README.md



video.js HLS Tech

A video.js tech that plays HLS video on platforms that don't support it but have Flash.


Getting Started

Download the Media Source plugin as well as the HLS tech. On your web page:

<script src="video.js"></script>
<script src="videojs-media-sources.js"></script>
<script src="videojs-hls.min.js"></script>
<script>
  var player = videojs('test-vid', {
    techOrder: ['html5', 'hls', 'flash']
  }, function() {
    this.play();
  });
</script>


Documentation

HTTP Live Streaming (HLS) has
become a de-facto standard for streaming video on mobile devices
thanks to its native support on iOS and Android. There are a number of
reasons independent of platform to recommend the format, though:


Supports (client-driven) adaptive bitrate selection
Delivered over standard HTTP ports
Simple, text-based manifest format
No proprietary streaming servers required


Unfortunately, all the major desktop browsers except for Safari are
missing HLS support. That leaves web developers in the unfortunate
position of having to maintain alternate renditions of the same video
and potentially having to forego HTML-based video entirely to provide
the best desktop viewing experience.

This tech attempts to address that situation by providing a polyfill
for HLS on browsers that have Flash support. You can deploy a single
HLS stream, code against the regular HTML5 video APIs, and create a
fast, high-quality video experience across all the big web device
categories.

The videojs-hls tech is still working towards a 1.0 release so it
may not fit your requirements today. Specifically, there is no
support for:


Alternate audio and video tracks
Subtitles
Segment codecs other than H.264 with AAC audio
Internet Explorer < 10


Options

You may pass in an options object to the hls tech at player
initialization. You can pass in options just like you would for any
other tech:

videojs(video, {
  techOrder: ['hls'],
  hls: {
    withCredentials: true
  }
});


withCredentials

Type: boolean

When the withCredentials property is set to true, all XHR requests for
manifests and segments would have withCredentials set to true as well. This
enables storing and passing cookies from the server that the manifests and
segments live on. This has some implications on CORS because when set, the
Access-Control-Allow-Origin header cannot be set to *, also, the response
headers require the addition of Access-Control-Allow-Credentials header which
is set to true.
See html5rocks's article
for more info.


Runtime Properties


player.hls.playlists.master

Type: object

An object representing the parsed master playlist. If a media playlist
is loaded directly, a master playlist with only one entry will be
created.


player.hls.playlists.media

Type: function

A function that can be used to retrieve or modify the currently active
media playlist. The active media playlist is referred to when
additional video data needs to be downloaded. Calling this function
with no arguments returns the parsed playlist object for the active
media playlist. Calling this function with a playlist object from the
master playlist or a URI string as specified in the master playlist
will kick off an asynchronous load of the specified media
playlist. Once it has been retreived, it will become the active media
playlist.


player.hls.mediaIndex

Type: number

The index of the next video segment to be downloaded from
player.hls.media.


player.hls.segmentXhrTime

Type: number

The number of milliseconds it took to download the last media segment.
This value is updated after each segment download completes.


player.hls.bandwidth

Type: number

The number of bits downloaded per second in the last segment download.
This value is used by the default implementation of selectPlaylist 
to select an appropriate bitrate to play.


player.hls.selectPlaylist

Type: function

A function that returns the media playlist object to use to download
the next segment. It is invoked by the tech immediately before a new
segment is downloaded. You can override this function to provide your
adaptive streaming logic. You must, however, be sure to return a valid
media playlist object that is present in player.hls.master.


Events


loadedmetadata

Fired after the first media playlist is downloaded for a stream.


loadedplaylist

Fired immediately after a new master or media playlist has been
downloaded. By default, the tech only downloads playlists as they
are needed.


Testing

For testing, you can either run npm test or use grunt directly.
If you use npm test, it will only run the karma tests using chrome.
You can specify which browsers you want the tests to run via grunt's test task.
You can use either grunt-style arguments or comma separated arguments:

grunt test:chrome:firefox   # grunt-style
grunt test:chrome,firefox   # comma-separated


Possible options are:


chromecanary
phantomjs
opera
chrome
safari
firefox
ie


Hosting Considerations

Unlike a native HLS implementation, the HLS tech has to comply with
the browser's security policies. That means that all the files that
make up the stream must be served from the same domain as the page
hosting the video player or from a server that has appropriate CORS
headers
configured. Easy instructions are
available for popular webservers
and most CDNs should have no trouble turning CORS on for your account.


MBR Rendition Selection Logic

In situations where manifests have multiple renditions, the player will
go through the following algorithm to determine the best rendition by
bandwidth and viewport dimensions.


Start on index 0 as defined in the HLS Spec (link above)
On a successful load complete per segment determine the following;


player.hls.bandwidth set to value as segment byte size over download time
Viewport width/height as determined by player.width()/player.height()
Playlists mapped and sorted by BANDWIDTH less than or equal to 1.1x player.hls.bandwidth
Best playlist variant by BANDWIDTH determined
Subset of bandwidth appropriate renditions mapped
Subset validated for RESOLUTION attributes less than or equal to player dimensions
Best playlist variant by RESOLUTION determined


Result is as follows;


[Best RESOLUTION variant] OR [Best BANDWIDTH variant] OR [inital playlist in manifest]


Release History


0.7.0: convert the HLS plugin to a tech
0.6.0:


Refactor playlist loading
Add testing via karma


0.5.0: cookie-based content protection support (see withCredentials)
0.4.0: Live stream support
0.3.0: Performance fixes for high-bitrate streams
0.2.0: Basic playback and adaptive bitrate selection
0.1.0: Initial release