Timeline render fails bgm_source_not_found: fix a dead soundtrack URL

bgm_source_not_found is the public_reason Timeline 1.0 returns when the soundtrack URL answers 404 or 410. It is not a missing clip. Re-import the track or drop the soundtrack block, then submit the render again.

How to tell it from source_not_found

The error details carry a source_slot. A dead video clip reports video[N], a dead voiceover reports audio or audio.parts[N], and a dead music bed reports soundtrack. The API uses the separate code for the soundtrack slot so you do not go hunting through your clips. The suggested next_action is omit_soundtrack_or_pick_catalog_track.

Fix steps

Open the soundtrack URL from outside your pipeline and confirm it returns audio. If the file expired or was deleted, regenerate it, for instance with the Music Router, and pass the new artifact URL. If the bed is optional, remove soundtrack and render without it.

• Check the URL is on media.sume.com and not a deleted artifact.
• Regenerate the music if the artifact is gone.
• Keep duck_db only when a real voiceover spine is present, because ducking needs speech.

Prevent it

Store artifact URLs with the job that produced them and rebuild a render request from stored values instead of pasted links. A 404 is not retryable on its own; the same body fails again until the URL is replaced. The timeline audio post covers building the voiceover spine.