenTelly
Viblast Player (SDK)	HTML5, iOS, Android	Yes	Partial		Viblast Ltd
Flowplayer (SDK)	Adobe Flash, iOS, Android	Yes	Yes	The Flash HLS plugin is available from GitHub.	Flowplayer Ltd
JW Player (SDK)	Adobe Flash, iOS, Android	Yes	Yes	A Premium or Enterprise license is required for HLS support.	JW Player
Radiant Media Player (SDK)	Adobe Flash, HTML5	Yes	Yes	1.5.0	Radiant Media Player
Yospace (SDK)	Adobe Flash	Yes	Yes	2.1	Yospace
Onlinelib (SDK)	Adobe Flash	Yes	Yes	2.0	Onlinelib.de
VODOBOX HLS Player (online service)	Adobe Flash, HTML5, iOS, Android	Yes	Yes		Vodobox
NexPlayer (SDK)	iOS, Android, Windows Phone	Yes	Yes		NexStreaming
ffplay/avplay (multimedia framework)		Yes	Partial		FFmpeg/Libav
GPAC (multimedia framework)		Yes	No	0.5.0	Telecom ParisTech inc.

Servers

Product	Technology	As Of Version	Vendor	Notes
bitcodin		SaaS	bitmovin
VLC		1.2
Unicorn Once		SaaS	Unicorn Media
IIS Media Services		4.0	Microsoft
Antik Media Streamer	Ingest Module (UDP/HTTP Transport Stream, Backup Stream with auto-switching, stream status monitoring and logging), Stream replication UDP/HTTP, HLS streaming, Video archive with snapshots, Server-side Timeshift, Timezone Shifting with multi-timezones, Stream Encryption using AES and key-rotation (with Antik Key Server)	3.0	Antik technology
Adobe Media Server	Live and VOD streaming as origin and edge server	5.0	Adobe
Evostream Media Server	Cross-platform including embedded systems such as encoders, IP cameras, DVRs, and more. Supports: Adobe Flash RTMP, RTMPS, LiveFLV, full transcoder for creating lower bitrate streams, HTTP Live Streaming (HLS) for streaming to iPhones, iPads and Androids, HTTP Dynamic Streaming (HDS) for Adobe Air, Microsoft Smooth Streaming (MSS) for Microsoft devices, RTSP with RTP or MPEG-TS, MPEG-TS (unicast/multicast), compatible Live Encoding, strong security for your content ( Verimatrix DRM, HLS AES encryption, Stream Aliasing, Watermarking), built-in clustering mechanism and more.	1.6.5	EvoStream
MythTV		0.25	MythTV
MACNETIX VOD-Server		3.0	MACNETIX
Anevia ViaMotion Servers	Transcapsulation: from one input, several outputs (HLS, MS Smooth Streaming, ADS Flash, MPEG DASH)		Anevia
Packet Ship OverView:Origin Server	Capture from IPTV multicast and chunking to HLS for multi-bandwidth live streams, with AES encryption	2.1	Packet Ship
nangu.TV Streamers	on-the-fly adaptation: content is stored once enabling several outputs (HLS, MS Smooth Streaming, ADS Flash, MPEG DASH)		nangu.TV
TVersity Media Server		1.9	TVersity	Pro Edition only
Helix Universal Server	Live + VOD HLS with Verimatrix DRM integration, ABR, Multi-Resolution, AES encryption	15.0+	RealNetworks	High performance HLS (12,000+ concurrent devices)
Wowza Streaming Engine	Live and VOD streaming as origin and edge server with DVR, DRM Integration and Transcoding for adaptive delivery. Outputs to MPEG-DASH, HLS, HDS, Smooth Streaming, RTMP, and RTSP	2.0+	Wowza Media Systems
Unified Streaming Platform	Muxes media content from one unified source to multiple outputs (Smooth Streaming, HDS, HLS and MPEG DASH)		Unified Streaming
VODOBOX Live Server	Outputs HTTP Live Streaming with Adaptive Bitrate (up to 6 simultaneous qualities). Video codecs : AVC H.264 / HEVC H.265 Audio codecs : MP3 / AAC Transport layers : HTTP / FTP / Amazon AWS S3 / Microsoft Azure Web Storage / writing to disk (NetBios / Samba) Hostings : internal HTTP Web server and/or external Web servers (ex: Apache, IIS, NGinx, etc.)	1.0	Vodobox	Supports input live streams from DVB-T devices, satellite receivers (Dreambox), IP streams (RTSP, RTMP, MMS, HTTP), Microsoft DirectShow drivers (video capture cards, live production software, camera).
Flixwagon Platform Video Server			Flixwagon
StreamCoder Live Encoder	Realtime video encoder (inputs : DVB/IP stream or video signal). Supports multi-bitrates and multi-languages		Ektacom
Apache HTTP Server			Apache Software Foundation
Unreal Media Server		9.5	Unreal Streaming Technologies	Latency of live streams can be as low as 2.5 seconds over the Internet
lighttpd		1.4.x
Nimble Streamer	RTMP / RTSP / Icecast / MPEG-TS to ABR HLS. MP4 / MP3 to VOD HLS	1.0.0-x	WMSPanel
Nginx-rtmp-module	Free module for nginx server with support of HLS live streaming. Compliant with iOS and Android.	0.9.x	Roman Arutyunyan
Nginx Plus	VOD HLS as origin		NGINX, Inc.
Flussonic Media Server	Multi-platform support for HTTP, RTSP, RTMP, Time Shifting, DVR Functions with Unlimited Rewind Capabilities HLS streaming specific to iOS platform support.	3.0+	Flussonic, LLC.	Supporting a magnitude of features with full HTTP support.
VBrick Distributed Media Engine ("DME")		2.0	VBrick Systems, Inc.	Live and stored HLS. Live can be transmuxed from several input mux including RTP, RTMP, and MPEG-TS using H.264 encoding
Telebreeze Coder / Media Server	HLS, HTTP TS, TimeShift, VoD, DVR, Hardware Acceleration	2.0	Telebreeze
Media Streaming Server SDK	Converts files on the fly to Flash, Adobe HDS, Apple HLS, MPEG-DASH, Microsoft Smooth Streaming, RTSP and HTML5.	19.0	LEAD Technologies

VOD encoders

Product	Technology	As Of Version	Vendor	Notes
VODOBOX HLS Encoder	Converts video files into pre-encoded HLS Adaptive Bitrate streams, ready to be hosted and streamed by Apache/IIS Web servers/NGinx. Supports AVC H.264 / HEVC H.265.	1.0	Vodobox	Transcode classic video files (avi, mp4, m2ts, ...) into HLS streams with multi-qualities for VOD or replay usage.

See also

• Adaptive bitrate streaming