Bandwidth detection Selecting the best bitrate based on available bandwidth

Introduction

The Bandwidth Check plugin is used to detect the bandwidth that is available to the player. Based on the result of this detection the plugin selects the stream or file that is best suited for the available bandwidth. This way the viewing experience of the user is optimal without unnecessary buffering in the middle of the stream. If the user has a broadband connection (large bandwidth) he will be served with a HD quality stream and will have a good viewing experience, and with slower connection speeds a file with a smaller bitrate will be selected.

Video (and audio) files are encoded with several different bitrates so that good matches are available for the connection speeds that are being targeted.

Download (Version 3.1.3)

Features

• Support for HTTP, pseudostreaming, and RTMP with Wowza, Red5, and Adobe FMS.
• Remembers the detected bandwidth so that it is checked only once for each user.
• Dynamic stream switching with Adobe FMS. Allows for seamless switching of the bitrate in the middle of viewing the stream.
• Manual selection of the bitrate. Users will be able to manually select the bitrate, overriding the detected value.
• Clustering of hosts. The plugin can be configured with a set of hosts it connects to when checking bandwidth. Failing servers are skipped and a working server is selected.

HTTP Example

This example demonstrates HTTP-based bandwidth checking:

Your speed appears here.

The configuration is shown below. This example uses HTTP to detect the bandwidth. It loads a reference file from the URL configured with netConnectionUrl and calculates the bandwidth based on the download speed and file size.

flowplayer("player", "http://releases.flowplayer.org/swf/flowplayer-3.1.5.swf", {
		
	// configure the required plugin
	plugins:  {
		
		// bandwidth check plugin
		bwcheck: {  
			url: 'flowplayer.bwcheck-3.1.3.swf',   
			netConnectionUrl: 'http://releases.flowplayer.org/swf/expressinstall.swf',
			bitrates: [40, 150, 400, 700, 1000],
		
			// this method is called when the bandwidth check is done
			onBwDone: function(url, chosenBitrate, bitrate) {
				var el = document.getElementById("info");
				el.innerHTML = "Your speed is: " +bitrate+ "<br />Video file served: " +url;
			}
		}
		
	},
	clip: {
		urlResolvers: 'bwcheck'
	}
	
});

You need to have different video files for each bitrate you wish to target. This configuration uses the following files and these need to all be available on the server:

• skyandice-150.flv
• skyandice-400.flv
• skyandice-700.flv
• skyandice-1000.flv

Configuration

Here is a list of the configuration options:

Bandwidth checking hosts can be clustered so that you can have many of them available to serve your files. If any of the checks fails, then another host is selected. The following configuration options are related to clustering:

You can assign labels to the bitrate values. These labels will be used when the filename is resolved. The labels are specified in the bitrates configuration variable:

// bitrates with their labels
	bitrates: { low: 256, mid: 512, high: 1024 },
	// our URL's have following extension
	urlExtension: 'mp4.smil'

With this configuration we get the following URLs when the original URL before bwcheck is "video.mp4.smil":

• video-low.mp4.smil
• video-mid.mp4.smil
• video-high.mp4.smil

The use of labels allows us to change the bitrates corresponding to the labels and the names of the files continue to make sense. Additionally the player configuration does not need to change.

RTMP Example

The bwcheck plugin supports RTMP servers such as Wowza, Red5 and Adobe FMS. Below is an example:

Click on the splash image above.

The configuration is shown below. Note that the serverType and urlPattern values that need to be defined for Adobe FMS.

flowplayer("rtmpPlayer", "http://releases.flowplayer.org/swf/flowplayer-3.1.5.swf", {

	// configure the required plugins
	plugins:  {

		// RTMP streaming plugin
		rtmp: {
			url: 'flowplayer.rtmp-3.1.3.swf',
			netConnectionUrl: 'rtmp://cyzy7r959.rtmphost.com/flowplayer'
		},

		// bandwidth check plugin
		bwcheck: {
			url: 'flowplayer.bwcheck-3.1.3.swf',

			// Influxis uses Flash Media Servers
			serverType: 'fms',

			// Use this connection for bandwidth detection
			netConnectionUrl: 'rtmp://cyzy7r959.rtmphost.com/flowplayer',

			// available bitrates for file names
			bitrates: [40, 150, 400, 700, 1000],

			// use a customized urlPattern for file names
			urlPattern: '{0}-{1}',

			// this method is called when the bandwidth check is done
			onBwDone: function(url, chosenBitrate, bitrate) {
				var el = document.getElementById("rtmpInfo");
				el.innerHTML = "Your speed is: " +bitrate+ "<br />Video file served: " +url;
			}
		}

	},

	// configure the clip to use the rtmp plugin for providing video data
	// and the bwcheck plugin in resolving the URLs
	clip: {
		provider: 'rtmp',
		
		// use bwcheck for all clips
		urlResolvers: 'bwcheck'
	}

});

With the Wowza server you need to install the bwcheck app that is bundled in the Wowza distribution. Similarily with Red5 you need to install its bwcheck application that can be installed using Red5's installer. With Adobe FMS bandwidth checking works without any extra steps.

Clustering of bandwidth checks

You can configure an array of hosts to be used for the bandwidth check. The plugin chooses a live host from this array until it finds one that does not fail. This provides a way to add failover. Here is an example configuration on how to configure clustering for the bandwidht check:

bwcheck: {
        url: 'flowplayer.rtmp-3.1.3.swf',
        serverType: 'red5',

        // the actual streaming happens from this host. In reality you would
        // probably configure a cluster of hosts here too.
        netConnectionUrl: 'rtmp://electroteque.org/bwcheck',

        // the hosts used for bandwidth checking
        hosts: [
            {host:'rtmp://electroteque1.org/bwcheck'},
            {host:'rtmp://electroteque2.org/bwcheck'},
            {host:'rtmp://electroteque.org/bwcheck'}
        ],

        defaultBitrate: 300,
        bitrates: [
            100,300,500,700
        ],
        //{0} is the filename, {1} is the bitrate, {2} is the extension
        urlPattern: '{0}-{1}.{2}'
    }

The configuration above is for clustering the bandwidth checking connections only. If you want to cluster your streaming connections, then you need to use our clustering plugin.

Dynamic stream switching

Dynamic stream switching is available in Adobe's FMS 3.5. In dynamic switching the available bandwidth is monitored while the stream plays and the stream is switched on-the-fly if the available bandwidth decreases or increases. See more information about dynamic stream switching in Dynamic stream switching with Flash Media Server 3.

Dynamic stream switching is configured just like RTMP bandwidth checking for Adobe FMS and by adding the option dynamic: true to the plugin's configuration. Here is a page demonstrating this in action.

Using it together with other plugins

You can use bandwidth checking together with other plugins like the secure streaming plugin. In fact it is possible to chain together 2 or more URL resolver plugins.

JavaScript API

Methods

Events

Here are the events related to establishing a connection and clustering. Note that if you are not clustering the hosts used for bandwidth checking, the host index will always have a value of zero.

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