API reference · ace

ace/ace-step/audio-outpaint

Integrate this model through SandBase's unified API, with production-ready schemas and examples.

AUDIOAsyncOpen model

Production endpoint

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OpenAI-compatible endpoint with unified authentication and usage tracking.

POSThttps://api.sandbase.ai/v1/run

Model IDace/ace-step/audio-outpaint

Input Schema

15 parameters · 0 required · 15 optional

Parameter	Type	Required	Description
`seed`	integer	Optional	Random seed for reproducibility. If not provided, a random seed will be used.
`tags`	string	Optional	Comma-separated list of genre tags to control the style of the generated audio.
`audio`	string	Optional	URL of the audio file to be outpainted.
`lyrics`	string	Optional	Lyrics to be sung in the audio. If not provided or if [inst] or [instrumental] is the content of this field, no lyrics will be sung. Use control structures like [verse], [chorus] and [bridge] to control the structure of the song. · Default: ""
`guidance_type`	string	Optional	Type of CFG to use for the generation process. · Options: cfg, apg, cfg_star · Default: "apg" cfgapgcfg_star
`guidance_scale`	number	Optional	Min: 0 · Max: 200 · Default: 15
`number_of_steps`	integer	Optional	Number of steps to generate the audio. · Min: 3 · Max: 60 · Default: 27
`granularity_scale`	integer	Optional	Granularity scale for the generation process. Higher values can reduce artifacts. · Min: -100 · Max: 100 · Default: 10
`guidance_interval`	number	Optional	Guidance interval for the generation. 0.5 means only apply guidance in the middle steps (0.25 * infer_steps to 0.75 * infer_steps) · Min: 0 · Max: 1 · Default: 0.5
`tag_guidance_scale`	number	Optional	Tag guidance scale for the generation. · Min: 0 · Max: 10 · Default: 5
`lyric_guidance_scale`	number	Optional	Lyric guidance scale for the generation. · Min: 0 · Max: 10 · Default: 1.5
`extend_after_duration`	number	Optional	Duration in seconds to extend the audio from the end. · Min: 0 · Max: 240 · Default: 30
`extend_before_duration`	number	Optional	Duration in seconds to extend the audio from the start. · Min: 0 · Max: 240 · Default: 0
`minimum_guidance_scale`	number	Optional	Minimum guidance scale for the generation after the decay. · Min: 0 · Max: 200 · Default: 3
`guidance_interval_decay`	number	Optional	Guidance interval decay for the generation. Guidance scale will decay from guidance_scale to min_guidance_scale in the interval. 0.0 means no decay. · Min: 0 · Max: 1 · Default: 0

Output Schema

Field	Type	Description
`id`	string	Unique identifier for the generation task
`status`	string	Task status: pending, running, completed, failed, timeout
`model`	string	Model used for the generation
`outputs`	array	Array of output items
`outputs[].url`	string	URL of the generated artifact
`outputs[].content_type`	string	MIME type (e.g. image/png, video/mp4)
`error`	object \| null	Error details if failed, null on success
`error.type`	string	Machine-readable error type code
`error.message`	string	Human-readable error description

Async Workflow

This model uses asynchronous execution. Submit a request and poll for the result.

Submit — POST to /v1/run, receive an id
Poll — GET /v1/run/{id} until status is completed, failed, or timeout
Retrieve — Read outputs from the completed response

Code Examples

Ready-to-run snippets

# Step 1: Submit
curl -X POST https://api.sandbase.ai/v1/run \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
  "model": "ace/ace-step/audio-outpaint",
  "tags": "lofi, hiphop, drum and bass, trap, chill",
  "audio": "https://storage.googleapis.com/falserverless/example_inputs/ace-step-audio-to-audio.wav",
  "lyrics": "",
  "guidance_type": "apg",
  "guidance_scale": 15,
  "number_of_steps": 27,
  "granularity_scale": 10,
  "guidance_interval": 0.5,
  "tag_guidance_scale": 5,
  "lyric_guidance_scale": 1.5,
  "extend_after_duration": 30,
  "extend_before_duration": 0,
  "minimum_guidance_scale": 3,
  "guidance_interval_decay": 0,
  "prompt": "a beautiful sunset over mountains"
}'

# Step 2: Poll result (replace <id>)
curl https://api.sandbase.ai/v1/run/<id> \
  -H "Authorization: Bearer YOUR_API_KEY"

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