# ACE Step Audio Outpaint API

> Forlænger et eksisterende lydklip før begyndelsen eller efter slutningen med nykomponeret musik

Fortsætter et track leveret via `audio_url`. `extend_before_duration` og `extend_after_duration` tilføjer hver op til 107 sekunder i begyndelsen eller slutningen, og standarden er 30 sekunder efter. Stilen kommer fra `tags`, med valgfri `lyrics` til de tilføjede dele. Antal steps, scheduler og guidance-indstillinger svarer til de andre ACE Step-modeller.

- Model id: `ace-step/audio-outpaint`
- Made by: ACE Studio
- Category: Text to Music
- Output: audio
- Price per second of your output audio: $0.0002 / second of output audio (cheapest run $0.001 (1 API credit))
- Run: `POST https://api.doitong.com/v1/run/ace-step/audio-outpaint`
- Quote: `POST https://api.doitong.com/v1/quote/ace-step/audio-outpaint`
- Docs page: https://doitong.com/da/developers/models/ace-step/audio-outpaint

## Pricing

Price: **$0.0002 / second of output audio**. Price per second of your output audio: the input files are measured before the run (length, resolution, frame rate). The quote measures the same files and is exactly what the run charges.

The full example input below costs $0.006 = 6 API credits (30 s output audio × $0.0002).

Prices are the upstream price in USD, paid from the API balance in API credits (1000 API credits = 1 USD). `POST https://api.doitong.com/v1/quote/ace-step/audio-outpaint` with the same JSON body returns the exact price for that input; the quote is exactly what a run charges. Invalid input is never charged and failed or canceled requests are refunded automatically.

## Input parameters

Send either the canonical name or the native field name (not both). Canonical names are the same across models.

| Parameter | Canonical name | Type | Required | Default | Allowed values / range | Description |
|---|---|---|---|---|---|---|
| `audio_url` | `audio` | string (audio URL) | yes |  |  | URL til lydfil til outpainting. |
| `extend_before_duration` |  | number | no | `0` | 0 – 107 | Længden af udvidelsen før lydens begyndelse, i sekund. |
| `extend_after_duration` |  | number | no | `30` | 0 – 107 | Længden af udvidelsen efter lydens slutning, i sekund. |
| `tags` |  | string | yes |  |  | Lydstil-tags angivet som kommaseparerede genrer, med `prompt` som alternativ måde at angive dem på. |
| `lyrics` |  | string | no | `` |  | Sungne sangtekster, hvor sangsektioner organiseres med kontroller som [verse], [chorus] og [bridge]. For lyd uden sungne sangtekster skal dette input udelades eller kun indeholde [inst] eller [instrumental]. |
| `number_of_steps` |  | integer | no | `27` | 3 – 60 | Antal trin brugt under lydgenerering. |
| `seed` |  | integer \| null | no |  |  | Seed til reproducerbar generering, valgt tilfældigt, medmindre du angiver en værdi. |
| `scheduler` |  | enum (string) | no | `euler` | `euler`, `heun` | Scheduler brugt under generering. |
| `guidance_type` |  | enum (string) | no | `apg` | `cfg`, `apg`, `cfg_star` | CFG-type brugt under generering. |
| `granularity_scale` |  | integer | no | `10` | -100 – 100 | Granularitetsskala anvendt under generering. En forøgelse kan reducere artefakter. |
| `guidance_interval` |  | number | no | `0.5` | 0 – 1 | Den del af genereringsplanen, der modtager vejledning: valg af 0.5 begrænser den til trin fra 0.25 * infer_steps til 0.75 * infer_steps, så begyndelsen og slutningen ikke modtager vejledning. |
| `guidance_interval_decay` |  | number | no | `0` | 0 – 1 | Vejledningshenfald inden for genereringsintervallet: 0.0 holder henfald deaktiveret; ellers falder skalaen i intervallet fra guidance_scale til min_guidance_scale. |
| `guidance_scale` |  | number | no | `15` | 0 – 200 | Skala for vejledning anvendt under generering. |
| `minimum_guidance_scale` |  | number | no | `3` | 0 – 200 | Laveste vejledningsskala efter henfald under generering. |
| `tag_guidance_scale` |  | number | no | `5` | 0 – 10 | Skala for tagvejledning anvendt under generering. |
| `lyric_guidance_scale` |  | number | no | `1.5` | 0 – 10 | Skala for sangtekstvejledning anvendt under generering. |

File parameters (`audio`) take a public `https://` URL, a `data:` URI up to 10 MB, or the `file_url` of an upload from `POST /files`.

## Example input

Required parameters only:

```json
{
  "tags": "lofi, hiphop, drum and bass, trap, chill",
  "audio": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3"
}
```

A fuller example:

```json
{
  "tags": "lofi, hiphop, drum and bass, trap, chill",
  "audio_url": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3"
}
```

## Run it

Set `DOITONG_API_KEY` to a key from https://doitong.com/developers/dashboard#keys. `?wait=20` returns the finished request in the same call when it is ready within 20 seconds; otherwise poll `GET /requests/{id}` (it also accepts `?wait=`), or pass `webhook_url`.

### curl

```bash
# Run the model; wait up to 20 s for the finished result in the same call
curl -X POST "https://api.doitong.com/v1/run/ace-step/audio-outpaint?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "tags": "lofi, hiphop, drum and bass, trap, chill",
    "audio_url": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3"
  }'

# Still "queued" or "running"? Poll with the id from the response:
curl "https://api.doitong.com/v1/requests/REQUEST_ID?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY"
```

### JavaScript

```javascript
const API = "https://api.doitong.com/v1";
const headers = {
  "Authorization": "Bearer " + process.env.DOITONG_API_KEY,
  "Content-Type": "application/json",
};

// Run the model; wait up to 20 s for the finished result in the same call
let res = await fetch(API + "/run/ace-step/audio-outpaint?wait=20", {
  method: "POST",
  headers,
  body: JSON.stringify({
    "tags": "lofi, hiphop, drum and bass, trap, chill",
    "audio_url": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3"
  }),
});
let request = await res.json();
if (!res.ok) throw new Error(request.error.code + ": " + request.error.message);

// Not finished yet: long-poll until it is
while (request.status === "queued" || request.status === "running") {
  res = await fetch(API + "/requests/" + request.id + "?wait=20", { headers });
  request = await res.json();
}
if (request.status !== "succeeded") throw new Error(JSON.stringify(request.error));
console.log(request.outputs.map((o) => o.url), request.cost.credits + " API credits ($" + request.cost.usd + ")");
```

### Python

```python
import os
import requests

API = "https://api.doitong.com/v1"
headers = {"Authorization": "Bearer " + os.environ["DOITONG_API_KEY"]}

payload = {
    "tags": "lofi, hiphop, drum and bass, trap, chill",
    "audio_url": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3",
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/ace-step/audio-outpaint", params={"wait": 20}, json=payload, headers=headers)
request = r.json()
if not r.ok:
    raise RuntimeError(request["error"]["code"] + ": " + request["error"]["message"])

# Not finished yet: long-poll until it is
while request["status"] in ("queued", "running"):
    request = requests.get(API + "/requests/" + request["id"], params={"wait": 20}, headers=headers).json()
if request["status"] != "succeeded":
    raise RuntimeError(request["error"])
print([o["url"] for o in request["outputs"]], request["cost"]["credits"], "API credits", "$" + request["cost"]["usd"])
```

### MCP

The MCP server at `https://api.doitong.com/v1/mcp` exposes the tools `search_models`, `get_model`, `quote`, `run`, `get_request`, `cancel_request`, `list_requests`, `create_upload` and `get_account`. A `run` call for this model:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "run",
    "arguments": {
      "model_id": "ace-step/audio-outpaint",
      "input": {
        "tags": "lofi, hiphop, drum and bass, trap, chill",
        "audio_url": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3"
      },
      "wait_seconds": 20
    }
  }
}
```

## Response

Every call returns a request object. `status` is one of `queued`, `running`, `succeeded`, `failed`, `canceled`. `outputs` lists the generated files with URLs on our storage (kept forever, or 7 days with `?storage=temporary`; `storage` says which); `output` is the model's own result object with the same URLs.

```json
{
  "id": "req_8k2m4q7x1z9c3v5b6n0p2r4t",
  "object": "request",
  "model": "ace-step/audio-outpaint",
  "status": "succeeded",
  "created_at": "2026-10-20T12:00:00Z",
  "started_at": "2026-10-20T12:00:02Z",
  "completed_at": "2026-10-20T12:00:09Z",
  "queue_position": null,
  "cost": {
    "credits": 6,
    "usd": "0.006",
    "charged": 6,
    "refunded": 0
  },
  "input": {
    "tags": "lofi, hiphop, drum and bass, trap, chill",
    "audio_url": "https://content.doitong.com/audio/showcase/v3/tools/dub_es.mp3"
  },
  "output": {
    "audio": {
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp3",
      "content_type": "audio/mpeg",
      "file_name": "0-output.mp3",
      "file_size": 1843200
    },
    "seed": 42,
    "tags": "lofi, hiphop, drum and bass, trap, chill",
    "lyrics": "[inst]"
  },
  "outputs": [
    {
      "type": "audio",
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp3",
      "content_type": "audio/mpeg",
      "file_size": 1843200,
      "duration": 12,
      "stored": true
    }
  ],
  "error": null,
  "metrics": {
    "inference_seconds": 6.8
  },
  "urls": {
    "self": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `audio` | object {url, content_type, file_name, file_size} | Lydfil produceret ved generering. |
| `seed` | integer | Tilfældig seed brugt under generering. |
| `tags` | string | Genre-tags anvendt under generering. |
| `lyrics` | string | Sangtekster anvendt under generering. |

## Related models

- [ACE Step](https://doitong.com/developers/models/ace-step.md) (`ace-step`): $0.0002 / second
- [ACE Step Audio Inpaint](https://doitong.com/developers/models/ace-step/audio-inpaint.md) (`ace-step/audio-inpaint`): $0.0002 / second of input audio
- [ACE Step Audio To Audio](https://doitong.com/developers/models/ace-step/audio-to-audio.md) (`ace-step/audio-to-audio`): $0.0002 / second of input audio
- [ACE Step Prompt To Audio](https://doitong.com/developers/models/ace-step/prompt-to-audio.md) (`ace-step/prompt-to-audio`): $0.0002 / second
- [MiniMax Music 3](https://doitong.com/developers/models/minimax/music-3.md) (`minimax/music-3`): $0.002 / second
- [DiffRhythm: Lyrics to Song](https://doitong.com/developers/models/diffrhythm.md) (`diffrhythm`): $0.001 / second
- [Elevenlabs Music](https://doitong.com/developers/models/elevenlabs/music.md) (`elevenlabs/music`): $0.60 / minute of output audio
- [Elevenlabs Music v2](https://doitong.com/developers/models/elevenlabs/music/v2.md) (`elevenlabs/music/v2`): $0.60 / minute of output audio

## Links

- HTML page: https://doitong.com/developers/models/ace-step/audio-outpaint
- All models and guides for AI agents: https://doitong.com/developers/llms.txt
- OpenAPI 3.1 with this model's typed request body: https://doitong.com/developers/openapi.json?model=ace-step/audio-outpaint
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/ace-step/audio-outpaint