Use video decoding parameters with the Transcoder in Wowza Streaming Engine

This article describes how to control video decoding using the Wowza Streaming Engine™ media server software Transcoder. Users with advanced decoding knowledge can log all of the video decoding parameters that are available, and their current values, and use this information to adjust the transcoding parameters for transcoded streams.

Note: A Transcoder template has just one <Decode> block (<Decode>...</Decode>), which represents the decoding process. Video-decoding parameters you apply will affect all transcoded streams. For more control over transcoding, you can apply video parameters to individual stream output renditions as they're transcoded. See Use video encoding parameters with the Transcoder in Wowza Streaming Engine.

Contents


Logging available video decoding parameters
Configuring video decoding parameters
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Logging available video decoding parameters


When using Transcoder, you can log all available video decoding parameters with their current values for the <Decode> block to the wowzastreamingengine_access.log file. To do this, open the Transcoder template in a text editor and add the following property to the <Properties> container in the <Decode> block in the template:

<Property>
    <Name>logVideoDecodingParameters</Name>
    <Value>true</Value>
    <Type>Boolean</Type>
</Property>

A section of the data logged in the wowzastreamingengine_access.log file might look like this:

# long: deinterlaceDoubleRate: 0:single rate (default), 1:double rate
default.deinterlaceDoubleRate: 0

You can then use this information as a basis for adjusting the transcoded video using the available video decoding parameters that are logged.

Note: The data logged will vary depending on the hardware in use and the codec applied to each transcoded output rendition. Advanced Beamr decoding parameters are not available.

Configuring video decoding parameters


You must use a text editor to configure video parameters in the transcoder template files ([install-dir]/transcoder/templates) in your Wowza Streaming Engine installation. They can't be configured using Wowza Streaming Engine Manager.

Open the Transcoder template in a text editor and add a <Parameter> section to the <Video>/<Parameters> container in the <Decode> block, as shown in the example below. Then restart Wowza Streaming Engine for the changes to take effect.

Note: Older versions of the example templates may not have a <Parameters> container for the <Video> decoding section. Add this container if it's missing from your template.

Example configuration

As an example, for this deinterlace rate method video parameter defined as available and in use in the wowzastreamingengine_access.log file:

# long: deinterlaceDoubleRate: 0:single rate (default), 1:double rate
default.deinterlaceDoubleRate: 0

You can use this information to change the deinterlace rate method being used by adding the following <Parameter> section to the <Video>/<Parameters> container in the <Decode> block in the template.

<Parameter>
    <!-- 0:single rate (default), 1:double rate -->
    <Name>default.deinterlaceDoubleRate</Name>
    <Value>0</Value>
    <Type>Long</Type>
</Parameter>
 
Note: Logs do not report a warning or error for invalid parameter values. If you specify an invalid value, the Transcoder uses the default value for the parameter instead, which is reflected in the logs.

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