Timeline invalid_segment_timing and segment_overlap: fix your starts
Sume timeline returns invalid_segment_timing or segment_overlap when video starts do not increase or slots overlap past the transition. Fix the start values.
invalid_segment_timing and segment_overlap from Sume Timeline 1.0 mean that your video[].start values do not increase, or two slots overlap by more than their crossfade. Fix the starts so each one is later than the one before, and keep video[0].start at exactly 0. Run the unbilled /plan call first to see the problem without a charge. Source: Timeline 1.0, read 2026-10-06.
What are the timing rules?
Declared starts are authoritative, and the compiler compensates for a crossfade without pre-shifting your numbers.
| Rule | Value | Code when broken |
|---|---|---|
| First slot start | video[0].start is 0 | timeline_must_start_at_zero |
| Later starts | Must increase | invalid_segment_timing |
| Overlap | Not past the xfade | segment_overlap |
| Transition on first slot | Not allowed | transition_on_first_segment |
| Slot length | At least 0.2 s | See the program table |
How do I fix it?
Compute each start as the previous start plus the previous on-screen duration. A transition is at most 1 second and at most 50% of the shorter neighbour, so keep slots long enough for the fade you ask for. Coverage may stop at most 0.5 seconds before the end of the spine.
- Use
POST /v1/timeline-1.0/planbefore the paid render; it is unbilled. - Slots go up to 200 per timeline; more than 12 chunk automatically on
render.strategy: auto. - Price is $0.10 per ceil output minute.
Sources
Related posts
More in Media tools
- Timeline output.fps: omit it, or you may resample and get judder
Timeline takes output.fps of 24, 25, 30 or 60 and warns when it differs from the sources. YouTube Shorts and TikTok ad pages list no frame rate.
- Render a 1-minute video with the Timeline API: $0.10
Sume Timeline 1.0 renders at $0.10 per ceil(output minute), so 1 minute of finished video is $0.10. Compose and audio steps are $0.02 and $0.01 per job.
- Render a 10-minute video with the Timeline API: $1.00
Sume Timeline 1.0 renders at $0.10 per ceil(output minute), so 10 minutes of finished video is $1.00. Compose and audio steps are $0.02 and $0.01 per job.
- Render a 2-minute video with the Timeline API: $0.20
Sume Timeline 1.0 renders at $0.10 per ceil(output minute), so 2 minutes of finished video is $0.20. Compose and audio steps are $0.02 and $0.01 per job.
Written by Sume