Mirelo Ai Sfx 1.6 Extend Audio
Playground
Try it 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.
Features
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
ambienceto generate audio designed for seamless looping. -
Multiple variations Generate up to
4variations in one request withnum_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
1to4. - 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, anddouble_outputdo 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
ambiencewhen the result needs to loop smoothly. - Turn on
double_outputonly when you want a longer looped deliverable. - Increase
num_sampleswhen you want multiple variations from the same prefix. - Keep the total output length limit in mind when choosing prefix length and append duration.
Notes
audiois required.- Uploaded prefix audio must be between
3and59seconds. - Total output is capped at
60seconds. append_durationcontrols how many new seconds are generated after the prefix.double_outputonly applies whenambienceis 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.
Authentication
For authentication details, please refer to the Authentication Guide.
API Endpoints
Submit Task & Query Result
# Submit the task
curl --location --request POST "https://api.wavespeed.ai/api/v3/mirelo-ai/sfx-1.6/extend-audio" \
--header "Content-Type: application/json" \
--header "Authorization: Bearer ${WAVESPEED_API_KEY}" \
--data-raw '{
"append_duration": 10,
"ambience": false,
"double_output": false,
"num_samples": 1
}'
# Get the result
curl --location --request GET "https://api.wavespeed.ai/api/v3/predictions/${requestId}/result" \
--header "Authorization: Bearer ${WAVESPEED_API_KEY}"
Parameters
Task Submission Parameters
Request Parameters
| Parameter | Type | Required | Default | Range | Description |
|---|---|---|---|---|---|
| audio | string | Yes | - | - | Audio prefix to extend. Prefix duration must be 3 to 59 seconds, and total output is capped at 60 seconds. |
| prompt | string | No | - | Optional text prompt guiding the extension. | |
| append_duration | number | No | 10 | 1 ~ 57 | Seconds to add after the prefix. Total output is capped at 60 seconds. |
| ambience | boolean | No | false | - | When true, extend and stitch the result so the tile loops seamlessly. |
| double_output | boolean | No | false | - | Only used when ambience is true: concatenate the loop with itself for a 2x-length output. |
| num_samples | integer | No | 1 | 1 ~ 4 | Number of variations to generate. |
Response Parameters
| Parameter | Type | Description |
|---|---|---|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., “success”) |
| data.id | string | Unique identifier for the prediction, Task Id |
| data.model | string | Model ID used for the prediction |
| data.outputs | array | Array of URLs to the generated content (empty when status is not completed) |
| data.urls | object | Object containing related API endpoints |
| data.urls.get | string | URL to retrieve the prediction result |
| data.status | string | Status of the task: created, processing, completed, or failed |
| data.created_at | string | ISO timestamp of when the request was created (e.g., “2023-04-01T12:34:56.789Z”) |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |
Result Request Parameters
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| id | string | Yes | - | Task ID |
Result Response Parameters
| Parameter | Type | Description |
|---|---|---|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., “success”) |
| data | object | The prediction data object containing all details |
| data.id | string | Unique identifier for the prediction, the ID of the prediction to get |
| data.model | string | Model ID used for the prediction |
| data.outputs | string | Array of URLs to the generated content. |
| data.urls | object | Object containing related API endpoints |
| data.urls.get | string | URL to retrieve the prediction result |
| data.status | string | Status of the task: created, processing, completed, or failed |
| data.created_at | string | ISO timestamp of when the request was created (e.g., “2023-04-01T12:34:56.789Z”) |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |