Christmas ad music: an instrumental Lyria brief that sells

What music suits a Christmas ad? An instrumental bed with a clear tempo, a recognisable seasonal color from instruments rather than a famous melody, and room for a voiceover. With Sume you describe that in one prompt to the Music Router, add "Instrumental, no vocals.", and let Timeline 1.0 handle the level and the ending.

The docs set the ground rules: the prompt is 1 to 5000 characters, length is steered in the prompt, duration is rejected, and a non-empty negative_prompt returns a 400, so every exclusion goes into the positive wording.

Write the brief for a voiceover

A bed under speech needs space in the middle of the sound. Ask for it by naming what plays and what stays out of the way. The seven-axis structure in the Music 1.0 docs gives you slots for each decision.

Send the prompt

A synchronous request waits up to 30 seconds for a finished job; otherwise poll the job envelope.

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": "christmas-ad-001",
    },
    json={
        "model": "sume/music-auto",
        "prompt": "Warm and hopeful chamber pop with a jazz lean, 96 BPM, G major with a lydian lift. Celesta, upright bass, brushed drums, sleigh bells low in the mix. Sparse intro, the celesta melody enters at 0:06, full return at 0:22. A 30-second track. Instrumental, no vocals.",
        "mode": "sync",
        "wait_timeout_seconds": 30,
    },
    timeout=60,
)
print(r.status_code)
print(r.json())

Lay it under the voice

On the render request, the audio spine carries the voiceover and soundtrack carries the bed. duck_db lowers the bed under speech and takes values from 0 to 20, fade_out_seconds ends it softly (up to 10), and output.fade_in_seconds and fade_out_seconds handle the picture edges up to 5 seconds each. If a fade is longer than the audio, the render refuses it with soundtrack_fade_exceeds_output.

Check before you ship

Listen to the result and compare it to the brief. The docs state the axes are directions, not guaranteed settings, so plan a second pass. If the bed is almost right, change one axis, not all seven.