Halloween video sound design: a Lyria prompt that stays scary

How do you make Halloween video sound design with AI? Write a brief with a number for tempo, a key, two to four textured instruments and one named moment, close with "Instrumental, no vocals.", and send it to the Sume Music Router. The Music 1.0 docs list those axes for a scene-specific brief and warn that they are creative directions, not guaranteed settings, so you listen to what comes back.

Horror music works on restraint. A bed that holds one low note and a single sharp event beats a wall of noise under dialogue, and a prompt is a good place to say so.

Build the brief from the seven axes

The docs' table of axes is a checklist. For a haunted-house reveal, fill each one with a decision.

Send it

Keep exclusions in the positive prompt, because a non-empty negative_prompt returns HTTP 400. If the model reports lyrics or a section map, they arrive in result.lyrics.

import os
import requests

r = requests.post(
    "https://api.sume.com/v1/music-router/generate",
    headers={
        "Authorization": "Bearer " + os.environ["SUME_API_KEY"],
        "Idempotency-Key": "halloween-cue-001",
    },
    json={
        "model": "sume/music-auto",
        "prompt": "Hushed dread, dark ambient horror score, 60 BPM, C phrygian. Bowed cello drone, detuned music box, sub swell. The music box stops dead at 0:20 and a low hit lands at 0:22. Dry and close, 1978 production. A 30-second track. Instrumental, no vocals.",
        "mode": "sync",
        "wait_timeout_seconds": 30,
    },
    timeout=60,
)
print(r.status_code)
print(r.json())

Under dialogue and over a silent clip

For a clip with a voice, set soundtrack.duck_db on the Timeline 1.0 render so the bed gets quieter under speech. For a silent clip, the captions endpoint fails with caption_no_speech; send cues with text, start and end to burn authored overlay lines such as a title card, no speech-to-text involved.

• Bed: soundtrack.url with gain_db and fade_out_seconds.
• Ducking: duck_db from 0 to 20, only with a real audio spine.
• Silent title cards: cues on /v1/video-captions.

Do not do

Do not name a film composer or a franchise in the prompt and expect a copy; the docs describe no such behavior, and a brief is stronger when it names instruments and structure.