edge_fades_exceed_output: fade in and out too long for the video

Timeline 1.0 returns edge_fades_exceed_output when output.fade_in_seconds plus output.fade_out_seconds is longer than the output. Each value is limited to 0 to 5 seconds, and the sum has to stay within audio.duration_seconds. Shorten one of them, or lengthen the render.

The limits come from the Timeline docs, read 2026-10-01.

What are the fade limits?

Why does a 6-second fade fail on a long video?

The 5-second cap is per edge, independent of how long the video is. A fade of 6 seconds is outside 0 to 5 even on a ten-minute render. A short render hits the other rule: on an 8-second output, a 5-second fade in and a 4-second fade out sum to 9, which is more than 8.

What about the music fade?

The optional soundtrack bed has its own fade_out_seconds, capped at 10. The docs list soundtrack_fade_exceeds_output for a fade longer than the spine, so a 10-second music fade on a 6-second render fails even though 10 is allowed in general. For ducking music under a voice, see Timeline duck.

How do I avoid the error before rendering?

Clamp in your own code before you submit: keep each edge fade at or below 5, and keep the sum at or below audio.duration_seconds. The unbilled plan call also runs the validation without creating a job or reserving credits.

One related note from the Descript changelog (September 17): smart transitions no longer fade in on the first scene, so a video does not open on black. In Timeline the first slot cannot carry a transition at all (transition_on_first_segment); an opening fade is set with output.fade_in_seconds.