The fixH264VideoNALLenStartcodeMix property will attempt to fix irregular nal sizes and start codes. Wirecast 5 is subject to this when the “timecode every” feature is not set.
Streams/Properties container in conf/[application]/Application.xml:
<Property>
<Name>fixH264VideoNALLenStartcodeMix</Name>
<Value>true</Value>
<Type>Boolean</Type>
</Property>
This property is valid >= 4.1.1