Stream speech

wss://sabi-tts.dev.neuralace.co/v1/audio/speech/stream

The streaming endpoint synthesizes audio one sentence at a time and sends each sentence as a binary WebSocket frame as soon as it is ready. Begin playback on the first frame for the lowest perceived latency — ideal for conversational agents.

Protocol

Connect

Open a WebSocket to /v1/audio/speech/stream with your key in the header: Authorization: Bearer sk_….

Start a session

Send a start control frame (JSON text frame):

{ "type": "start", "voice": "capella", "response_format": "wav" }

The server replies with { "type": "ready" } once the session is open.

Send text

After ready, send one or more text frames, then a done frame:

{ "type": "text", "text": "Hello. This streams sentence by sentence." }

{ "type": "done" }

Receive audio

The server sends binary frames — one complete audio buffer per sentence — followed by { "type": "session.done" } when synthesis is finished.

Frame reference

Client → server

Frame	Purpose
`{"type":"start","voice":…,"response_format":…}`	Opens the session. Must be the first frame.
`{"type":"text","text":…}`	Text to synthesize (metered per character).
`{"type":"done"}`	No more text; finish and close the session.

Server → client

Frame	Purpose
`{"type":"ready"}`	Session open — safe to send `text` frames.
binary frame	One sentence of audio in the requested `response_format`.
`{"type":"session.done"}`	All audio delivered.
`{"type":"error","message":…}`	Something went wrong (bad frame, quota, upstream error).

Send the start frame before anything else — text frames sent first are rejected with an error frame. Quota and rate limits apply per text frame, the same as HTTP requests.

Example

Python

# pip install websockets
import asyncio, json, os, websockets

async def main():
    url = "wss://sabi-tts.dev.neuralace.co/v1/audio/speech/stream"
    headers = [("Authorization", "Bearer " + os.environ["SABI_API_KEY"])]
    async with websockets.connect(url, additional_headers=headers, max_size=64 * 1024 * 1024) as ws:
        await ws.send(json.dumps({"type": "start", "voice": "capella", "response_format": "wav"}))
        idx = 0
        async for msg in ws:
            if isinstance(msg, (bytes, bytearray)):       # per-sentence audio frame
                open(f"sentence_{idx}.wav", "wb").write(msg); idx += 1
                continue
            evt = json.loads(msg)
            if evt["type"] == "ready":
                await ws.send(json.dumps({"type": "text", "text": "Hello. This streams sentence by sentence."}))
                await ws.send(json.dumps({"type": "done"}))
            elif evt["type"] == "session.done":
                break

asyncio.run(main())

Get started

Capella

API reference

Protocol

Frame reference

Client → server

Server → client

Example

​Protocol

​Frame reference

​Client → server

​Server → client

​Example

Protocol

Frame reference

Client → server

Server → client

Example