# mirelo-ai/sfx-1.6/extend-audio

> Mirelo SFX1.6 Extend Audio is a fast AI audio extension model that extends an audio prefix with seamless natural tails and optional ambience looping. Ready-to-use REST inference API for sound effects, ambient audio, game audio, video production, cinematic sound design, loopable audio assets, and professional audio generation workflows with simple integration, no coldstarts, and affordable pricing.

## Overview

- **Endpoint**: `https://api.wavespeed.ai/api/v3/mirelo-ai/sfx-1.6/extend-audio`
- **Polling/result URL**: `https://api.wavespeed.ai/api/v3/predictions/${PREDICTION_ID}/result`
- **Model ID**: `mirelo-ai/sfx-1.6/extend-audio`
- **Category**: audio-to-audio

## API Information

This model can be used via our HTTP API or more conveniently via our client libraries.
The API is asynchronous: submit a prediction, then poll its result URL until it completes.

### Input Schema

The API accepts the following input parameters:

- **`audio`** (`string`, _required_):
  Audio prefix to extend. Prefix duration must be 3 to 59 seconds, and total output is capped at 60 seconds.

- **`prompt`** (`string`, _optional_):
  Optional text prompt guiding the extension.

- **`append_duration`** (`number`, _optional_):
  Seconds to add after the prefix. Total output is capped at 60 seconds.
  - Default: `10`
  - Range: `1` to `57`

- **`ambience`** (`boolean`, _optional_):
  When true, extend and stitch the result so the tile loops seamlessly.
  - Default: `false`

- **`double_output`** (`boolean`, _optional_):
  Only used when ambience is true: concatenate the loop with itself for a 2x-length output.
  - Default: `false`

- **`num_samples`** (`integer`, _optional_):
  Number of variations to generate.
  - Default: `1`
  - Range: `1` to `4`



**Required Parameters Example**:

```json
{
  "audio": "https://interactive-examples.mdn.mozilla.net/media/cc0-audio/t-rex-roar.mp3"
}
```

**Full Example**:

```json
{
  "audio": "https://interactive-examples.mdn.mozilla.net/media/cc0-audio/t-rex-roar.mp3",
  "prompt": "A cinematic ocean wave at sunrise, highly detailed",
  "append_duration": 10,
  "ambience": false,
  "double_output": false,
  "num_samples": 1
}
```

### Result Data Schema

The `data` object returned by the API has the following fields:

- **`created_at`** (`string (date-time)`, _optional_):
  ISO timestamp of when the request was created (e.g., "2023-04-01T12:34:56.789Z").

- **`id`** (`string`, _optional_):
  Unique identifier for the prediction, the ID of the prediction to get.

- **`model`** (`string`, _optional_):
  Model ID used for the prediction.

- **`outputs`** (`array of string | object`, _optional_):
  Array of generated outputs (empty when status is not completed). Items are usually URL strings, but may be text strings or structured result objects, depending on the model.

- **`status`** (`string`, _optional_):
  Status of the task: created, processing, completed, or failed.

- **`urls`** (`object`, _optional_):
  Object containing related API endpoints.



**Example `data` Object**:

```json
{
  "created_at": "example",
  "id": "example",
  "model": "example",
  "outputs": [],
  "status": "example",
  "urls": {}
}
```

## Usage Examples

The examples use `jq` to read JSON. Set your API key first:

```bash
set -euo pipefail
export WAVESPEED_API_KEY="your-api-key"
```

### 1. Submit a prediction

```bash
REQUEST_BODY=$(cat <<'JSON'
{
  "audio": "https://interactive-examples.mdn.mozilla.net/media/cc0-audio/t-rex-roar.mp3"
}
JSON
)

SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  --request POST \
  --url https://api.wavespeed.ai/api/v3/mirelo-ai/sfx-1.6/extend-audio \
  --header "Authorization: Bearer ${WAVESPEED_API_KEY}" \
  --header "Content-Type: application/json" \
  --data "${REQUEST_BODY}")

printf '%s\n' "${SUBMIT_RESPONSE}" | jq .
```

The response contains the prediction ID in `data.id`.

### 2. Poll until complete and read `outputs`

```bash
PREDICTION_ID=$(printf '%s' "${SUBMIT_RESPONSE}" | jq -r '.data.id')
if [ -z "${PREDICTION_ID}" ] || [ "${PREDICTION_ID}" = "null" ]; then
  printf 'Submission response did not contain data.id\n' >&2
  exit 1
fi
RESULT_URL="https://api.wavespeed.ai/api/v3/predictions/${PREDICTION_ID}/result"

while true; do
  RESPONSE=$(curl --silent --show-error --fail-with-body \
    --request GET \
    --url "${RESULT_URL}" \
    --header "Authorization: Bearer ${WAVESPEED_API_KEY}")

  RESULT=$(printf '%s' "${RESPONSE}" | jq -e '.data')
  STATUS=$(printf '%s' "${RESULT}" | jq -er '.status')
  case "${STATUS}" in
    completed)
      # Generated files are returned in the outputs array.
      printf '%s\n' "${RESULT}" | jq '.outputs'
      break
      ;;
    failed|cancelled|timeout|deleted)
      printf '%s\n' "${RESULT}" | jq '{status, error, code}'
      exit 1
      ;;
    *)
      sleep 2
      ;;
  esac
done
```

## Additional Resources

### Documentation

- [Model Playground](https://wavespeed.ai/models/mirelo-ai/sfx-1.6/extend-audio)
- [API Documentation](https://wavespeed.ai/docs/docs-api/mirelo-ai/mirelo-ai-sfx-1.6-extend-audio)