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2026/9/17 19:47 (UTC+8) · Docs Update · ByteDance 📚 Seedance 2.5 returns a 400 when you set an aspect ratio and duration? The task was most likely classified as video editing A real ticket: the request carried one reference_video, the prompt asked to “upscale the video and keep all elements unchanged”, and it also set ratio: "4:3" and duration: 15. Submission failed at once with a 400 TaskTypeConstraint. With a reference video, 2.5 reads the prompt’s intent to classify the task as reference-to-video, video editing, or video extension. Editing locks the aspect ratio and duration to the source video, so ratio must be adaptive and duration must be -1. omni_reference_task_type accepts only auto / edit / extend; no value locks a task to reference-to-video. The new FAQ covers the classification rules, prompt rewrites, and three reliable approaches (the general adaptive + -1 setup, rewriting the prompt to keep a fixed ratio and duration, and a retry in code). See Seedance 2.5: Reference-to-Video vs. Video Editing. The docs sidebar under “Seedance 2.0 / 2.5” now has an “SD FAQ” subsection that collects the Seedance FAQs.
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