HTTP Live Streaming works by separating the overall stream (also referred as '.m3u8') into a sequence of small 10-second segments (.ts), adapting to the available bandwidth as the video plays. HTTP Live Streaming is capable of traversing any firewall or proxy server that lets through standard HTTP traffic. HTTP protocol joins the merits of RTMP/RTSP Streaming in terms of bandwidth efficiency, quality switching.
HTTP Live Streaming consists of three parts: the server component, the distribution component, and the client software.
1. The server component is responsible for taking input streams of media and encoding them digitally, encapsulating them in a format suitable for delivery, and preparing the encapsulated media for distribution.
2. The distribution component consists of standard web servers. They are responsible for accepting client requests and delivering prepared media and associated resources to the client. For large-scale distribution, edge networks or other content delivery networks can also be used.
3. The client software is responsible for determining the appropriate media to request, downloading those resources, and then reassembling them so that the media can be presented to the user in a continuous stream. Client software is included on iOS 3.0 and later and computers with Safari 4.0 or later installed.
In a typical configuration, a hardware encoder takes audio-video input, encodes it as H.264 video and AAC audio, and outputs it in an MPEG-2 Transport Stream, which is then broken into a series of short media files by a software stream segmenter. These files are placed on a web server. The segmenter also creates and maintains an index file containing a list of the media files. The URL of the index file is published on the web server. Client software reads the index, then requests the listed media files in order and displays them without any pauses or gaps between segments.
Benefits:
1. Cost Savings
HLS saves the video publisher and the receiving viewer’s data plan money.
HLS is a true video stream, which means it only delivers a few segments of video as it plays. For example, if a viewer watched five minutes of streamed video, their data plan is only dinged for five minutes of data consumption. In contrast, a progressive download of a video could result in only five minutes of actual view time, but 20 minutes of downloaded video passed to their iPhone.
2. Security
The HLS specification has provisions to ensure security of the stream, which is great news for broadcasters or publishers who want to stream licensed content. The entire HLS streams can be encrypted using AES-128; you can even encrypt each rendition or even a group of segments using unique keys.
3. Live Streaming
Another big advantage of HLS is you can stream live video content to iOS devices. Streaming live video to tablet devices like the iPad is very compelling. The iPad is basically a personal TV that you can take anywhere. The tablet as a TV is an idea that’s not lost on the major broadcasters and cable companies.
4. Real-Time In-Stream Ad Delivery
Last, but certainly not least, is how HLS provides the publisher with a unique opportunity when it comes to in-stream ad insertion.
Recall how HLS is a stream of ten-second segments of video; those segments can be created in such a way that a video ad can be injected into the content stream so that it plays out seamlessly for the viewer. The viewing experience is basically identical to watching a commercial on broadcast TV.
5. Android and Other Streaming Players supports HLS now
Android 3.0, Google’s new Mobile OS is now capable of playing HLS video.
HLS is no longer a just a Mobile Video Play. A lot of other streaming players also now support HLS. Several major publishers such as ABC, HULU are taking advantage of HLS in their iPad apps.
