Websockets JSON

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Overview

In addition to a plaintext websocket implementation, Rime also has an implementation that sends and receives events as JSON objects. Like the other implementation, all synthesis arguments are provided as query parameters when establishing the connection.

The websocket API buffers inputs up to on of the following punctuation characters: ., ?, !. This is most pertinent for the initial messages sent to the API, as synthesis won’t begin until there are sufficient tokens to generate audio with natural prosody. After the first synthesis of any given utterance, typically enough time has elapsed that subsequent audio contains multiple clauses, and the buffering becomes largely invisible.

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Messages

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Send

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Text

This is the most common message, which contains text for synthesis.

schema:

type TextMessage = {
  text: string,
  contextId?: string,
}

examples:

{
    "text": "this is the minimum text message."
}

{
    "text": "this is a text message with a context id.",
    "contextId": "159495B1-5C81-4C73-A51A-9CE10A08239E"
}

Context IDs can be provided, which will be attached to subsequent messages that the server sends back to the client. Rime will not maintain multiple simultaneous context ids. The events will contain the most recent context ID at the time that audio was requested. In the above examples, even if both messages are received by the server before it sends any audio, the audio response for the first sentence will be tagged with contextId: null, and the audio for the second will be tagged with its UUID.

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Clear

Your client can clear out the accumulated buffer, which is useful in the case of interruptions.

{ "operation": "clear" }

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EOS

At times, your client would like to generate audio for whatever remains in the buffer, and then have the connection immediately closed.

{ "operation" : "eos" }

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Receive

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Chunk

The most common event will be the audio chunk.

type Base64String = string

type AudioChunkEvent = {
  type: "chunk",
  data: Base64String,
  contextId: string | null,
}

The audio will be a base64 encoded chunk of audio bytes in the audio format specified when the connection was established. If you provided any context id when sending the relevant text, it’ll be included here.

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Timestamps

Word timestamps are provided to better understand what precisely has been already said, in the event of an interruption.

type TimestampsEvent = {
  type: "timestamps",
  wordTimestamps: {
    words: string[],
    start: number[],
    end: number[],
  },
}

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Error

In the event of a malformed or unexpected input, the server will immediately respond with an error message. The server will not close the connection, and will still accept subsequent well-formed messages. It’s up to the client to decide if it wants to close upon receiving an error.

type ErrorEvent = {
  type: "error",
  message: string,
}

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Variable Parameters