Sfx 1.6 Extend Audio | AI Voice Conversion API

Mirelo AI SFX 1.6 Extend Audio

Mirelo AI SFX 1.6 Extend Audio extends an existing audio clip by generating new continuation audio after the uploaded prefix. It supports optional prompt guidance, loop-friendly ambience mode, multiple variations, and flexible extension length, making it useful for sound design, music continuation, ambient loops, and creative audio workflows.

Why Choose This?

Audio continuation Extend an existing audio clip with newly generated sound that follows the uploaded prefix.
Prompt-guided extension Add an optional text prompt to steer the mood, texture, or direction of the continuation.
Loop-friendly ambience mode Enable ambience to generate audio designed for seamless looping.
Multiple variations Generate up to 4 variations in one request with num_samples.
Flexible extension length Choose how many seconds to append after the prefix with append_duration.
Production-ready API Suitable for sound design, ambient loop creation, music continuation, and background audio workflows.

Parameters

Parameter	Required	Description
audio	Yes	Audio prefix to extend. Prefix duration must be `3–59` seconds, and total output is capped at `60` seconds.
prompt	No	Optional text prompt guiding the extension.
append_duration	No	Number of seconds to add after the prefix. Range: `1–57`. Default: `10`.
ambience	No	When `true`, extend and stitch the result so the tile loops seamlessly. Default: `false`.
double_output	No	Only used when `ambience` is `true`: concatenate the loop with itself for a `2x`-length output. Default: `false`.
num_samples	No	Number of variations to generate. Range: `1–4`. Default: `1`.

How to Use

Upload your audio — provide the source audio clip you want to continue.
Add a prompt (optional) — describe the mood, texture, or direction of the extension.
Set append duration — choose how many seconds of new audio to generate.
Enable ambience (optional) — turn this on if you want a seamless looping result.
Enable double output (optional) — when using ambience, you can concatenate the loop with itself for a longer looped result.
Set number of samples — choose how many variations you want, from 1 to 4.
Submit — run the model and download the generated audio.

Example Prompt

Dark cinematic ambience with distant thunder, soft low-frequency rumble, evolving tension, seamless continuation

Pricing

Pricing is based on generated extension length and number of samples.

Append Duration	1 Sample	2 Samples	3 Samples	4 Samples
1s	$0.01	$0.02	$0.03	$0.04
5s	$0.05	$0.10	$0.15	$0.20
10s	$0.10	$0.20	$0.30	$0.40
20s	$0.20	$0.40	$0.60	$0.80
30s	$0.30	$0.60	$0.90	$1.20
57s	$0.57	$1.14	$1.71	$2.28

Billing Rules

Pricing is $0.01 per generated second
prompt, ambience, and double_output do not affect pricing
Pricing is based on the newly generated extension, not the original uploaded prefix

Best Use Cases

Ambient loop creation — Extend and stitch background ambience for seamless looping.
Music continuation — Add new material after an existing musical phrase or intro.
Sound design — Build evolving effects, textures, and atmospheres from a short prefix.
Game and app audio — Create longer looping backgrounds or environmental sound beds.
Creative prototyping — Generate multiple continuation ideas quickly from a single source clip.

Pro Tips

Use a clean, clearly defined source clip for better continuation quality.
Add a short prompt only when you need stronger directional control.
Use ambience when the result needs to loop smoothly.
Turn on double_output only when you want a longer looped deliverable.
Increase num_samples when you want multiple variations from the same prefix.
Keep the total output length limit in mind when choosing prefix length and append duration.

Notes

audio is required.
Uploaded prefix audio must be between 3 and 59 seconds.
Total output is capped at 60 seconds.
append_duration controls how many new seconds are generated after the prefix.
double_output only applies when ambience is enabled.
Pricing is based on generated extension seconds and sample count.

Related Models

Other Mirelo AI audio generation workflows — Useful when you need fresh generation rather than extension.
Audio loop and ambience workflows — Useful for seamless background and environmental sound generation.

Sfx 1.6 Extend Audio API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/mirelo-ai/sfx-1.6/extend-audio with your input as JSON. The endpoint returns a prediction id; poll the prediction endpoint until status flips to completed, then read the output URL from data.outputs[0]. Examples for Sfx 1.6 Extend Audio below.

HTTP example

# Submit the prediction
curl -X POST "https://api.wavespeed.ai/api/v3/mirelo-ai/sfx-1.6/extend-audio" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY" \
  -d '{
    "audio": "https://example.com/your-audio.mp3",
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "append_duration": 10,
    "ambience": false,
    "double_output": false,
    "num_samples": 1
}'

# Response includes a prediction id. Poll for the result:
curl -X GET "https://api.wavespeed.ai/api/v3/predictions/{request_id}/result" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY"

# When status is "completed", read the output from data.outputs[0].

Node.js example

// npm install wavespeed
const WaveSpeed = require('wavespeed');

const client = new WaveSpeed(); // reads WAVESPEED_API_KEY from env

const result = await client.run("mirelo-ai/sfx-1.6/extend-audio", {
        "audio": "https://example.com/your-audio.mp3",
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "append_duration": 10,
        "ambience": false,
        "double_output": false,
        "num_samples": 1
});

console.log(result.outputs[0]); // → URL of the generated output

Python example

# pip install wavespeed
import wavespeed

output = wavespeed.run(
    "mirelo-ai/sfx-1.6/extend-audio",
    {
    "audio": "https://example.com/your-audio.mp3",
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "append_duration": 10,
    "ambience": false,
    "double_output": false,
    "num_samples": 1
}
)

print(output["outputs"][0])  # → URL of the generated output

Sfx 1.6 Extend Audio API — Frequently asked questions

What is the Sfx 1.6 Extend Audio API?

Sfx 1.6 Extend Audio is a Mirelo Ai model for AI inference, exposed as a REST API on WaveSpeedAI. 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. You can call it programmatically or try it from the playground above.

How do I call the Sfx 1.6 Extend Audio API?

POST your input parameters to the model's REST endpoint (shown in the API tab of this playground) with your WaveSpeedAI API key in the Authorization header. Submission returns a prediction ID; poll the prediction endpoint until status flips to "completed", then read the output URL from the result. The playground generates a ready-to-paste code sample in Python, JavaScript, or cURL for whatever inputs you've set. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/mirelo-ai/mirelo-ai-sfx-1.6-extend-audio.

How much does Sfx 1.6 Extend Audio cost per run?

Sfx 1.6 Extend Audio starts at $0.010 per run. That figure is the base price — the final charge scales with the parameters you set in the form (output size, length, count, references, or whatever knobs this model exposes), so a higher-quality or larger output costs more than a minimal one. The exact cost for your current input is shown live next to the Generate button before you submit, and the actual per-call charge is recorded on the prediction afterwards.

What inputs does Sfx 1.6 Extend Audio accept?

Key inputs: `prompt`, `audio`, `ambience`, `append_duration`, `double_output`, `num_samples`. The full JSON schema (types, defaults, allowed values) is rendered above the Generate button and mirrored in the API reference at https://wavespeed.ai/docs/docs-api/mirelo-ai/mirelo-ai-sfx-1.6-extend-audio.

How do I get started with the Sfx 1.6 Extend Audio API?

Sign up for a free WaveSpeedAI account to claim starter credits, copy your API key from /accesskey, then call the endpoint shown in the API tab of the playground. The playground also auto-generates a code sample in Python, JavaScript, or cURL for the parameters you've set.

Can I use Sfx 1.6 Extend Audio outputs commercially?

Commercial usage rights depend on the model's license, set by its provider (Mirelo Ai). The license summary appears on the model card above; see WaveSpeedAI's Terms of Service for platform-level conditions.

ExamplesView all

Related Models

README

Mirelo AI SFX 1.6 Extend Audio

Why Choose This?

Parameters

How to Use

Example Prompt

Pricing

Billing Rules

Best Use Cases

Pro Tips

Notes

Related Models

Sfx 1.6 Extend Audio API — Quick start

Sfx 1.6 Extend Audio API — Frequently asked questions