Limits and errors | milliseconds.ai documentation

Limits

Limit	Value	What happens above it
Audio duration	60 minutes per call	`400 audio_too_long`. The API checks the duration before it transcribes
Request body	100 MB	`413` from the edge, before the API. That response is not the JSON error envelope
Speakers	4	Diarization labels at most four speakers
Client timeout	Allow 5 minutes	A long file can take more than a minute

Send compressed audio for long files. One hour of 16 kHz mono WAV is about 115 MB, over the body limit. The same hour as a 64 kbps mp3 is about 29 MB.

A rakeaudio call counts as one request against your requests-per-minute limit. See Limits and rate limits.

Errors

Errors use the standard envelope: { "error": { "code": "...", "message": "..." } }. See Errors.

Code	Status	Cause	What to do
`unsupported_media_type`	415	The `Content-Type` is not `audio/*` or `application/octet-stream`. A JSON body gets this error	Send the file bytes with an audio content type
`invalid_audio`	400	The body is empty, or the API cannot decode it as audio	Check the file. Do not retry the same bytes
`invalid_request`	400	`diarize` is not `true` or `false`	Fix the query parameter
`audio_too_long`	400	The audio is longer than 60 minutes	Split the file
`runner_error`	502	Transcription failed	Retry with backoff
`model_unavailable`	503	The model is not available	Retry later
`overloaded`	529	Every transcription slot stayed busy	Retry with backoff

These are real responses:

{"error":{"code":"unsupported_media_type","message":"Send the audio file as the raw body with content-type audio/* or application/octet-stream."}}
{"error":{"code":"invalid_audio","message":"The audio could not be decoded."}}

Authentication, rate-limit and credit errors (401, 403, 429) are the same for every model. See Errors.

Retries

Retry 502, 503 and 529 with exponential backoff, for example after 2, 4 and 8 seconds. A failed call is not billed. Never retry a 400 or a 415 with the same request: it fails again.