OptionalsegmentOptionallanguageOptionaltextOptionalaudioOptionalpcmBase64-encoded 16-bit LE mono PCM for source-language live listen.
OptionalsampleSample rate Hz for source_pcm payloads.
OptionalliveOptionalmessageOptionalactivityWhether the owner audio currently holds speech or music. Sent on transitions
and with the initial status event so listeners joining mid-song see the marker.
Caption/audio event pushed to public SSE subscribers.