TRACTION Toolset

Description

The Pre-Recorded Content Adaptation solution contains a DASH-based 2D web player and a novel audio-prioritised adaptation solution for 2D content streaming.

The Pre-Recorded Content Adaptation Algorithm for the TRACTION EU-project is used to select the appropriate bitrates during on-demand content streaming to guarantee viewers’ good QoE. It considers differents parameters such as bandwidth, buffer level, quality variation, and stream priority. It tries to ensure the highest bitrate for audio, a key feature for performing arts pieces (opera in particular), while adapting the video quality given the bandwidth constraints. This is because many studies have shown that ensuring high audio quality can have a positive impact on viewers’ QoE.

Deployment

Setup

The TRACTION Pre-Recorded Content Adaptation Algorithm is deployed within the dash.js reference player under /PreRecordedContentAdaptation/src/streaming/rules/abr. The file containing the algorithm’s logic is PadaRule.js.

To use the Pre-Recorded Content Adaptation Algorithm, first you need to create a video element on your html file. 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, create a MediaPlayer and initialise it. The url attribute should contain the link to the mpd of your video.

var url = "https://PathToYourMPD/manifest.mpd";
var player = dashjs.MediaPlayer().create();
player.initialize(document.querySelector("#videoPlayer"), url, true);

To make the player use the Pre-Recorded Content Adaptation Algorthim, Labelled as abrPada, you need to update the player’s settings, particularly those related to abr.

player.updateSettings({
    'abr':{
        'ABRStrategy' : 'abrPada',
        'priority'    : 3,
    }
});

Note that priority denotes the priority of the stream. It’s mainly used for multi-streaming use cases. It has 3 values: high (3), medium (2), and low (1).

Once done, your html file should look like the following:

<!doctype html>
<html>
    <head>
        <title>My html</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 = "https://PathToYourMPD/manifest.mpd";
                var player = dashjs.MediaPlayer().create();
                player.initialize(document.querySelector("#videoPlayer"), url, true);
          
                player.updateSettings({
                  'abr':{
                        'ABRStrategy' : 'abrPada',
                        'priority'    : 3,
                   }
                });
            })();
        </script>
    </body>
</html>

Data Collection

The dash player enables the collection of some QoS metrics such as buffer level, throughput, and selected bitrate.

var bufferLevel = player.getBufferLength('type');
var throughput  = player.getAverageThroughput('type');
var quality     = player.getQualityFor('type');

type denotes the segment type (i.e., video, audio). These metrics along with others can help assess the adaptation algorithm.

Adding/ modifying the Pre-Recorded Content Adaptation Algorithm

To be able to add or modify PadaRule.js, you need to do the following steps:

Install node.js.
Checkout the project repository (git clone https://github.com/traction-project/PreRecordedContentAdaptation.git).
Install dependencies (npm install).
Add or make changes to PadaRule.js.
Build, watch file changes, and launch samples page (npm run start).

dash.js Documentation

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

For help, join Slack channel or the email list.

Pre-Recorded Content Adaptation

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