Name: ACE-Step 1.5 API: AI Music and Song Generator
Brand: magicapi
SKU: api-magicapi-music-generation-api-fishaudio-ace-step-1-5
Availability: InStock
Author: API Market

Shashank Agarwal

# 🎵 Music Generator API (ACE Studio ACE-Step 1.5)

## Overview
ACE-Step 1.5 is an open source music generation model. Describe the genre, mood and instruments in `prompt`, add `lyrics` for a song or keep `[Instrumental]` for an instrumental track, and the model returns one audio file per song.

You can set the length (`duration`, up to 600 seconds), tempo (`bpm`), key (`key_scale`) and time signature, or leave them to automatic detection. `batch_size` generates up to 4 songs in one request.

## Features
- **Text to music**: describe the style in `prompt` (up to 512 characters).
- **Lyrics or instrumental**: send `lyrics` (up to 4096 characters) or `[Instrumental]` (default).
- **Length**: `duration` from 1 to 600 seconds, or `-1` for automatic (default `30`).
- **Musical controls**: `bpm` (30 to 300), `key_scale` (for example `F# minor`) and `time_signature` (`2`, `3`, `4`, `6` or `auto`).
- **Several songs per request**: `batch_size` from 1 to 4.
- **Output formats**: `mp3` (default), `wav`, `flac`, `wav32`, `opus` and `aac`.
- **Planning step**: `thinking` (default `true`) lets the language model reason about metadata, caption and language before generating.

## Use Cases
1. **Background music**: tracks for videos, podcasts, games and apps.
2. **Song drafts**: hear lyrics as a song in a chosen style.
3. **Variations**: several takes of the same idea with `batch_size`.
4. **Music apps**: let users create tracks from a short description.

## Visual Examples
### Example Input
Prompt: "upbeat electronic dance music with heavy bass and synth leads"

Other fields: `lyrics` `[Instrumental]`, `duration` `30`, `batch_size` `1`, `audio_format` `mp3`, `inference_steps` `8`, `guidance_scale` `7`, `shift` `3`, `thinking` `true`, `time_signature` `auto`, empty `key_scale`, `seed` `-1`.

### Example Output
[Watch the example output](https://blog.api.market/wp-content/uploads/2026/10/ace-step-1-5-output-27t37hev-api-market.mp3)

## Input Parameters
| Field | Type | Required | Default | Allowed values | Description |
| --- | --- | --- | --- | --- | --- |
| `prompt` | string | No | `upbeat electronic dance music with heavy bass and synth leads` |  | Short text describing the music: genre, mood, instruments, style. Max 512 characters |
| `lyrics` | string | No | `[Instrumental]` |  | Lyrics for the song. Use `[Instrumental]` for an instrumental track. Max 4096 characters |
| `duration` | number | No | `30` | -1 to 600 | Target audio length in seconds. Set to -1 for automatic |
| `bpm` | integer | No | none | 30 to 300 | Beats per minute (30 to 300). Leave unset for automatic |
| `key_scale` | string | No | `""` |  | Musical key and scale, for example 'C major', 'F# minor' or 'Bb major'. Leave empty for automatic |
| `time_signature` | string | No | `auto` | `auto`, `2`, `3`, `4`, `6` | Time signature: 2 for 2/4, 3 for 3/4, 4 for 4/4, 6 for 6/8. `auto` detects it |
| `inference_steps` | integer | No | `8` | 1 to 200 | Number of diffusion steps. Turbo model: 4 to 8 recommended; base or SFT models: 32 to 100 |
| `guidance_scale` | number | No | `7` | 1 to 15 | Guidance strength. Only used by base or SFT models and ignored by turbo; higher values follow the prompt more strictly |
| `shift` | number | No | `3` | 1 to 5 | Timestep shift factor; 3.0 suits the turbo model |
| `seed` | integer | No | `-1` |  | Random seed for reproducibility. -1 for random |
| `thinking` | boolean | No | `true` |  | Let the language model reason about metadata, caption and language detection before generating |
| `batch_size` | integer | No | `1` | 1 to 4 | Number of songs to generate in parallel |
| `audio_format` | string | No | `mp3` | `mp3`, `wav`, `flac`, `wav32`, `opus`, `aac` | Output audio format |

## Pricing
- **Pay As You Go (PAYG) pricing**: you only pay for what you use.
- **Price**: $0.12 per API unit.
- **1 API unit = 1 request with up to 110 seconds of processing.** A request that takes longer uses one unit per started block of 110 seconds (for example, 275 seconds of processing uses 3 units, $0.36).
- Longer `duration`, larger `batch_size` and more `inference_steps` take longer and can use more units.
- **Example cost**: the example request took 9.0 seconds of processing, which is 1 unit, $0.12.
- **Failed or cancelled predictions are not billed.**
- **GET requests to check prediction status** are free and don't count toward API unit usage.
- **No monthly subscription fee.**

## API Documentation

### Base URL
All API requests go to: `https://prod.api.market/api/v1/magicapi/music-generation-api-fishaudio-ace-step-1-5`

### Authentication
Send your api.market API key in the `x-api-market-key` header:
```
x-api-market-key: YOUR_API_MARKET_KEY
```

### Asynchronous Processing
**IMPORTANT**: This API is asynchronous. The flow is:
1. Send a POST request to `/predictions`. A successful request returns **201 Created** with a prediction `id` and a `status` of `starting` or `processing`.
2. Poll GET `/predictions/{id}` with that ID.
3. Keep polling while `status` is `starting` or `processing`.
4. Stop when `status` is `succeeded` (read `output`), `failed` or `canceled` (read `error`).

A polling interval of 1 second and an overall timeout of 600 seconds (10 minutes) work well.

### Endpoints

#### Create a Prediction
```bash
curl -X POST "https://prod.api.market/api/v1/magicapi/music-generation-api-fishaudio-ace-step-1-5/predictions" \
  -H "Content-Type: application/json" \
  -H "x-api-market-key: YOUR_API_MARKET_KEY" \
  -d '{
    "version": "74e3a7d383b18815e277de5223f5fe9d53d38832de15aa567fe729fa129d0d85",
    "input": {
      "seed": -1,
      "shift": 3,
      "lyrics": "[Instrumental]",
      "prompt": "upbeat electronic dance music with heavy bass and synth leads",
      "duration": 30,
      "thinking": true,
      "key_scale": "",
      "batch_size": 1,
      "audio_format": "mp3",
      "guidance_scale": 7,
      "time_signature": "auto",
      "inference_steps": 8
    }
  }'
```

Response (201 Created):
```json
{
  "id": "27t37hevr1rmw0d1d0xshdxr2g",
  "version": "74e3a7d383b18815e277de5223f5fe9d53d38832de15aa567fe729fa129d0d85",
  "status": "starting",
  "created_at": "2026-10-23T10:08:35.937Z"
}
```

#### Check Prediction Status
```bash
curl -X GET "https://prod.api.market/api/v1/magicapi/music-generation-api-fishaudio-ace-step-1-5/predictions/{id}" \
  -H "x-api-market-key: YOUR_API_MARKET_KEY"
```

Response when the prediction has finished (200 OK):
```json
{
  "id": "27t37hevr1rmw0d1d0xshdxr2g",
  "status": "succeeded",
  "output": [
    "https://blog.api.market/wp-content/uploads/2026/10/ace-step-1-5-output-27t37hev-api-market.mp3"
  ],
  "error": null,
  "created_at": "2026-10-23T10:08:35.937Z",
  "started_at": "2026-10-23T10:09:54.099Z",
  "completed_at": "2026-10-23T10:10:03.068Z"
}
```

`output` is a list of audio file URLs, one per song (`batch_size`).

### Status Codes
- **201 Created**: prediction created (POST `/predictions`). This is the normal success response.
- **200 OK**: prediction details returned (GET `/predictions/{id}`).
- **400 Bad Request**: invalid input, for example a `duration` above 600, a `batch_size` above 4 or an `audio_format` that is not in the list.
- **401 Unauthorized**: missing or invalid API key.
- **404 Not Found**: no prediction with that ID.
- **429 Too Many Requests**: rate limit exceeded.
- **500 Internal Server Error** or **503 Service Unavailable**: temporary server problem; retry later.

## Rate Limits
All plans allow 10 requests per second. Requests above that return `429 Too Many Requests`; back off before retrying and honour any `Retry-After` header. Polling a prediction with GET is free but still counts toward the per-second limit, so poll every 1 to 5 seconds rather than in a tight loop.

## Error Handling
- Check the HTTP status code of every request and read the response body for the error message.
- A prediction can also end with `status` set to `failed`; the `error` field then explains why. Failed predictions are not billed.
- Retry 429, 500 and 503 responses with exponential backoff. Fix the input before retrying a 400.

## Implementation Guide
### Example Code

#### JavaScript
```javascript
const apiKey = "YOUR_API_MARKET_KEY";
const baseUrl = "https://prod.api.market/api/v1/magicapi/music-generation-api-fishaudio-ace-step-1-5";

async function createAndWaitForPrediction(input) {
  const response = await fetch(`${baseUrl}/predictions`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "x-api-market-key": apiKey
    },
    body: JSON.stringify({ version: "74e3a7d383b18815e277de5223f5fe9d53d38832de15aa567fe729fa129d0d85", input })
  });

  if (response.status !== 201) {
    throw new Error(`API error: ${response.status} ${await response.text()}`);
  }

  const prediction = await response.json();
  return pollForResults(prediction.id);
}

const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

async function pollForResults(predictionId) {
  const maxTimeout = 600000;
  const pollInterval = 1000;
  const startTime = Date.now();

  while (Date.now() - startTime < maxTimeout) {
    const response = await fetch(`${baseUrl}/predictions/${predictionId}`, {
      headers: { "x-api-market-key": apiKey }
    });

    if (!response.ok) {
      throw new Error(`API error: ${response.status} ${await response.text()}`);
    }

    const prediction = await response.json();

    if (prediction.status === "succeeded") {
      return prediction.output;
    }

    if (prediction.status === "failed" || prediction.status === "canceled") {
      throw new Error(`Prediction ${prediction.status}: ${prediction.error || "Unknown error"}`);
    }

    await delay(pollInterval);
  }

  throw new Error("Prediction timed out after 10 minutes");
}

createAndWaitForPrediction({
  "seed": -1,
  "shift": 3,
  "lyrics": "[Instrumental]",
  "prompt": "upbeat electronic dance music with heavy bass and synth leads",
  "duration": 30,
  "thinking": true,
  "key_scale": "",
  "batch_size": 1,
  "audio_format": "mp3",
  "guidance_scale": 7,
  "time_signature": "auto",
  "inference_steps": 8
}).then((output) => console.log(output));
```

#### Python
```python
import time
import requests

API_KEY = "YOUR_API_MARKET_KEY"
BASE_URL = "https://prod.api.market/api/v1/magicapi/music-generation-api-fishaudio-ace-step-1-5"


def create_and_wait_for_prediction(input_data):
    headers = {"Content-Type": "application/json", "x-api-market-key": API_KEY}
    response = requests.post(
        f"{BASE_URL}/predictions",
        headers=headers,
        json={"version": "74e3a7d383b18815e277de5223f5fe9d53d38832de15aa567fe729fa129d0d85", "input": input_data},
    )

    if response.status_code != 201:
        raise Exception(f"API error: {response.status_code} {response.text}")

    return poll_for_results(response.json()["id"])


def poll_for_results(prediction_id):
    max_timeout = 600
    poll_interval = 1
    headers = {"x-api-market-key": API_KEY}
    start_time = time.time()

    while time.time() - start_time < max_timeout:
        response = requests.get(f"{BASE_URL}/predictions/{prediction_id}", headers=headers)

        if response.status_code != 200:
            raise Exception(f"API error: {response.status_code} {response.text}")

        prediction = response.json()

        if prediction["status"] == "succeeded":
            return prediction["output"]

        if prediction["status"] in ("failed", "canceled"):
            raise Exception(f"Prediction {prediction['status']}: {prediction.get('error') or 'Unknown error'}")

        time.sleep(poll_interval)

    raise Exception("Prediction timed out after 10 minutes")


output = create_and_wait_for_prediction({
    "seed": -1,
    "shift": 3,
    "lyrics": "[Instrumental]",
    "prompt": "upbeat electronic dance music with heavy bass and synth leads",
    "duration": 30,
    "thinking": True,
    "key_scale": "",
    "batch_size": 1,
    "audio_format": "mp3",
    "guidance_scale": 7,
    "time_signature": "auto",
    "inference_steps": 8
})
print(output)
```

## FAQ
- **How do I make an instrumental track?**
  - Keep `lyrics` at `[Instrumental]` (the default) and describe the music in `prompt`.
- **How long can a track be?**
  - Up to 600 seconds, set with `duration`. Use `-1` to let the model choose.
- **Can I fix the tempo and key?**
  - Yes. Set `bpm` (30 to 300) and `key_scale`, for example `C major`. Leave them unset or empty for automatic choices.
- **How do I get several versions at once?**
  - Set `batch_size` up to 4. You get one URL per song in `output`.
- **What does one request cost?**
  - One unit ($0.12) covers up to 110 seconds of processing. The example (one 30-second track) took 9.0 seconds, so it cost $0.12.

## Contact Us
If you have any questions, reach out to us through the chat on the bottom right of the page. You can also email our support team at hello@magicapi.com.


Generate music from a text description with ACE-Step 1.5: instrumentals or songs with your lyrics, with length, tempo, key and format controls. Pay per request.