Music bed for a SaaS product demo: a Lyria brief and ducking

For a product-demo video, ask the Music Router for a steady, sparse instrumental in a fixed tempo, then place it as a Timeline soundtrack with duck_db so it dips under the narration. Write the brief on seven axes, end it with "Instrumental, no vocals.", and state the length in words. One generation costs a fixed $0.125, and a one-minute render adds $0.10.

The brief

The Music 1.0 page recommends a scene-specific brief with seven axes. For a demo, choose calm over clever: a clear tempo, few instruments, and an arc that stays out of the narration's way. Example prompt: "Focused, quietly optimistic tech-pop, 96 BPM, A minor. Soft Rhodes pulse, muted sub bass, light shaker, one glassy pad. Sparse for the first minute with a slight lift at 0:40, nothing in the vocal range. 2020s production, dry and close. A 90-second track. Instrumental, no vocals."

• Emotion: named precisely (focused, quietly optimistic).
• Tempo as a number and key: so it is repeatable.
• Two to four instruments with texture.
• One named moment, not a dramatic build.
• Length written into the prompt, because duration is rejected.

The render

Put the narration as the audio spine and the music as soundtrack. Timeline 1.0 accepts soundtrack with url, gain_db, loop, fade_out_seconds up to 10 and duck_db from 0 to 20. duck_db needs a real spine, so it works under a voiceover and is refused when the spine is silence (duck_requires_audio_spine). Start with duck_db around 10 and adjust by ear.

Check before you publish

Call the unbilled POST /v1/timeline-1.0/plan first; it returns billable_minutes and estimated_cost_usd_micros without creating a job. Then listen to the render at the quietest speaker you expect viewers to use, and confirm the narration is clear. The plan call cannot predict warnings about padded or looped sources, which appear on the finished job.

If the track is shorter than the video, set loop or ask for a longer one in the prompt. For results and polling, see Jobs and results.