Stream transcription

wss://api.typelessapi.com/v1/transcribe/stream WebSocket endpoint for streaming PCM audio; authentication and all options are passed as query parameters at handshake time.

Query parameters

token

string

required

Your API key. See Authentication.

model

string

required

Model tier. One of typeless-1.0-lite, typeless-1.0-pro, typeless-1.0-max. See Models & Pricing.

sample_rate

integer

default:"16000"

PCM sample rate in Hz. Allowed range: 8000–48000.

channels

integer

default:"1"

Number of audio channels. 1 or 2.

encoding

string

default:"pcm16"

Audio encoding. Only pcm16 (16-bit little-endian PCM) is supported.

language

string

Optional ISO 639-1 language hint. When omitted — or when an unsupported/unrecognized code is supplied — the language is detected automatically.

Client → server messages

Binary frames: send raw little-endian pcm16 audio bytes as WebSocket binary frames; the server buffers and processes them in the order received. keep_alive — resets the 60-second idle timer; does not extend the 10-second first-frame deadline.

{"type": "keep_alive"}

close_stream — signals no more audio; the server finalizes and returns the result.

{"type": "close_stream"}

Server → client messages

result — sent once after finalization; the server closes the connection immediately after.

{
  "type": "result",
  "status": "success",
  "result": {
    "transcript": "Let's move the launch to next Thursday and loop in the design team early.",
    "detected_language": "en",
    "duration_seconds": 42.5
  },
  "usage": {
    "billed_audio_seconds": 42.5,
    "output_token_count": 128
  },
  "request_id": "01JXXXXXXXXXXXXXXXXXXXXXXX"
}

error — sent when a fatal error occurs; after an error message the server closes the connection.

{
  "type": "error",
  "status": "error",
  "error": {
    "code": "SERVICE_UNAVAILABLE",
    "message": "Service temporarily unavailable"
  },
  "request_id": "01JXXXXXXXXXXXXXXXXXXXXXXX"
}

Timeouts

Timer	Value	Behavior
First audio frame	10 s from connect	Connection closes if no binary frame arrives; `keep_alive` does not extend this deadline
Idle	60 s	Reset by any audio frame or `keep_alive`; connection closes on expiry
Finalization	typically seconds, up to ~1 minute	After `close_stream`, the server drains remaining audio and refinement, then sends `result`

Connection close semantics

Normal: server sends result, then closes.
Error: server sends error, then closes.
Client disconnect: if transcription has already started, you are billed for the audio sent (15-second minimum).

Endpoint-specific errors

Code	When
`CONCURRENT_LIMIT_EXCEEDED`	Handshake rejected — too many open connections (429)
`INVALID_REQUEST`	Invalid handshake parameters, or missing/unknown `model`
`CLIENT_DISCONNECTED`	You disconnected mid-stream — recorded in usage logs, not sent as a message

See the full table in Errors.

Concurrency

Each account allows 10 concurrent connections by default; exceeding it fails the handshake with CONCURRENT_LIMIT_EXCEEDED — see Rate limits.

Reference

Endpoints

Limits & Errors

Query parameters

Client → server messages

Server → client messages

Timeouts

Connection close semantics

Endpoint-specific errors

Concurrency

​Query parameters

​Client → server messages

​Server → client messages

​Timeouts

​Connection close semantics

​Endpoint-specific errors

​Concurrency

Query parameters

Client → server messages

Server → client messages

Timeouts

Connection close semantics

Endpoint-specific errors

Concurrency