Ace Step

# ACE Step — Pro Pack on RunComfy

Tag-driven music generation, inpainting, and outpainting with StepFun-AI's **ACE Step** open-weights model. Four CLI-reachable endpoints, $0.0002–0.0003 per second of audio, up to 4 minutes per call.

[runcomfy.com](https://www.runcomfy.com/?utm_source=skills.sh&utm_medium=skill&utm_campaign=ace-step) · [ACE Step base](https://www.runcomfy.com/models/acestep-ai/ace-step/text-to-audio?utm_source=skills.sh&utm_medium=skill&utm_campaign=ace-step) · [ACE Step 1.5](https://www.runcomfy.com/models/acestep-ai/ace-step-1.5/text-to-audio?utm_source=skills.sh&utm_medium=skill&utm_campaign=ace-step) · [CLI docs](https://docs.runcomfy.com/cli/introduction?utm_source=skills.sh&utm_medium=skill&utm_campaign=ace-step)

## Install this skill

```bash npx skills add agentspace-so/runcomfy-agent-skills --skill ace-step -g ```

## Powered by the RunComfy CLI

**Step 1 — install** (one of, see the `runcomfy-cli` skill for details):

```bash npm i -g @runcomfy/cli # global install npx -y @runcomfy/cli --version # zero-install ```

**Step 2 — sign in** (or set `RUNCOMFY_TOKEN` env var in CI / containers):

```bash runcomfy login ```

**Step 3 — generate**:

```bash runcomfy run acestep-ai/ace-step/text-to-audio \ --input '{"tags": "..."}' \ --output-dir ./out ```

CLI deep dive: [`runcomfy-cli`](https://www.skills.sh/agentspace-so/runcomfy-agent-skills/runcomfy-cli) skill.

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## Pick the right endpoint

Listed newest first.

**ACE Step 1.5 (text-to-audio)** — `acestep-ai/ace-step-1.5/text-to-audio` > Latest ACE Step generation. **50+ language vocal support**, refined structured-lyric handling, otherwise same shape as base. Slightly higher cost ($0.0003/s vs $0.0002/s). > Pick for: multilingual lyrics, hero-quality vocal tracks, vocal songs that need clean section structure. > Avoid for: cost-sensitive batches where the base model is good enough.

**ACE Step (text-to-audio)** — `acestep-ai/ace-step/text-to-audio` *(default — cheap & fast)* > Original ACE Step. Tag-driven composition, optional lyrics, 5–240 s stereo. $0.0002/s — ~27× cheaper than ElevenLabs Music. > Pick for: high-volume drafts, background music, jingles, game loops, cost-sensitive iteration. > Avoid for: maximally polished commercial vocal hooks — try **ACE Step 1.5** or **ElevenLabs Music** for those.

**ACE Step (audio-inpaint)** — `acestep-ai/ace-step/audio-inpaint` > Regenerate a **time range** inside an existing track (not mask-based; uses `start_time` / `end_time` in seconds, each anchored to track start or end). > Pick for: fix a bad chorus in the middle, swap the bridge, replace a 20 s section without re-rendering the whole song. > Avoid for: edits that aren't time-bounded — those don't fit the schema.

**ACE Step (audio-outpaint)** — `acestep-ai/ace-step/audio-outpaint` > Extend an existing track **bidirectionally** — add intro before, outro after, or both. > Pick for: lengthening a 30 s draft into a 2 min cut, adding a fade-in, building a longer arrangement around an existing hook. > Avoid for: extending a track past 4 min total — chain calls instead.

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## Route 1: ACE Step text-to-audio (default)

**Model**: `acestep-ai/ace-step/text-to-audio` (or `acestep-ai/ace-step-1.5/text-to-audio` for the 1.5 variant)

### Schema (both variants — same shape)

| Field | Type | Required | Default | Notes | |---|---|---|---|---| | `tags` | string | yes | — | **Comma-separated** genre / mood / instrument tags. Drives composition | | `lyrics` | string | no | — | Vocal content. Use section markers `[Verse]`, `[Chorus]`, `[Bridge]`. Use `[inst]` or `[instrumental]` for no vocals | | `duration` | int | no | `60` | Audio length in seconds. **5–240** (max 4 min per call) | | `seed` | int | no | `-1` | Reproducibility; `-1` randomizes |

**Pricing**: ACE Step $0.0002/s · ACE Step 1.5 $0.0003/s. 60 s ≈ $0.012 / $0.018; 240 s ≈ $0.048 / $0.072.

### Invoke

**Tag-driven instrumental:**

```bash runcomfy run acestep-ai/ace-step/text-to-audio \ --input '{ "tags": "lo-fi hip-hop, mellow, vinyl crackle, rhodes piano, soft drums, 75 BPM", "lyrics": "[inst]", "duration": 90 }' \ --output-dir ./out ```

**Full vocal song with structure (use 1.5 for multilingual):**

```bash runcomfy run acestep-ai/ace-step-1.5/text-to-audio \ --input '{ "tags": "indie pop, anthemic, electric guitar, driving drums, female vocal, 120 BPM", "lyrics": "[Verse]\nChalk on the palms, laces double-knotted\nMorning on the ridge, the sun is rising\n[Chorus]\nWe rise, we strike, we never fade out\nWe rise, we strike, we sing it loud\n[Bridge]\nSoft piano breakdown\n[Outro]\nFull band, fade", "duration": 60 }' \ --output-dir ./out ```

### Prompting tips

- **Tags do the heavy lifting** — be specific: `"lo-fi hip-hop, mellow, vinyl crackle, rhodes piano, soft drums, 75 BPM"` beats `"chill music"`. - **Include BPM** in tags when it matters — ACE respects tempo language. - **Lyrics with section markers**: `[Verse]`, `[Choru