# ACE Step Audio Outpaint API

> 기존 오디오 클립의 시작 전이나 끝난 후에 새로 작곡한 음악을 추가합니다

`audio_url`로 제공된 트랙을 이어갑니다. `extend_before_duration`과 `extend_after_duration`은 시작 또는 끝에 각각 최대 107초를 추가하며, 기본값은 뒤쪽 30초입니다. 스타일은 `tags`에서 가져오고, 추가된 부분에 사용할 `lyrics`를 선택적으로 지정할 수 있습니다. 스텝 수, 스케줄러 및 가이던스 설정은 다른 ACE Step 모델과 같습니다.

- 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/ko/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 |  |  | 아웃페인팅에 사용할 오디오 파일 URL입니다. |
| `extend_before_duration` |  | number | no | `0` | 0 – 107 | 오디오 시작 전 확장 길이(초)입니다. |
| `extend_after_duration` |  | number | no | `30` | 0 – 107 | 오디오 끝 후 확장 길이(초)입니다. |
| `tags` |  | string | yes |  |  | 쉼표로 구분된 장르의 오디오 스타일 태그입니다. 태그를 제공하는 다른 방법으로 `prompt`를 사용할 수 있습니다. |
| `lyrics` |  | string | no | `` |  | [verse], [chorus], [bridge] 같은 컨트롤로 곡의 구간을 구성한 가사입니다. 가사가 없는 오디오는 이 입력을 생략하거나 [inst] 또는 [instrumental]만 제공하세요. |
| `number_of_steps` |  | integer | no | `27` | 3 – 60 | 오디오 생성에 사용되는 단계 수입니다. |
| `seed` |  | integer \| null | no |  |  | 재현 가능한 생성을 위한 시드입니다. 값을 제공하지 않으면 무작위로 선택됩니다. |
| `scheduler` |  | enum (string) | no | `euler` | `euler`, `heun` | 생성 중 사용할 스케줄러입니다. |
| `guidance_type` |  | enum (string) | no | `apg` | `cfg`, `apg`, `cfg_star` | 생성 중 사용할 CFG 유형입니다. |
| `granularity_scale` |  | integer | no | `10` | -100 – 100 | 생성 중 적용되는 세부 수준입니다. 높이면 아티팩트가 줄어들 수 있습니다. |
| `guidance_interval` |  | number | no | `0.5` | 0 – 1 | 가이드가 적용되는 생성 스케줄의 구간입니다. 0.5를 선택하면 0.25 * infer_steps부터 0.75 * infer_steps까지의 단계로 제한되며, 시작과 끝에는 가이드가 적용되지 않습니다. |
| `guidance_interval_decay` |  | number | no | `0` | 0 – 1 | 생성 구간 내 가이드 감쇠입니다. 0.0은 감쇠를 비활성화하고, 그 외의 값은 해당 구간에서 guidance_scale을 min_guidance_scale까지 감소시킵니다. |
| `guidance_scale` |  | number | no | `15` | 0 – 200 | 생성 중 적용되는 가이드 강도입니다. |
| `minimum_guidance_scale` |  | number | no | `3` | 0 – 200 | 생성 중 감쇠 후 도달하는 최저 가이드 강도입니다. |
| `tag_guidance_scale` |  | number | no | `5` | 0 – 10 | 생성 중 적용되는 태그 가이드 강도입니다. |
| `lyric_guidance_scale` |  | number | no | `1.5` | 0 – 10 | 생성 중 적용되는 가사 가이드 강도입니다. |

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} | 생성으로 만들어진 오디오 파일입니다. |
| `seed` | integer | 생성에 사용된 무작위 시드입니다. |
| `tags` | string | 생성 중 적용된 장르 태그입니다. |
| `lyrics` | string | 생성 중 적용된 가사입니다. |

## 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