> ## Documentation Index > Fetch the complete documentation index at: https://docs.chariot.in/llms.txt > Use this file to discover all available pages before exploring further. # TTS WebSocket > Bidirectional text-to-speech channel. Authenticate with the `chariotai-api-key` header, or with the `api_key` query parameter when your client cannot set handshake headers. Binary frames carrying audio are interleaved between the `audio.start` and `audio.done` messages and are not modelled as JSON messages below. The connection closes with code `1000` on success, `1008` on an auth or parameter problem, `1011` on an upstream failure, and `4402` when the workspace runs out of credits. ## AsyncAPI ````yaml api-reference/asyncapi.yaml ttsStream id: ttsStream title: Text to speech stream description: > Bidirectional text-to-speech channel. Authenticate with the `chariotai-api-key` header, or with the `api_key` query parameter when your client cannot set handshake headers. Binary frames carrying audio are interleaved between the `audio.start` and `audio.done` messages and are not modelled as JSON messages below. The connection closes with code `1000` on success, `1008` on an auth or parameter problem, `1011` on an upstream failure, and `4402` when the workspace runs out of credits. servers: - id: production protocol: wss host: api.chariot.in bindings: [] variables: [] address: /v1/tts/ws parameters: [] bindings: - protocol: ws version: 0.1.0 value: method: GET query: type: object required: - voice_id properties: voice_id: type: string format: uuid description: > Required. UUID of the voice to synthesize with. Get one from `GET /v1/voices`. examples: &ref_0 - bac7d666-094d-4698-91fa-741d60fce662 response_format: type: string enum: - pcm - wav default: pcm examples: &ref_1 - pcm description: > Encoding of the binary audio frames. `pcm` is raw signed 16-bit little-endian PCM; `wav` is a streaming WAV (RIFF header followed by PCM). Defaults to `pcm`. idle_timeout: type: number default: 60 exclusiveMinimum: 0 maximum: 300 examples: &ref_2 - 60 description: > Seconds the server waits for a client message before closing the session as idle. Must be greater than 0 and at most 300. Defaults to 60. enable_logging: type: boolean default: false examples: &ref_3 - false description: > When true, each generated segment is archived to your TTS history and the audio is stored for later retrieval. Defaults to false. api_key: type: string description: > Your API key. No default. Prefer the `chariotai-api-key` header where your client supports it, and use this query parameter only when the client cannot set handshake headers. schemaProperties: - name: method type: string description: GET required: false - name: query type: object required: false properties: - name: voice_id type: string description: > Required. UUID of the voice to synthesize with. Get one from `GET /v1/voices`. examples: *ref_0 required: true - name: response_format type: string description: > Encoding of the binary audio frames. `pcm` is raw signed 16-bit little-endian PCM; `wav` is a streaming WAV (RIFF header followed by PCM). Defaults to `pcm`. enumValues: - pcm - wav examples: *ref_1 required: false - name: idle_timeout type: number description: > Seconds the server waits for a client message before closing the session as idle. Must be greater than 0 and at most 300. Defaults to 60. examples: *ref_2 required: false - name: enable_logging type: boolean description: > When true, each generated segment is archived to your TTS history and the audio is stored for later retrieval. Defaults to false. examples: *ref_3 required: false - name: api_key type: string description: > Your API key. No default. Prefer the `chariotai-api-key` header where your client supports it, and use this query parameter only when the client cannot set handshake headers. required: false operations: - &ref_7 id: sendToChariot title: Client to server description: Messages you send to Chariot. type: receive messages: - &ref_9 id: inputText payload: - name: Append text description: >- Add text to the server's buffer. Does not generate audio on its own. type: object properties: - name: type type: string description: input.text required: true - name: text type: string description: The text to append to the buffer. examples: &ref_4 - 'Hello and welcome. ' required: true headers: [] jsonPayloadSchema: type: object required: - type - text properties: type: type: string const: input.text x-parser-schema-id: text: type: string description: The text to append to the buffer. examples: *ref_4 x-parser-schema-id: x-parser-schema-id: title: Append text description: Add text to the server's buffer. Does not generate audio on its own. example: |- { "type": "", "text": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: inputText - &ref_10 id: inputFlush payload: - name: Flush and generate description: > Synthesize everything currently buffered and stream the audio back. The session stays open. Flushing is what triggers generation. type: object properties: - name: type type: string description: input.flush required: true headers: [] jsonPayloadSchema: type: object required: - type properties: type: type: string const: input.flush x-parser-schema-id: x-parser-schema-id: title: Flush and generate description: > Synthesize everything currently buffered and stream the audio back. The session stays open. Flushing is what triggers generation. example: |- { "type": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: inputFlush - &ref_11 id: inputDone payload: - name: End input description: > Signal that no more text is coming. The server flushes the remainder and finishes the session. type: object properties: - name: type type: string description: input.done required: true headers: [] jsonPayloadSchema: type: object required: - type properties: type: type: string const: input.done x-parser-schema-id: x-parser-schema-id: title: End input description: > Signal that no more text is coming. The server flushes the remainder and finishes the session. example: |- { "type": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: inputDone bindings: [] extensions: &ref_6 - id: x-parser-unique-object-id value: ttsStream - &ref_8 id: receiveFromChariot title: Server to client description: Messages Chariot sends back to you. type: send messages: - &ref_12 id: audioStart payload: - name: Segment started description: A new audio segment is about to stream as binary frames. type: object properties: - name: type type: string description: audio.start required: false - name: sentence_index type: integer description: Zero-based index of this segment within the session. required: false - name: sentence_text type: string description: The text being spoken in this segment. required: false - name: format type: string enumValues: - pcm - wav required: false - name: sample_rate type: integer required: false headers: [] jsonPayloadSchema: type: object properties: type: type: string const: audio.start x-parser-schema-id: sentence_index: type: integer description: Zero-based index of this segment within the session. x-parser-schema-id: sentence_text: type: string description: The text being spoken in this segment. x-parser-schema-id: format: type: string enum: - pcm - wav x-parser-schema-id: sample_rate: type: integer default: 44100 x-parser-schema-id: x-parser-schema-id: title: Segment started description: A new audio segment is about to stream as binary frames. example: |- { "type": "", "sentence_index": 123, "sentence_text": "", "format": "", "sample_rate": 123 } bindings: [] extensions: - id: x-parser-unique-object-id value: audioStart - &ref_13 id: audioDone payload: - name: Segment finished description: > The current segment has finished streaming. Carries the credits charged for this segment. type: object properties: - name: type type: string description: audio.done required: false - name: sentence_index type: integer required: false - name: total_bytes type: integer description: Total bytes of audio streamed for this segment. required: false - name: credits_utilized type: integer description: Credits charged for this segment (1 per character). required: false headers: [] jsonPayloadSchema: type: object properties: type: type: string const: audio.done x-parser-schema-id: sentence_index: type: integer x-parser-schema-id: total_bytes: type: integer description: Total bytes of audio streamed for this segment. x-parser-schema-id: credits_utilized: type: integer description: Credits charged for this segment (1 per character). x-parser-schema-id: x-parser-schema-id: title: Segment finished description: > The current segment has finished streaming. Carries the credits charged for this segment. example: |- { "type": "", "sentence_index": 123, "total_bytes": 123, "credits_utilized": 123 } bindings: [] extensions: - id: x-parser-unique-object-id value: audioDone - &ref_14 id: sessionDone payload: - name: Session complete description: > All segments are complete. The server then closes the connection with code 1000. type: object properties: - name: type type: string description: session.done required: false - name: total_sentences type: integer required: false headers: [] jsonPayloadSchema: type: object properties: type: type: string const: session.done x-parser-schema-id: total_sentences: type: integer x-parser-schema-id: x-parser-schema-id: title: Session complete description: > All segments are complete. The server then closes the connection with code 1000. example: |- { "type": "", "total_sentences": 123 } bindings: [] extensions: - id: x-parser-unique-object-id value: sessionDone - &ref_15 id: errorMessage payload: - name: Error description: > An error occurred. Terminal errors carry a `code` matching the WebSocket close code that follows. type: object properties: - name: type type: string description: error required: false - name: code type: integer description: > Matches the close code, for example 4402 for insufficient credits. required: false - name: message type: string examples: &ref_5 - insufficient credits required: false headers: [] jsonPayloadSchema: type: object properties: type: type: string const: error x-parser-schema-id: code: type: integer description: > Matches the close code, for example 4402 for insufficient credits. x-parser-schema-id: message: type: string examples: *ref_5 x-parser-schema-id: x-parser-schema-id: title: Error description: > An error occurred. Terminal errors carry a `code` matching the WebSocket close code that follows. example: |- { "type": "", "code": 123, "message": "" } bindings: [] extensions: - id: x-parser-unique-object-id value: errorMessage bindings: [] extensions: *ref_6 sendOperations: - *ref_7 receiveOperations: - *ref_8 sendMessages: - *ref_9 - *ref_10 - *ref_11 receiveMessages: - *ref_12 - *ref_13 - *ref_14 - *ref_15 extensions: - id: x-parser-unique-object-id value: ttsStream securitySchemes: [] ````