The Transcoder in Wowza Streaming Engine™ media server software and Wowza Media Server™ software (version 3.5 and and later) supports bi-directional frames (B-frames) when using the default encoder implementation and the Main or High Profile. B-frame generation is turned off by default. To enable B-frames for a given <Encode> block, in your Transcoder template, add the following parameter to the Video/Parameters container in the <Encode> block:
<Parameter> <Name>mainconcept.reordering_delay</Name> <Value>2</Value> <Type>Integer</Type> </Parameter>
The Value property specifies the number of B-frames to generate between each P-frame. The number of B-frames generated is always one less than the specified value. So for example, a value of 2 instructs Transcoder to generate a single B-frame between each P-frame, a value of 3 instructs Transcoder to generate two B-frames between each P-frame, and so on. A value of 1 instructs Transcoder to generate zero B-frames between each P-frame, which effectively disables the feature.