matt's Soup!: mpeg

viernes, 13 de mayo de 2016

The State of MPEG-DASH 2016 (Part I)

The industry is turning away from plug-ins and embracing HTML5 everywhere. Here's how the vendor-independent streaming standard is gaining momentum.

If you ask industry experts about future streaming formats, most will say they see a combination of MPEG-DASH for the majority of new platforms and HLS for iOS and legacy devices. The move has begun, first with DASH replacing other ABR formats, such as HDS and Smooth Streaming, which are suffering from the no-plugin browser trend. The deprecation of the old Netscape Plugin API (NPAPI) in Chrome in September 2015 was the first major signal of this trend. As Microsoft didn’t want to issue a new version of the Silverlight plug-in using the new Chrome Pepper API (PPAPI), all content providers using Smooth Streaming through Silverlight-based players were forced to find an alternative. Some of them chose to stay with Smooth Streaming for now and use hasplayer.js (a fork of dash.js v1.2), which can play Smooth Streaming content through Media Source Extensions (MSE). But that’s risky for several reasons, including DRM support, since PlayReady is not supported in Chrome and would instead require an on-the-fly translation to Widevine Modular DRM. And for content providers delivering streams in the clear, Smooth Streaming over hasplayer.js is not an ideal long-term approach either, as the evolution of dash.js deviated from the cross-format support that was initially proposed by the framework. All the concerned content providers are now working on migrating their Smooth players to DASH for the most recent platforms, and to HLS for legacy platforms, such as the Xbox 360, where DASH support needs extra development.

NEXT: Part II >

Kickstart your OTT triials with this MPEG DASH tutorial

A reference client implementation for the playback of MPEG DASH via JavaScript and compliant browsers. Learn more about DASH IF Reference Client on our wiki.

If your intent is to use the player code without contributing back to this project, then use the MASTER branch which holds the approved and stable public releases.

If your goal is to improve or extend the code and contribute back to this project, then you should make your changes in, and submit a pull request against, the DEVELOPMENT branch. Read through our wiki section on https://github.com/Dash-Industry-Forum/dash.js/wiki/How-to-Contribute for a walk-through of the contribution process.

All new work should be in the development branch. Master is now reserved for tagged builds.

Before you get started, please read the Dash.js v2.0 Migration Document found here

Full API Documentation is available describing all public methods, interfaces, properties, and events.

For help, join our Slack channel, our email list and read our wiki.

Reference players

The released pre-built reference players are publicly accessible if you want direct access without writing any Javascript.

The nightly build of the /dev branch reference player, is pre-release but contains the latest fixes. It is a good place to start if you are debugging playback problems.

A nightly build of the latest minified files are also available: dash.all.min.js and its debug version dash.all.debug.js.

Quick Start for Users

If you just want a DASH player to use and don't need to see the code or commit to this project, then follow the instructions below. If you are a developer and want to work with this code base, then skip down to the "Quick Start for Developers" section.

Put the following code in your web page

<script src="http://cdn.dashjs.org/latest/dash.all.min.js"></script>
...
<style>
    video {
       width: 640px;
       height: 360px;
    }
</style>
...
<body>
   <div>
       <video data-dashjs-player autoplay src="http://dash.edgesuite.net/envivio/EnvivioDash3/manifest.mpd" controls></video>
   </div>
</body>

Then place your page under a web server (do not try to run from the file system) and load it via http in a MSE-enabled browser. The video will start automatically. Switch out the manifest URL to your own manifest once you have everything working. If you prefer to use the latest code from this project (versus the last tagged release) then see the "Quick Start for Developers" section below.

View the /samples folder for many other examples of embedding and using the player.

Quick Start for Developers

Reference Player

Download 'development' branch
Extract dash.js and move the entire folder to localhost (or run any http server instance such as python's SimpleHTTPServer at the root of the dash.js folder).
Open samples/dash-if-reference-player/index.html in your MSE capable web browser.

Install Core Dependencies

install nodejs
install grunt
- npm install -g grunt-cli

Build / Run tests on commandline.

Install all Node Modules defined in package.json
- npm install
Run the GruntFile.js default task
- grunt
You can also target individual tasks: E.g.
- grunt debug (quickest build)
- grunt dist
- grunt release
- grunt test

Getting Started

The standard setup method uses javascript to initialize and provide video details to dash.js. MediaPlayerFactory provides an alternative declarative setup syntax.

Standard Setup

Create a video element somewhere in your html. For our purposes, make sure the controls attribute is present.

<video id="videoPlayer" controls></video>

Add dash.all.min.js to the end of the body.

<body>
  ...
  <script src="yourPathToDash/dash.all.min.js"></script>
</body>

Now comes the good stuff. We need to create a MediaPlayer and initialize it.

var url = "http://dash.edgesuite.net/envivio/EnvivioDash3/manifest.mpd";
var player = dashjs.MediaPlayer().create();
player.initialize(document.querySelector("#videoPlayer"), url, true);

When it is all done, it should look similar to this:

<!doctype html>
<html>
    <head>
        <title>Dash.js Rocks</title>
        <style>
            video {
                width: 640px;
                height: 360px;
            }
        </style>
    </head>
    <body>
        <div>
            <video id="videoPlayer" controls></video>
        </div>
        <script src="yourPathToDash/dash.all.min.js"></script>
        <script>
            (function(){
                var url = "http://dash.edgesuite.net/envivio/EnvivioDash3/manifest.mpd";
                var player = dashjs.MediaPlayer().create();
                player.initialize(document.querySelector("#videoPlayer"), url, true);
            })();
        </script>
    </body>
</html>

Module Setup

We publish dash.js to npm. Examples of how to use dash.js in different module bundlers can be found in thesamples/modules directory.

MediaPlayerFactory Setup

An alternative way to build a Dash.js player in your web page is to use the MediaPlayerFactory. The MediaPlayerFactory will automatically instantiate and initialize the MediaPlayer module on appropriately tagged video elements.

Create a video element somewhere in your html and provide the path to your mpd file as src. Also ensure that your video element has the data-dashjs-player attribute on it.

<video data-dashjs-player autoplay src="http://dash.edgesuite.net/envivio/EnvivioDash3/manifest.mpd" controls>
</video>