AI music generation with ACE-Step 1.5 — background music, vocal tracks, covers, stem extraction, audio repainting, and continuation for video production. Use when generating music, soundtracks, jingles, or working with audio stems. Triggers include background music, soundtrack, jingle, music generat

ACE Step 1.5 Music Generation Open source music generation via tools/music gen.py . Cloud providers: acemusic (default) — Official ACE Step cloud API with XL Turbo (4B) model + 5Hz LM thinking mode. Free API key from [acemusic.ai/api key](https://acemusic.ai/api key). No GPU required. modal — Self hosted ACE Step 2B Turbo on Modal. Requires MODAL MUSIC GEN ENDPOINT URL . runpod — Self hosted ACE Step 2B Turbo on RunPod. Requires RUNPOD ACESTEP ENDPOINT ID . Setup Quick Reference Fixing "Samey" Output If generated music sounds repetitive or lacks variety, try these in order: 1. Use acemusic cloud (default) — the XL Turbo 4B model is significantly more capable than the 2B model on Modal/RunPod 2. Keep thinking mode on (default for acemusic) — the 5Hz LM enriches sparse prompts into detailed musical descriptions 3. Generate variations — variations 4 generates 4 takes, pick the best 4. Use stochastic inference — infer method sde adds randomness (same seed gives different results) 5. Vary BPM and key across scenes — don't use the same preset for every scene 6. Write sparser prompts — "Upbeat indie rock" gives the model more creative freedom than a hyper detailed description 7. Vary seeds — omit seed to let each generation be unique Creating a Song (Step by Step) 1. Instrumental background track (simplest) 2. Song with vocals and lyrics Write lyrics in a temp file or pass inline. Use structure tags to control song sections. 3. Repaint a weak section If the chorus sounds weak, regenerate just that section: 4. Continue/extend a track Key tips for good results Caption = overall style (genre, instruments, mood, production quality) Lyrics = temporal structure (verse/chorus flow, vocal delivery) UPPERCASE in lyrics = high vocal intensity Parentheses = background vocals: "We rise (together)" Keep 6 10 syllables per line for natural rhythm Don't describe the melody in the caption — describe the sound and feeling Use seed to lock randomness when iterating on prompt/lyrics Controlling vocal gender The model doesn't reliably follow "female vocal" or "male vocal" on its own. Use both of these together: 1. In the prompt : Be explicit — "solo female singer, alto voice" or "female vocalist only, breathy intimate voice". Adding an artist reference helps (e.g., "Brandi Carlile style"). 2. In the lyrics : Add [female vocal] tags before each section: Just saying "female vocal" in the prompt alone is often ignored. The combination of prompt + lyrics tags is what works. Duets and vocal trading For duets with male/female vocals trading verses, use both the prompt and per section lyrics tags: Prompt : "duet, male and female vocals trading verses, warm harmonies on chorus" Lyrics : Tag each section with who sings it: This reliably produces vocal trading between sections and harmonies on shared parts. Scene Presets Preset BPM Key Use Case corporate bg 110 C Major Professional background, presentations upbeat tech 128 G Major Product launches, tech demos ambient 72 D Major Overview slides, reflective content dramatic 90 D Minor Reveals, announcements tension 85 A Minor Problem statements, challenges hopeful 120 C Major Solution reveals, resolutions cta 135 E Major Call to action, closing energy lofi 85 F Major Screen recordings, coding demos Task Types text2music (default) Generate music from text prompt + optional lyrics. cover Style transfer from reference audio. Control blend with cover strength (0.0 1.0): 0.2 — Loose style inspiration (more creative freedom) 0.5 — Balanced style transfer 0.7 — Close to original structure (default) 1.0 — Maximum fidelity to source extract Stem separation — isolate individual tracks from mixed audio. Tracks: vocals , drums , bass , guitar , piano , keyboard , strings , brass , woodwinds , other repainting (acemusic only) Regenerate a specific time segment within existing audio while preserving the rest. continuation (acemusic only) Extend existing audio by continuing from where it ends. Prompt Engineering Caption Writing — Layer Dimensions Write captions by layering multiple descriptive dimensions rather than single word descriptions. Dimensions to include: Genre/Style : pop, rock, jazz, electronic, lo fi, synthwave, orchestral Emotion/Mood : melancholic, euphoric, dreamy, nostalgic, intimate, tense Instruments : acoustic guitar, synth pads, 808 drums, strings, brass, piano Timbre : warm, crisp, airy, punchy, lush, polished, raw Era : "80s synth pop", "modern indie", "classical romantic" Production : lo fi, studio polished, live recording, cinematic Vocal : breathy, powerful, falsetto, raspy, spoken word (or "instrumental") Good : "Slow melancholic piano ballad with intimate female vocal, warm strings building to powerful chorus, studio polished production" Bad : "Sad song" Key Principles 1. Specificity over vagueness — describe instruments, mood, production style 2. Avoid contradictions — don't request "classical strings" and "hardcore metal" simultaneously 3. Repetition reinforces priority — repeat important elements for emphasis 4. Sparse captions = more creative freedom — detailed captions constrain the model 5. Use metadata params for BPM/key — don't write "120 BPM" in the caption, use bpm 120 Lyrics Formatting Structure tags (use in lyrics, not caption): Vocal control (prefix lines or sections): Energy indicators: UPPERCASE = high intensity ("WE RISE ABOVE") Parentheses = background vocals ("We rise (together)") Keep 6 10 syllables per line within sections for natural rhythm Video Production Integration Music for Scene Types Scene Preset Duration Notes Title dramatic or ambient 3 5s Short, mood setting Problem tension 10 15s Dark, unsettling Solution hopeful 10 15s Relief, optimism Demo lofi or corporate bg 30 120s Non distracting, matches demo length Stats upbeat tech 8 12s Building credibility CTA cta 5 10s Maximum energy, punchy Credits ambient 5 10s Gentle fade out Timing Workflow 1. Plan scene durations first (from voiceover script) 2. Generate music to match: duration <scene seconds 3. Music duration is precise (within 0.1s of requested) 4. For background music spanning multiple scenes: generate one long track Combining with Voiceover Background music should be mixed at 10 20% volume in Remotion: For music under narration: use instrumental presets ( corporate bg , ambient , lofi ). For music forward scenes (title, CTA): can use higher volume or vocal tracks. Brand Consistency Use brand <name to load hints from brands/<name /brand.json . Use cover reference brand theme.mp3 to create variations of a brand's sonic identity. For consistent sound across a project: fix the seed ( seed 42 ) and vary only duration/prompt. Advanced Parameters Flag Default Description thinking on (acemusic) 5Hz LM enriches prompts and generates audio codes no thinking Faster generation, skip LM reasoning variations N 1 Generate N variations (1 8, acemusic only) guidance scale 7.0 Prompt adherence (1.0 15.0) infer method ode ode (deterministic) or sde (stochastic, more variety) seed random Lock randomness for reproducibility Technical Details acemusic cloud : XL Turbo 4B DiT + 4B LM, best quality, ~5 15s per generation Modal/RunPod : Standard Turbo 2B DiT, no LM, ~2 3s per generation Output : 48kHz MP3/WAV/FLAC Duration range : 10 600 seconds BPM range : 30 300 When NOT to use ACE Step Voice cloning — use Qwen3 TTS or ElevenLabs instead Sound effects — use ElevenLabs SFX ( tools/sfx.py ) Speech/narration — use voiceover tools, not music gen Stem extraction from video — extract audio first with FFmpeg, then use extract

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