Mirelo SFX1.6 Extend Audio 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

1. Upload your audio — provide the source audio clip you want to continue.
2. Add a prompt (optional) — describe the mood, texture, or direction of the extension.
3. Set append duration — choose how many seconds of new audio to generate.
4. Enable ambience (optional) — turn this on if you want a seamless looping result.
5. Enable double output (optional) — when using ambience, you can concatenate the loop with itself for a longer looped result.
6. Set number of samples — choose how many variations you want, from 1 to 4.
7. 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.