Limits

The bounds a session is admitted and held under, and what the service does when one is reached.

API access is not open yet. It is opening gradually; join the waitlist.

Audio format

Audio is 16 kHz, mono, signed 16-bit little-endian PCM. The protocol_version is "1.0".

Session bounds

• DICON_MAX_AUDIO_SECONDS — 3600 — the most audio one session accepts.
• DICON_MAX_CHUNK_SECONDS — 2 — the most audio one message may carry.
• DICON_MAX_QUEUED_AUDIO_SECONDS — 8 — the most audio that may be outstanding before the server applies backpressure.
• DICON_MAX_ENROLLMENT_SECONDS — 12 — target-speaker enrollment audio. Send the full 12 seconds: a shorter enrollment falls short of a prefill threshold inside the diarizer and costs more to set up, not less, so it is not a way to save time.
• DICON_IDLE_TIMEOUT_SECONDS — 30 — how long a session may sit without audio before it is ended.

These are the shipped defaults. An operator configures them independently, so a deployment may differ. Separately, and not operator-configurable, the server holds at most 128 undelivered events per session; a client that stops reading is subject to the backpressure described on the errors page.

Request fields

• expected_num_speakers is "auto" or an integer from 1 to 4. Four is the ceiling: the diarizer has exactly four speaker slots, and there is no larger one.
• client_request_id is optional, 1 to 128 characters, matching ^[A-Za-z0-9._:-]+$.

Quotas

A quota is expressed in audio seconds and is checked when a session is admitted, not continuously. A session that was admitted runs to its own end, so a caller can finish slightly past a quota boundary. This is deliberate: refusing mid-stream would end an established session.

Consumption is written back when a session ends. Billing counts audio the service processed, not audio submitted.

A key with no quota set is unlimited, not zero. A key with no scopes set is unrestricted, not unauthorized.

Exceeding a quota is quota_exhausted, and it is not retryable — retrying will not succeed until more quota exists.

When a limit is reached

• not_ready — retryable; the worker has not finished loading.
• overload — retryable; an admission ceiling was reached. Back off and retry.
• quota_exhausted — not retryable.
• validation — not retryable; the request was malformed.
• unauthorized — not retryable; the credential was missing or rejected.
• forbidden — not retryable; the credential lacks the required scope.
• not_found — not retryable; no such session.

The errors page covers ordering and cancellation behaviour; the authentication page covers credentials.