> ## Documentation Index > Fetch the complete documentation index at: https://docs.slng.ai/llms.txt > Use this file to discover all available pages before exploring further. # Inworld Max 1.5 > Stream multilingual speech synthesis from SLNG-hosted Inworld Max 1.5 over WebSocket using SLNG's unified low-latency TTS protocol. ## AsyncAPI ````yaml api-reference/asyncapi/tts-slng.asyncapi.yaml /v1/tts/slng/inworld/max:1.5 id: /v1/tts/slng/inworld/max:1.5 title: Inworld Max 1.5 description: >- Stream multilingual speech synthesis from SLNG-hosted Inworld Max 1.5 over WebSocket using SLNG's unified low-latency TTS protocol. servers: - id: production protocol: wss host: api.slng.ai bindings: [] variables: [] address: /v1/tts/slng/inworld/max:1.5 parameters: [] bindings: - protocol: ws version: latest value: method: GET headers: type: object properties: X-Region-Override: type: string description: >- Target region override. Auto-selected if not provided. Available regions: `us-east-1`. enum: - us-east-1 x-parser-schema-id: x-parser-schema-id: WebsocketHeadersSlngInworldMax schemaProperties: - name: method type: string description: GET required: false - name: headers type: object required: false properties: - name: X-Region-Override type: string description: >- Target region override. Auto-selected if not provided. Available regions: `us-east-1`. enumValues: - us-east-1 required: false operations: - &ref_1 id: ttsSlngInworldMaxReceiveInit title: Tts slng inworld max receive init description: Initialize session on Inworld Max 1.5 type: receive messages: - &ref_8 id: SlngInworldMaxInitRequest contentType: application/json payload: - name: Init Request (Inworld Max 1.5) description: Initialize an SLNG-hosted Inworld Max 1.5 session. type: object properties: - name: type type: string description: init required: true - name: voice type: string description: >- Inworld voice ID. Voices are multilingual — each has a native language but can speak any supported language via the `language` parameter (best results when `language` matches the voice's native language). See the full catalog at https://docs.slng.ai/voices/inworld. required: false - name: modelId type: string description: ID of the Inworld TTS model. enumValues: - inworld-tts-1.5-max required: false - name: language type: string description: >- BCP-47 language tag specifying the language the voice should speak the text in. Optional — when omitted, Inworld uses the voice's original prompt and auto-detects the language from the text. Voices are multilingual; best results when this matches the voice's native language. These are the 15 core languages supported by inworld-tts-1.5-max (inworld-tts-2 additionally supports ~85 experimental languages). An invalid code returns an error. enumValues: - ar-SA - de-DE - en-US - es-ES - fr-FR - he-IL - hi-IN - it-IT - ja-JP - ko-KR - nl-NL - pl-PL - pt-BR - ru-RU - zh-CN required: false - name: deliveryMode type: string description: >- Only applies to inworld-tts-2. Controls output variation; ignored on Max 1.5. enumValues: - DELIVERY_MODE_UNSPECIFIED - STABLE - BALANCED - CREATIVE required: false - name: temperature type: number description: >- Higher values produce more expressive output; lower values more deterministic. Range (0, 2]. required: false - name: timestampType type: string description: >- Controls timestamp metadata returned with the audio. Adds latency. enumValues: - TIMESTAMP_TYPE_UNSPECIFIED - WORD - CHARACTER required: false - name: applyTextNormalization type: string description: >- Expands numbers, dates, and abbreviations before synthesis. Disabling may reduce latency. enumValues: - APPLY_TEXT_NORMALIZATION_UNSPECIFIED - 'ON' - 'OFF' required: false - name: timestampTransportStrategy type: string description: >- Whether timestamp data arrives synchronously with audio or in trailing messages. enumValues: - TIMESTAMP_TRANSPORT_STRATEGY_UNSPECIFIED - SYNC - ASYNC required: false - name: autoMode type: boolean description: When enabled, the server controls flushing automatically. required: false - name: maxBufferDelayMs type: integer description: Maximum text buffering delay before synthesis starts. required: false - name: bufferCharThreshold type: integer description: Character buffer threshold before synthesis starts. required: false - name: encoding type: string description: >- Output audio format. Maps to Inworld audioConfig.audioEncoding. enumValues: - LINEAR16 - MP3 - OGG_OPUS - ALAW - MULAW - FLAC - PCM - WAV required: false - name: sample_rate type: integer description: >- Output sample rate in Hz. Maps to Inworld audioConfig.sampleRateHertz. enumValues: - 8000 - 16000 - 22050 - 24000 - 32000 - 44100 - 48000 required: false - name: bit_rate type: integer description: >- Bits per second. Only applies to compressed formats (MP3, OGG_OPUS). Maps to Inworld audioConfig.bitRate. required: false - name: speaking_rate type: number description: >- Playback speed. Values below 0.8 not recommended for quality. Maps to Inworld audioConfig.speakingRate. required: false headers: [] jsonPayloadSchema: type: object description: >- Initialize a session with voice and audio configuration. Sent once per WebSocket connection before any text frames. Audio output uses flat fields (encoding, sample_rate, bit_rate, speaking_rate) that the gateway maps to Inworld's audioConfig. required: - type properties: type: type: string const: init default: init x-parser-schema-id: voice: type: string default: Ashley description: >- Inworld voice ID. Voices are multilingual — each has a native language but can speak any supported language via the `language` parameter (best results when `language` matches the voice's native language). See the full catalog at https://docs.slng.ai/voices/inworld. x-parser-schema-id: modelId: type: string enum: - inworld-tts-1.5-max default: inworld-tts-1.5-max description: ID of the Inworld TTS model. x-parser-schema-id: language: type: string description: >- BCP-47 language tag specifying the language the voice should speak the text in. Optional — when omitted, Inworld uses the voice's original prompt and auto-detects the language from the text. Voices are multilingual; best results when this matches the voice's native language. These are the 15 core languages supported by inworld-tts-1.5-max (inworld-tts-2 additionally supports ~85 experimental languages). An invalid code returns an error. enum: - ar-SA - de-DE - en-US - es-ES - fr-FR - he-IL - hi-IN - it-IT - ja-JP - ko-KR - nl-NL - pl-PL - pt-BR - ru-RU - zh-CN x-parser-schema-id: SlngInworldMaxLanguage deliveryMode: type: string enum: - DELIVERY_MODE_UNSPECIFIED - STABLE - BALANCED - CREATIVE description: >- Only applies to inworld-tts-2. Controls output variation; ignored on Max 1.5. x-parser-schema-id: temperature: type: number exclusiveMinimum: 0 maximum: 2 default: 1 description: >- Higher values produce more expressive output; lower values more deterministic. Range (0, 2]. x-parser-schema-id: timestampType: type: string enum: - TIMESTAMP_TYPE_UNSPECIFIED - WORD - CHARACTER default: TIMESTAMP_TYPE_UNSPECIFIED description: >- Controls timestamp metadata returned with the audio. Adds latency. x-parser-schema-id: applyTextNormalization: type: string enum: - APPLY_TEXT_NORMALIZATION_UNSPECIFIED - 'ON' - 'OFF' default: APPLY_TEXT_NORMALIZATION_UNSPECIFIED description: >- Expands numbers, dates, and abbreviations before synthesis. Disabling may reduce latency. x-parser-schema-id: timestampTransportStrategy: type: string enum: - TIMESTAMP_TRANSPORT_STRATEGY_UNSPECIFIED - SYNC - ASYNC description: >- Whether timestamp data arrives synchronously with audio or in trailing messages. x-parser-schema-id: autoMode: type: boolean description: When enabled, the server controls flushing automatically. x-parser-schema-id: maxBufferDelayMs: type: integer description: Maximum text buffering delay before synthesis starts. x-parser-schema-id: bufferCharThreshold: type: integer minimum: 0 maximum: 1000 description: Character buffer threshold before synthesis starts. x-parser-schema-id: encoding: type: string enum: - LINEAR16 - MP3 - OGG_OPUS - ALAW - MULAW - FLAC - PCM - WAV default: MP3 description: Output audio format. Maps to Inworld audioConfig.audioEncoding. x-parser-schema-id: sample_rate: type: integer enum: - 8000 - 16000 - 22050 - 24000 - 32000 - 44100 - 48000 default: 48000 description: >- Output sample rate in Hz. Maps to Inworld audioConfig.sampleRateHertz. x-parser-schema-id: bit_rate: type: integer description: >- Bits per second. Only applies to compressed formats (MP3, OGG_OPUS). Maps to Inworld audioConfig.bitRate. x-parser-schema-id: speaking_rate: type: number minimum: 0.5 maximum: 1.5 default: 1 description: >- Playback speed. Values below 0.8 not recommended for quality. Maps to Inworld audioConfig.speakingRate. x-parser-schema-id: x-parser-schema-id: title: Init Request (Inworld Max 1.5) description: Initialize an SLNG-hosted Inworld Max 1.5 session. example: |- { "type": "init", "voice": "Ashley", "modelId": "inworld-tts-1.5-max", "language": "en-US", "encoding": "MP3", "sample_rate": 24000 } bindings: [] extensions: - id: x-parser-unique-object-id value: SlngInworldMaxInitRequest bindings: [] extensions: &ref_0 - id: x-parser-unique-object-id value: /v1/tts/slng/inworld/max:1.5 - &ref_2 id: ttsSlngInworldMaxReceiveText title: Tts slng inworld max receive text description: Send text to Inworld Max 1.5 type: receive messages: - &ref_9 id: TtsTextMessage contentType: application/json payload: - name: Text Message description: Send text to synthesize into audio output. type: object properties: - name: type type: string description: text required: true - name: text type: string description: Text to synthesize required: true - name: flush type: boolean description: Whether to flush remaining audio immediately after this text required: false headers: [] jsonPayloadSchema: type: object description: Send text to synthesize into audio output. required: - type - text properties: type: type: string const: text x-parser-schema-id: text: type: string description: Text to synthesize x-parser-schema-id: flush: type: boolean description: Whether to flush remaining audio immediately after this text x-parser-schema-id: x-parser-schema-id: title: Text Message description: Send text to synthesize into audio output. example: |- { "type": "text", "text": "Hello, this is a test of text-to-speech synthesis." } bindings: [] extensions: - id: x-parser-unique-object-id value: TtsTextMessage bindings: [] extensions: *ref_0 - &ref_3 id: ttsSlngInworldMaxReceiveFlush title: Tts slng inworld max receive flush description: Flush buffered output on Inworld Max 1.5 type: receive messages: - &ref_10 id: TtsFlushMessage contentType: application/json payload: - name: Flush Message description: Force any buffered text/audio to be finalized and delivered. type: object properties: - name: type type: string description: flush required: true headers: [] jsonPayloadSchema: type: object description: Force any buffered text/audio to be finalized and delivered. required: - type properties: type: type: string const: flush x-parser-schema-id: x-parser-schema-id: title: Flush Message description: Force any buffered text/audio to be finalized and delivered. example: |- { "type": "flush" } bindings: [] extensions: - id: x-parser-unique-object-id value: TtsFlushMessage bindings: [] extensions: *ref_0 - &ref_4 id: ttsSlngInworldMaxReceiveClose title: Tts slng inworld max receive close description: Close session on Inworld Max 1.5 type: receive messages: - &ref_11 id: TtsCloseMessage contentType: application/json payload: - name: Close Message description: Close the session and stop any further audio. type: object properties: - name: type type: string description: close required: true headers: [] jsonPayloadSchema: type: object description: Close the session and stop any further audio. required: - type properties: type: type: string const: close x-parser-schema-id: x-parser-schema-id: title: Close Message description: Close the session and stop any further audio. example: |- { "type": "close" } bindings: [] extensions: - id: x-parser-unique-object-id value: TtsCloseMessage bindings: [] extensions: *ref_0 - &ref_5 id: ttsSlngInworldMaxSendAudioChunk title: Tts slng inworld max send audio chunk description: Receive audio chunk from Inworld Max 1.5 type: send messages: - &ref_12 id: TtsAudioChunk contentType: application/json payload: - name: Audio Chunk description: Chunk of base64-encoded audio data. type: object properties: - name: type type: string description: audio_chunk required: true - name: data type: string description: Base64-encoded audio data required: true - name: sequence type: integer description: Sequence number for ordering chunks required: false headers: [] jsonPayloadSchema: type: object description: Chunk of base64-encoded audio data. required: - type - data properties: type: type: string const: audio_chunk x-parser-schema-id: data: type: string format: byte description: Base64-encoded audio data x-parser-schema-id: sequence: type: integer description: Sequence number for ordering chunks x-parser-schema-id: x-parser-schema-id: title: Audio Chunk description: Chunk of base64-encoded audio data. example: |- { "type": "audio_chunk", "data": "UklGRiQAAABXQVZFZm10IBAAAAABAAEA...", "sequence": 1 } bindings: [] extensions: - id: x-parser-unique-object-id value: TtsAudioChunk bindings: [] extensions: *ref_0 - &ref_6 id: ttsSlngInworldMaxSendAudioEnd title: Tts slng inworld max send audio end description: Receive audio end from Inworld Max 1.5 type: send messages: - &ref_13 id: TtsAudioEnd contentType: application/json payload: - name: Audio End description: Signals the end of audio generation. type: object properties: - name: type type: string description: audio_end required: true - name: duration type: number description: Total audio duration required: false headers: [] jsonPayloadSchema: type: object description: Signals the end of audio generation. required: - type properties: type: type: string const: audio_end x-parser-schema-id: duration: type: number description: Total audio duration x-parser-schema-id: x-parser-schema-id: title: Audio End description: Signals the end of audio generation. example: |- { "type": "audio_end", "duration": 3.5 } bindings: [] extensions: - id: x-parser-unique-object-id value: TtsAudioEnd bindings: [] extensions: *ref_0 - &ref_7 id: ttsSlngInworldMaxSendError title: Tts slng inworld max send error description: Receive error from Inworld Max 1.5 type: send messages: - &ref_14 id: TtsErrorResponse contentType: application/json payload: - name: Error Response description: Indicates an error occurred during synthesis. type: object properties: - name: type type: string description: error required: true - name: code type: string description: Error code. enumValues: - auth_error - config_error - rate_limit - provider_error required: true - name: message type: string description: Human-readable error description required: true headers: [] jsonPayloadSchema: type: object description: Indicates an error occurred during synthesis. required: - type - code - message properties: type: type: string const: error x-parser-schema-id: code: type: string description: Error code. enum: - auth_error - config_error - rate_limit - provider_error x-parser-schema-id: message: type: string description: Human-readable error description x-parser-schema-id: x-parser-schema-id: title: Error Response description: Indicates an error occurred during synthesis. example: |- { "type": "error", "code": "provider_error", "message": "Provider returned an unexpected error" } bindings: [] extensions: - id: x-parser-unique-object-id value: TtsErrorResponse bindings: [] extensions: *ref_0 sendOperations: - *ref_1 - *ref_2 - *ref_3 - *ref_4 receiveOperations: - *ref_5 - *ref_6 - *ref_7 sendMessages: - *ref_8 - *ref_9 - *ref_10 - *ref_11 receiveMessages: - *ref_12 - *ref_13 - *ref_14 extensions: - id: x-parser-unique-object-id value: /v1/tts/slng/inworld/max:1.5 securitySchemes: - id: bearer name: bearer type: http description: > API key issued by SLNG. Pass as `Authorization: Bearer ` in the WebSocket upgrade request headers. scheme: bearer extensions: [] ````