The

before_llm_cb

parameter is used as a replacement for the deprecated

will_synthesize_assistant_reply

parameter. Here are some key points about its usage: • Returning

None

will create a default LLM stream. • You can return your own LLM stream by calling the

llm.chat()

method. • Returning

False

will cancel the synthesis of the reply. Unfortunately, the sources do not provide specific implementation details or examples for using

before_llm_cb()

in LLM streaming. If you need further assistance, please let me know! Sources: livekit.agents.voice_assistant API documentation