Loopable BGM for a 90-second video: loopable flag plus soundtrack loop

Each track in Sume's BGM catalog has a loopable field. For a video longer than the track, choose a loopable track, set loop: true on the Timeline soundtrack, and add fade_out_seconds (up to 10) so it ends cleanly. A non-loopable track repeated end to end may show a seam where the ending meets the opening.

What the catalog tells you

The catalog is version bgm_catalog_v3. It has 48 first-party loops hosted on media.sume.com plus licensed Kevin MacLeod beds. Every track carries bpm, energy, loopable, moods, genres, tags, video_genres, product_categories and locales. The loopable flag says whether the track was built to repeat.

Use bgm_list or bgm_pick to find tracks, and filter on the fields that matter for a long video: loopable first, then energy.

The soundtrack object

In a Timeline 1.0 render, soundtrack takes url, gain_db, loop, fade_out_seconds and duck_db. fade_out_seconds is capped at 10. duck_db is 0 to 20 and needs a real audio spine, so a voiceover must be present for ducking to do anything.

Replace the slug with a real track from the catalog. The gain and duck values are examples; set them by ear against your voiceover.

{
  "soundtrack": {
    "url": "https://media.sume.com/assets/bgm/your-track-slug.mp3",
    "gain_db": -18,
    "loop": true,
    "fade_out_seconds": 6,
    "duck_db": 10
  }
}

Attribution for licensed beds

The Kevin MacLeod km-* tracks are CC BY 4.0 and need attribution. First-party Sume loops do not. The catalog carries an attribution field on those tracks; the attribution post shows where to read it.

If you do not want to credit anyone in the caption or description, filter to first-party tracks.

When the bed is too short and not loopable

If no loopable track matches your mood, generate one with Music Router at $0.125 and write the length in the prompt, or use a longer first-party loop. Looping a non-loopable track is possible, but listen at the join. The fade out is for the ending, not for hiding a seam in the middle.

Check bgm_pick's tier too. A catalog_fallback or widened result may have returned a track that is loopable but off-mood; see the match tiers explained.

Test the seam

Render a short cut that covers one loop boundary and listen to it. A loopable track should pass the join without a click or a rhythm break. If it does not, try another track, or lower gain_db so the seam is less noticeable under the voice.

This takes a minute and saves a re-render of the full video.