The RTVIObserver translates Pipecat’s internal pipeline events into standardized RTVI protocol messages. It monitors frame flow through the pipeline and generates corresponding client messages based on event types.

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Purpose

The RTVIObserver serves two main functions:
  1. Converting internal pipeline frames to client-compatible RTVI messages
  2. Managing aggregated state for multi-frame events (like bot transcriptions)

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Adding to a Pipeline

The observer is attached to a pipeline task along with the RTVI processor: 
# Create the RTVIProcessor
rtvi = RTVIProcessor(config=RTVIConfig(config=[]))

# Add to pipeline
pipeline = Pipeline([
    transport.input(),
    rtvi,
    # Other processors...
])

# Create pipeline task with observer
task = PipelineTask(
    pipeline,
    params=PipelineParams(allow_interruptions=True),
    observers=[RTVIObserver(rtvi)],  # Add the observer here
)

​
Frame Translation

The observer maps Pipecat’s internal frames to RTVI protocol messages:
Pipeline FrameRTVI Message
Speech Events
UserStartedSpeakingFrameRTVIUserStartedSpeakingMessage
UserStoppedSpeakingFrameRTVIUserStoppedSpeakingMessage
BotStartedSpeakingFrameRTVIBotStartedSpeakingMessage
BotStoppedSpeakingFrameRTVIBotStoppedSpeakingMessage
Transcription
TranscriptionFrameRTVIUserTranscriptionMessage(final=true)
InterimTranscriptionFrameRTVIUserTranscriptionMessage(final=false)
LLM Processing
LLMFullResponseStartFrameRTVIBotLLMStartedMessage
LLMFullResponseEndFrameRTVIBotLLMStoppedMessage
LLMTextFrameRTVIBotLLMTextMessage
TTS Events
TTSStartedFrameRTVIBotTTSStartedMessage
TTSStoppedFrameRTVIBotTTSStoppedMessage
TTSTextFrameRTVIBotTTSTextMessage
Context/Metrics
OpenAILLMContextFrameRTVIUserLLMTextMessage
MetricsFrameRTVIMetricsMessage
RTVIServerMessageFrameRTVIServerMessage