---
title: "Set loudness, free for the first hour"
method: POST
path: "/api/try/loudness"
tags: ["Free API"]
---

# Set loudness, free for the first hour

`POST /api/try/loudness`

## Request

- Base URL: `https://audo.ai`
- URL: `https://audo.ai/api/try/loudness`
- Auth: one of:
  - none
  - HTTP bearer

Free for the first hour of the file, 10 times a day, without an account. With an API key (Authorization: Bearer <key>), the same request processes the whole file with credits ($0.01/min, 1 credits a minute; 1 credit is 1 US cent) when the balance covers it, and otherwise the free part. free=true always asks for the free part, and free=false always for the whole file. With exhausted quota, free=true returns 429; omitted free with insufficient balance returns 402. free=false with insufficient balance returns 402 with no fallback. Use an explicitly approved positive max_credits for paid automation. A request takes up to 100 MB of files either way (without a key, what its links fetch counts too), and links are fetched one at a time; upload a larger file in parts with POST /api/v1/files, then start the job with POST /api/v1/jobs. With an API key, an Idempotency-Key header makes a repeated request return the first one's job instead of starting another. Examples save unclassified response.body and response.headers: branch on HTTP status and Content-Type before naming media. See /docs/api#responses for the complete response client. Cut examples explicitly remove the named ranges; mode=keep retains them instead. The request waits up to about 30 seconds for the result. A job that takes longer, or a request with Prefer: respond-async, gets 202 with the job's link to check on. 

    curl -F file=@episode.wav -F target=podcast https://audo.ai/api/try/loudness -D response.headers -o response.body

## Headers

- `Prefer` string
- `Idempotency-Key` string

## Request body

- union
  - object
    - `url` string, uri, required: A public HTTPS link that Audo fetches
    - `file_token` string: Or the fileToken of an upload from POST /api/try/uploads
    - `target` 'podcast' | 'streaming' | 'broadcast' | 'audiobook' | 'custom': Where it's going: podcast (-16 LUFS), streaming (-14 LUFS), broadcast (-23 LUFS), audiobook (ACX checks), or custom (set custom_lufs). Default podcast.
    - `custom_lufs` number: The loudness for target custom, in LUFS (-30 to -5), such as -18.
    - `output_format` 'same' | 'wav' | 'mp3' | 'm4a' | 'flac': The result's format: same (as the input; a video stays a video), wav, mp3, m4a, or flac. Default same.
    - `max_credits` integer: With an API key only. The most this job may cost, in credits (1 credit is 1 US cent), such as 200. A job that would cost more doesn't start.
    - `free` boolean: With an API key only. true processes only the first hour, at no cost, a few times a day. false always processes the whole file with credits. Left out, the whole file when the balance covers it, otherwise the first hour free if quota is available (otherwise insufficient_balance / 402). true with exhausted quota returns free_limit_reached / 429; false with insufficient balance returns 402, without fallback.
  - object
    - `url` string, uri: A public HTTPS link that Audo fetches
    - `file_token` string, required: Or the fileToken of an upload from POST /api/try/uploads
    - `target` 'podcast' | 'streaming' | 'broadcast' | 'audiobook' | 'custom': Where it's going: podcast (-16 LUFS), streaming (-14 LUFS), broadcast (-23 LUFS), audiobook (ACX checks), or custom (set custom_lufs). Default podcast.
    - `custom_lufs` number: The loudness for target custom, in LUFS (-30 to -5), such as -18.
    - `output_format` 'same' | 'wav' | 'mp3' | 'm4a' | 'flac': The result's format: same (as the input; a video stays a video), wav, mp3, m4a, or flac. Default same.
    - `max_credits` integer: With an API key only. The most this job may cost, in credits (1 credit is 1 US cent), such as 200. A job that would cost more doesn't start.
    - `free` boolean: With an API key only. true processes only the first hour, at no cost, a few times a day. false always processes the whole file with credits. Left out, the whole file when the balance covers it, otherwise the first hour free if quota is available (otherwise insufficient_balance / 402). true with exhausted quota returns free_limit_reached / 429; false with insufficient balance returns 402, without fallback.

## Response `200`

The result file itself (beside it, details such as a time map stay in the job). A job with several audio or video outputs (such as a cut into separate parts) returns the job with download links instead

- object
  - `id` string, required
  - `tool` 'remove_noise' | 'enhance_voice' | 'transcribe_audio' | 'align_script' | 'cut_audio' | 'remove_silence' | 'adjust_loudness' | 'convert_audio' | 'join_audio' | 'replace_audio' | 'analyze_audio' | 'remove_fillers' | 'level_speakers' | 'mix_tracks', required
  - `status` 'queued' | 'running' | 'succeeded' | 'failed' | 'cancelled' | 'held', required
  - `progress` integer, required: How much of the job is done, from 0 to 100. It never goes down, and its first part is the time a job usually takes to start
  - `stage` 'queued' | 'preparing' | 'processing' | 'finishing' | 'succeeded' | 'failed' | 'cancelled' | 'held', required: Where the job is: queued (not started yet, perhaps behind the account's other running jobs), preparing (getting the file ready), processing (the tool's work), finishing (saving the result), then succeeded, failed, or cancelled; or held (waiting for payment: see finishUrl)
  - `estimatedSecondsLeft` integer, nullable, required: About how many seconds the job has left, from the file's length and how fast the tool runs, refined as it goes. A rough guide. Null while it's queued, while Audo is busy (waitingForWorker), and once it has ended
  - `waitingForWorker` boolean, required: True while a running job has waited in line longer than a start usually takes: Audo is busy, and the job carries on as soon as there's room. A free job also waits behind paid ones, so it can wait longer; jobs with credits go first
  - `inputFileIds` string[], required: The main input first
  - `outputFileIds` string[], required: The main output first, once the job succeeds
  - `free` boolean, required: A free job processes only the first part of its input, at no cost
  - `processedSeconds` number, required: How much of the input the job processes
  - `quotedCredits` integer, required
  - `chargedCredits` integer, nullable, required: Set when the job succeeds
  - `result` object, nullable, required: The tool's details, such as loudness before and after
  - `error` object, nullable, required
    - `code` string, required
    - `message` string, required
  - `createdAt` string, required: ISO 8601 time
  - `startedAt` string, nullable, required: ISO 8601 time
  - `finishedAt` string, nullable, required: ISO 8601 time
  - `finishUrl` string, nullable: For a free result cut short: the page where the whole file can run, as a new job. Null when the job did the whole file
  - `statusUrl` string, required: This job's capability link. GET it to check on the job; it works for 1 hour
  - `fullPriceCredits` integer, nullable, required: The price to process the whole input with credits
  - `outputs` object[], required: The outputs with download links, once the job succeeds
    - `fileId` string, required
    - `filename` string, required
    - `contentType` string, required
    - `sizeBytes` integer, nullable, required
    - `durationSeconds` number, nullable, required
    - `hasVideo` boolean, required
    - `url` string, required: A signed download link
    - `expiresAt` string, required: ISO 8601 time
    - `fileExpiresAt` string: When Audo deletes the file itself (the link above expires sooner)
  - `finishPriceCredits` integer, nullable: What the whole file costs in credits (1 credit is 1 cent)
  - `finishedBy` object, nullable: Once someone paid to finish this free run: the whole-file job
    - `jobId` string, required
    - `status` 'queued' | 'running' | 'succeeded' | 'failed' | 'cancelled' | 'held', required
    - `progress` integer, required
    - `statusUrl` string, required: The whole-file job's own status link. GET it until its status is succeeded, then download its outputs
  - `nextStep` string: What to do next, for an agent

## Other responses

- `202`: The job is still running. Check on it at the Location header's link
- `429`: Today's free uses are used up (or 3 runs already wait for payment from this address: rate_limited). The file is still taken and held for payment: details has finishUrl (where the whole file can run), finishPriceCredits, jobId, and statusUrl, whose finishedBy names the whole-file job once paid
- `default`: An error, with what went wrong and what to do next

---

[API](https://skmtc.dev/audo/apis/audo-api.md) · [All operations](https://skmtc.dev/audo/apis/audo-api/llms.txt) · [OpenAPI document](https://skmtc.dev/audo/apis/audo-api/revisions/0800e93224eb?raw)