• How to configure MPEG-DASH packetization (mpegdashstreaming)

    This article describes properties in Wowza Streaming Engine™ media server software that you can use to control how the MPEG-DASH segmenter splits streams into segments suitable for playback on DASH players.

    Note: Wowza Streaming Engine 4.0.0 or later is required.

    Contents


    Wowza Streaming Engine Manager configuration
    XML configuration

    Wowza Streaming Engine Manager configuration


    You can configure the properties that control how the MPEG-DASH segmenter splits streams in Wowza Streaming Engine™ Manager. Use Streaming Engine Manager to manage the Wowza Streaming Engine media server software.

    Configure properties for live streams

    1. In the manager Welcome page, click the Applications tab at the top of the page.

    2. In the Applications contents panel, click the name of your live application (such as live).

    3. On the live application page Properties tab, click MPEG-DASH Streaming Packetizer in the Quick Links bar.

      Note: Access to the Properties tab is limited to administrators with advanced permissions. For more information, see Manage credentials.


    4. Click Edit in the MPEG-DASH Streaming Packetizer properties area. To enable a property, select the Enabled check box for the property. You can also change the value for an enabled property from its default setting. All time values are in milliseconds and the values are set on a per-application basis. Refer to the MPEG-DASH segmenter property reference below for more information about the individual properties you can use to manage the MPEG-DASH segmenter for live streams.



    5. Click Save, and then restart the application when prompted to apply the changes.

    Note: For more information about how to configure properties, see Configure properties. This article shows how to access and adjust default properties and how to add custom properties in Streaming Engine Manager.

    MPEG-DASH segmenter property reference

    • mpegdashChunkDurationTarget - Sets the duration of each chunk in milliseconds.

    • mpegdashMaxChunkCount - Sets the maximum number of chunks stored in the available chunk list.

    • mpegdashPlaylistChunkCount - Sets the number of items returned in the playlist.

    • mpegdashRepeaterChunkCount - Sets the number of chunks that are immediately sent from the origin to the edge after initial connection. This property is only required for Live Edge application types. A live edge application will have a StreamType of liverepeater-edge in the Application.xml file.

    Property details


    The audio and video packets from a live encoder enter the Wowza media server and are segmented into chunks based on time. The duration (in milliseconds) of each chunk is controlled by the mpegdashChunkDurationTarget property setting. The chunks are added to the available chunk list as they are created. The maximum number of chunks stored in the available chunk list is controlled by the mpegdashMaxChunkCount property setting. When a stream is requested by a DASH client, a manifest is returned that contains the [n] most recently added chunks. The number of items [n] returned in the manifest is controlled by the mpegdashPlaylistChunkCount setting.

    The live stream repeater system is used to deliver a single live stream in an origin/edge configuration to multiple edge servers. The first time an edge server requests a stream, it pulls the previously segmented chunks from the origin to the edge for delivery to the client. The mpegdashRepeaterChunkCount property setting controls the number of chunks that are immediately sent from the origin to the edge after the initial connection. It's best if this setting is equal to or greater than mpegdashPlaylistChunkCount but less then mpegdashMaxChunkCount.

    Notes:
    • Chunks must start on a keyframe so it's best to use a keyframe interval that is factor of the mpegdashChunkDurationTarget setting. For example, if mpegdashChunkDurationTarget is set to 10 seconds, use a keyframe interval of 2, 2.5, 5, or 10 seconds.

    • To estimate how much memory is used to store the chunks for a single live stream, use the following formula:
      [total-memory-mb] = ([stream-bitrate-kbps]/([1024-kb-per-mb]*[8-bits-per-byte])) * [mpegdashChunkDurationTarget-seconds] * [mpegdashMaxChunkCount]
      For example, a 500 kilobit per second (Kbps) stream will consume the following amount of memory given the default settings above:
      (500/(1024*8)) * 10 * 10 = 6 MB of memory

    Configure property for VOD streams

    You can control the video on demand (VOD) chunk size by adding the mpegdashChunkDurationTarget property to your VOD application configuration.

    1. In the manager Welcome page, click the Applications tab at the top of the page.

    2. In the Applications contents panel, click the name of your live application (such as vod).

    3. On the VOD application page Properties tab, click Custom in the Quick Links bar.

      Note: Access to the Properties tab in Streaming Engine Manager is limited to administrators with advanced permissions. For more information, see Manage credentials.
    4. In the Custom area, click Edit.

    5. Click Add Custom Property, specify the following custom property settings in the Add Custom Property dialog box, and then click Add.

      1. In Path, select /Root/Application/HTTPStreamer.

      2. In Name, enter mpegdashChunkDurationTarget.

      3. In Type, select Integer.

      4. In Value, enter a value (in milliseconds) to specify the default VOD chunk size.

    6. Click Save, and then restart the application when prompted.


    XML configuration


    If you configured the properties in Wowza Streaming Engine Manager, you can skip this section. If you make changes to [install-dir]/conf/[application]/Application.xml, any supported settings are displayed in the manager the next time it's started. All time values are in milliseconds.

    Configure properties for live streams

    1. Use a text editor to open the Application.xml file for your live application. Then add the properties described in the MPEG-DASH segmenter property reference above to the <LiveStreamPacketizer>/<Properties> container. Be sure to add the properties to the correct <Properties> container in Application.xml as there are several such containers in the file.
      <Property>
      	<Name>mpegdashChunkDurationTarget</Name>
      	<Value>10000</Value>
      	<Type>Integer</Type>
      </Property>
      <Property>
      	<Name>mpegdashMaxChunkCount</Name>
      	<Value>10</Value>
      	<Type>Integer</Type>
      </Property>
      <Property>
      	<Name>mpegdashPlaylistChunkCount</Name>
      	<Value>4</Value>
      	<Type>Integer</Type>
      </Property>
      <Property>
      	<Name>mpegdashRepeaterChunkCount</Name>
      	<Value>4</Value>
      	<Type>Integer</Type>
      </Property>
    2. Restart the Wowza media server software to apply the changes.

    Configure property for VOD streams

    1. Open the Application.xml file for your VOD application using a text editor and then add the mpeg-dashChunkDurationTarget property to the <HTTPStreamer>/<Properties> container. Be sure the to add the properties to the correct <Properties> container in Application.xml as there are several such containers in the file.
      <Property>
      	<Name>mpegdashChunkDurationTarget</Name>
      	<Value>10000</Value>
      	<Type>Integer</Type>
      </Property>
    2. Restart the Wowza media server software.


    Originally Published: For Wowza Streaming Engine 4.0.0 on 11-25-2014.

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