Wyoming Protocol

A peer-to-peer protocol for voice assistants (basically JSONL + PCM audio)

{ "type": "...", "data": { ... }, "data_length": ..., "payload_length": ... }\n
<data_length bytes (optional)>
<payload_length bytes (optional)>

Used in Rhasspy and Home Assistant for communication with voice services.

This is an open standard of the Open Home Foundation.

Wyoming Projects

Voice satellites
- Satellite for Home Assistant
Audio input/output
Wake word detection
Speech-to-text
Text-to-speech
- Piper
Intent handling
- handle-external

Format

A JSON object header as a single line with \n (UTF-8, required)
- type - event type (string, required)
- data - event data (object, optional)
- data_length - bytes of additional data (int, optional)
- payload_length - bytes of binary payload (int, optional)
Additional data (UTF-8, optional)
- JSON object with additional event-specific data
- Merged on top of header data
- Exactly data_length bytes long
- Immediately follows header \n
Payload
- Typically PCM audio but can be any binary data
- Exactly payload_length bytes long
- Immediately follows additional data or header \n if no additional data

Event Types

Available events with type and fields.

Audio

Send raw audio and indicate begin/end of audio streams.

audio-chunk - chunk of raw PCM audio
- rate - sample rate in hertz (int, required)
- width - sample width in bytes (int, required)
- channels - number of channels (int, required)
- timestamp - timestamp of audio chunk in milliseconds (int, optional)
- Payload is raw PCM audio samples
audio-start - start of an audio stream
- rate - sample rate in hertz (int, required)
- width - sample width in bytes (int, required)
- channels - number of channels (int, required)
- timestamp - timestamp in milliseconds (int, optional)
audio-stop - end of an audio stream
- timestamp - timestamp in milliseconds (int, optional)

Info

Describe available services.

describe - request for available voice services
info - response describing available voice services
- asr - list speech recognition services (optional)
  - models - list of available models (required)
    - name - unique name (required)
    - languages - supported languages by model (list of string, required)
    - attribution (required)
      - name - name of creator (required)
      - url - URL of creator (required)
    - installed - true if currently installed (bool, required)
    - description - human-readable description (string, optional)
    - version - version of the model (string, optional)
- tts - list text to speech services (optional)
  - models - list of available models
    - name - unique name (required)
    - languages - supported languages by model (list of string, required)
    - speakers - list of speakers (optional)
      - name - unique name of speaker (required)
    - attribution (required)
      - name - name of creator (required)
      - url - URL of creator (required)
    - installed - true if currently installed (bool, required)
    - description - human-readable description (string, optional)
    - version - version of the model (string, optional)
- wake - list wake word detection services( optional )
  - models - list of available models (required)
    - name - unique name (required)
    - languages - supported languages by model (list of string, required)
    - attribution (required)
      - name - name of creator (required)
      - url - URL of creator (required)
    - installed - true if currently installed (bool, required)
    - description - human-readable description (string, optional)
    - version - version of the model (string, optional)
- handle - list intent handling services (optional)
  - models - list of available models (required)
    - name - unique name (required)
    - languages - supported languages by model (list of string, required)
    - attribution (required)
      - name - name of creator (required)
      - url - URL of creator (required)
    - installed - true if currently installed (bool, required)
    - description - human-readable description (string, optional)
    - version - version of the model (string, optional)
- intent - list intent recognition services (optional)
  - models - list of available models (required)
    - name - unique name (required)
    - languages - supported languages by model (list of string, required)
    - attribution (required)
      - name - name of creator (required)
      - url - URL of creator (required)
    - installed - true if currently installed (bool, required)
    - description - human-readable description (string, optional)
    - version - version of the model (string, optional)
- satellite - information about voice satellite (optional)
  - area - name of area where satellite is located (string, optional)
  - has_vad - true if the end of voice commands will be detected locally (boolean, optional)
  - active_wake_words - list of wake words that are actively being listend for (list of string, optional)
  - max_active_wake_words - maximum number of local wake words that can be run simultaneously (number, optional)
  - supports_trigger - true if satellite supports remotely-triggered pipelines
- mic - list of audio input services (optional)
  - mic_format - audio input format (required)
    - rate - sample rate in hertz (int, required)
    - width - sample width in bytes (int, required)
    - channels - number of channels (int, required)
- snd - list of audio output services (optional)
  - snd_format - audio output format (required)
    - rate - sample rate in hertz (int, required)
    - width - sample width in bytes (int, required)
    - channels - number of channels (int, required)

Speech Recognition

Transcribe audio into text.

transcribe - request to transcribe an audio stream
- name - name of model to use (string, optional)
- language - language of spoken audio (string, optional)
- context - context from previous interactions (object, optional)
transcript - response with transcription
- text - text transcription of spoken audio (string, required)
- context - context for next interaction (object, optional)

Text to Speech

Synthesize audio from text.

synthesize - request to generate audio from text
- text - text to speak (string, required)
- voice - use a specific voice (optional)
  - name - name of voice (string, optional)
  - language - language of voice (string, optional)
  - speaker - speaker of voice (string, optional)

Wake Word

Detect wake words in an audio stream.

detect - request detection of specific wake word(s)
- names - wake word names to detect (list of string, optional)
detection - response when detection occurs
- name - name of wake word that was detected (int, optional)
- timestamp - timestamp of audio chunk in milliseconds when detection occurred (int optional)
not-detected - response when audio stream ends without a detection

Voice Activity Detection

Detects speech and silence in an audio stream.

voice-started - user has started speaking
- timestamp - timestamp of audio chunk when speaking started in milliseconds (int, optional)
voice-stopped - user has stopped speaking
- timestamp - timestamp of audio chunk when speaking stopped in milliseconds (int, optional)

Intent Recognition

Recognizes intents from text.

recognize - request to recognize an intent from text
- text - text to recognize (string, required)
- context - context from previous interactions (object, optional)
intent - response with recognized intent
- name - name of intent (string, required)
- entities - list of entities (optional)
  - name - name of entity (string, required)
  - value - value of entity (any, optional)
- text - response for user (string, optional)
- context - context for next interactions (object, optional)
not-recognized - response indicating no intent was recognized
- text - response for user (string, optional)
- context - context for next interactions (object, optional)

Intent Handling

Handle structured intents or text directly.

handled - response when intent was successfully handled
- text - response for user (string, optional)
- context - context for next interactions (object, optional)
not-handled - response when intent was not handled
- text - response for user (string, optional)
- context - context for next interactions (object, optional)

Audio Output

Play audio stream.

played - response when audio finishes playing

Voice Satellite

Control of one or more remote voice satellites connected to a central server.

run-satellite - informs satellite that server is ready to run pipelines
pause-satellite - informs satellite that server is not ready anymore to run pipelines
satellite-connected - satellite has connected to the server
satellite-disconnected - satellite has been disconnected from the server
streaming-started - satellite has started streaming audio to the server
streaming-stopped - satellite has stopped streaming audio to the server

Pipelines are run on the server, but can be triggered remotely from the server as well.

run-pipeline - runs a pipeline on the server or asks the satellite to run it when possible
- start_stage - pipeline stage to start at (string, required)
- end_stage - pipeline stage to end at (string, required)
- wake_word_name - name of detected wake word that started this pipeline (string, optional)
  - From client only
- wake_word_names - names of wake words to listen for (list of string, optional)
  - From server only
  - start_stage must be "wake"
- announce_text - text to speak on the satellite
  - From server only
  - start_stage must be "tts"
- restart_on_end - true if the server should re-run the pipeline after it ends (boolean, default is false)
  - Only used for always-on streaming satellites

Timers

timer-started - a new timer has started
- id - unique id of timer (string, required)
- total_seconds - number of seconds the timer should run for (int, required)
- name - user-provided name for timer (string, optional)
- start_hours - hours the timer should run for as spoken by user (int, optional)
- start_minutes - minutes the timer should run for as spoken by user (int, optional)
- start_seconds - seconds the timer should run for as spoken by user (int, optional)
- command - optional command that the server will execute when the timer is finished
  - text - text of command to execute (string, required)
  - language - language of the command (string, optional)
timer-updated - timer has been paused/resumed or time has been added/removed
- id - unique id of timer (string, required)
- is_active - true if timer is running, false if paused (bool, required)
- total_seconds - number of seconds that the timer should run for now (int, required)
timer-cancelled - timer was cancelled
- id - unique id of timer (string, required)
timer-finished - timer finished without being cancelled
- id - unique id of timer (string, required)

Event Flow

→ is an event from client to server
← is an event from server to client

Service Description

→ describe (required)
← info (required)

Speech to Text

→ transcribe event with name of model to use or language (optional)
→ audio-start (required)
→ audio-chunk (required)
- Send audio chunks until silence is detected
→ audio-stop (required)
← transcript
- Contains text transcription of spoken audio

Text to Speech

→ synthesize event with text (required)
← audio-start
← audio-chunk
- One or more audio chunks
← audio-stop

Wake Word Detection

→ detect event with names of wake words to detect (optional)
→ audio-start (required)
→ audio-chunk (required)
- Keep sending audio chunks until a detection is received
← detection
- Sent for each wake word detection
→ audio-stop (optional)
- Manually end audio stream
← not-detected
- Sent after audio-stop if no detections occurred

Voice Activity Detection

→ audio-chunk (required)
- Send audio chunks until silence is detected
← voice-started
- When speech starts
← voice-stopped
- When speech stops

Intent Recognition

→ recognize (required)
← intent if successful
← not-recognized if not successful

Intent Handling

For structured intents:

→ intent (required)
← handled if successful
← not-handled if not successful

For text only:

→ transcript with text to handle (required)
← handled if successful
← not-handled if not successful

Audio Output

→ audio-start (required)
→ audio-chunk (required)
- One or more audio chunks
→ audio-stop (required)
← played

rhasspy/wyoming

Wyoming Protocol

Wyoming Projects

Format

Event Types

Audio

Info

Speech Recognition

Text to Speech

Wake Word

Voice Activity Detection

Intent Recognition

Intent Handling

Audio Output

Voice Satellite

Timers

Event Flow

Service Description

Speech to Text

Text to Speech

Wake Word Detection

Voice Activity Detection

Intent Recognition

Intent Handling

Audio Output