--- title: "Synthesize Text via WebSocket" slug: "tts-synthesize-text-via-websocket" updated: 2026-05-12T08:58:02Z published: 2026-05-12T08:58:02Z --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.knovvu.com/llms.txt > Use this file to discover all available pages before exploring further. # Synthesize Text via WebSocket ## 1. Purpose This document explains how to use the TTS service over WebSocket. Through the WebSocket connection, text can be sent to the service, synthesized into audio, and the synthesis flow can be completed by sending the required control messages. --- ## 2. WebSocket Connection A WebSocket request can be created in Postman. **WebSocket URL Format:** ```text wss:///synthesizer ``` **Example:** ```text wss:///synthesizer ``` > Note: Actual environment URLs should not be shared openly in documentation. The relevant TTS WebSocket URL should be used depending on the target environment. --- ## 3. Message Flow After the WebSocket connection is established, the messages should be sent in the following order: ```text 1. synthesize 2. add-tts-text 3. flush 4. stop 5. finalize-synthesis ``` > Note: The separate `flush` message is required only when the `add-tts-text` message does not include the optional `flush` parameter. --- ## 4. Start Synthesis Message The first message should be the `synthesize` message. This message initializes the synthesis process and includes the audio format, voice, sample rate, volume, speaking rate, and authorization information. ### Request Format ```json { "message-name": "synthesize", "audio-format": "pcm", "voice-name": "", "sample-rate": "", "volume": "", "rate": "", "Authorization": "" } ``` ### Example ```json { "message-name": "synthesize", "audio-format": "pcm", "voice-name": "Emily_Premium", "sample-rate": "24000", "volume": "1.0", "rate": "1.0", "Authorization": "" } ``` ### Parameter Descriptions | Parameter | Description | Example Value | | --------------- | ------------------------------------ | ---------------- | | `message-name` | Specifies the message type. | `synthesize` | | `audio-format` | Specifies the output audio format. | `pcm` | | `voice-name` | Specifies the TTS voice to be used. | `Emily_Premium` | | `sample-rate` | Specifies the audio sample rate. | `24000` | | `volume` | Specifies the output volume level. | `1.0` | | `rate` | Specifies the speaking rate. | `1.0` | | `Authorization` | Access token used for authorization. | `` | > Security note: The actual access token should not be shared openly in documentation, emails, tickets, or any shared environment. --- ## 5. Text Message After the synthesis process is initialized, the text to be synthesized should be sent using the `add-tts-text` message. ### Request Format ```json { "message-name": "add-tts-text", "text": "" } ``` ### Example ```json { "message-name": "add-tts-text", "text": "Hello world. How are you today?" } ``` ### Parameter Descriptions | Parameter | Description | Example Value | | -------------- | ---------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------- | | `message-name` | Specifies the message type. | `add-tts-text` | | `text` | Contains the text to be synthesized. | `Hello world. How are you today?` | | `flush` | Optional parameter. If set to `true`, `yes`, or `1`, the text message is flushed immediately without sending a separate `flush` message. | `true` | ### Inline Flush Usage The `add-tts-text` message also supports an optional `flush` parameter. When this parameter is set to a truthy value such as `true`, `yes`, or `1`, the text message is flushed immediately. In this case, a separate `flush` message is not required for that specific text input. #### Example ```json { "message-name": "add-tts-text", "text": "Hello world. How are you today?", "flush": "true" } ``` > If the `flush` parameter is not provided, a separate `flush` message should be sent after the text message to trigger synthesis. --- ## 6. Flush Message After the text is sent, the `flush` message should be sent. This message indicates that the current text input is complete and should be processed by the service. A separate `flush` message is required only when the `add-tts-text` message does not include the optional `flush` parameter. ### Request Format ```json { "message-name": "flush" } ``` --- ## 7. Stop Message The `stop` message is used to stop the synthesis process. ### Request Format ```json { "message-name": "stop" } ``` --- ## 8. Finalize Synthesis Message The `finalize-synthesis` message is used to finalize and close the synthesis flow. ### Request Format ```json { "message-name": "finalize-synthesis" } ``` --- ## 9. Sample Message Sequence The following example shows the message sequence to be sent after the WebSocket connection is established. ### Option 1: Text Message Followed by Separate Flush #### 1. Start Message ```json { "message-name": "synthesize", "audio-format": "pcm", "voice-name": "Emily_Premium", "sample-rate": "24000", "volume": "1.0", "rate": "1.0", "Authorization": "" } ``` #### 2. Text Message ```json { "message-name": "add-tts-text", "text": "Hello world. How are you today?" } ``` #### 3. Flush Message ```json { "message-name": "flush" } ``` #### 4. Stop Message ```json { "message-name": "stop" } ``` #### 5. Finalize Message ```json { "message-name": "finalize-synthesis" } ``` ### Option 2: Text Message with Inline Flush #### 1. Start Message ```json { "message-name": "synthesize", "audio-format": "pcm", "voice-name": "Emily_Premium", "sample-rate": "24000", "volume": "1.0", "rate": "1.0", "Authorization": "" } ``` #### 2. Text Message with Inline Flush ```json { "message-name": "add-tts-text", "text": "Hello world. How are you today?", "flush": "true" } ``` #### 3. Stop Message ```json { "message-name": "stop" } ``` #### 4. Finalize Message ```json { "message-name": "finalize-synthesis" } ``` --- ## 10. Testing via Postman 1. Create a new **WebSocket Request** in Postman. 2. Enter the WebSocket URL using the following format: ```text wss:///synthesizer ``` 3. Connect to the WebSocket endpoint. 4. Send the `synthesize` message first. 5. Send the text to be synthesized using the `add-tts-text` message. 6. Send the `flush` message to trigger processing of the provided text. > This step can be skipped if the `add-tts-text` message includes the optional `flush` parameter. 7. Send the `stop` message if the synthesis process needs to be stopped. 8. Send the `finalize-synthesis` message to complete the synthesis flow. --- ## 11. Important Notes * Messages should only be sent after the WebSocket connection is successfully established. * The first message must be `synthesize`. * A valid access token must be provided in the `Authorization` field. * Access tokens should never be shared openly in documentation. * Environment-specific endpoint information should be replaced with placeholders such as ``. * The `voice-name` value must be one of the voices supported in the relevant environment. * `sample-rate`, `audio-format`, `volume`, and `rate` values must be compatible with the values supported by the service. * If the optional `flush` parameter is used in the `add-tts-text` message, a separate `flush` message is not required for that text input. * If the optional `flush` parameter is not used, the `flush` message should be sent separately after the text message.