How to Use Seedance 2.5: A Quick Start Guide

You can go from idea to finished clip in four steps: set up your APIMart account, pick the right Seedance 2.5 mode, set length and resolution, then review and save the result. You can run Seedance 2.5 on APIMart without writing any code first, and move to code later when the workflow is settled.

Here is the short version:

• Pick a mode: text to video, reference-based video, first frame or first and last frames, video edit, or video extend.
• Set the output: clips run 4 to 30 seconds, at 480p, 720p or 1080p, with synced audio on by default.
• Draft first: make a 480p draft, check motion and framing, then produce the 1080p final from the same setup.
• Watch the common traps: 2K and 4K are not supported, first-frame, edit and extend tasks need the adaptive aspect ratio, and real-person faces must be approved in the asset library first.

Seedance 2.5 is ByteDance's newest Seedance video model. Compared with Seedance 2.0, it supports longer clips and far more reference material, while Seedance 2.0 Fast and Mini remain the lighter options for quick drafts.

Key Takeaways

• Seedance 2.5 supports five modes: text to video, reference-based video, first frame or first and last frames, video edit and video extend.
• Clips run 4 to 30 seconds at 480p, 720p or 1080p. Video edits keep the source video length. 2K and 4K are not supported.
• One task can use up to 30 images, 10 videos and 10 audio clips as references, and audio alone can serve as the reference.
• The smart workflow is a 480p draft first, then a 1080p final with the same prompt, assets and length.
• Billing is per second and by resolution tier, reference video length also counts, and failed or moderation-blocked tasks are fully refunded.

Step 1: Set Up Your APIMart Account and Key

Sign up on APIMart, then open the Seedance 2.5 page and try a few prompts in the playground before you build anything. It is the fastest way to learn how the model responds to your style of prompt.

Create and Store Your Key Safely

When you are ready to call Seedance 2.5 from your own app, create an API key in the APIMart dashboard. Keep it in an environment variable or a secrets manager, never in source code or a shared repository. If a key leaks, revoke it and create a new one right away, and use separate keys for testing and production so you can tell the two kinds of usage apart.

Step 2: Choose the Right Seedance 2.5 Mode

Everything else depends on the mode, so decide this first.

Text to Video, Reference Images, First and Last Frames, Video Edit and Extend

A single task can use up to 30 images, 10 videos and 10 audio clips as references. The reference videos together can run up to 30 seconds, and so can the reference audio. Seedance 2.5 also accepts audio alone as the reference, which helps when you want the visuals to follow a voice-over or a music track.

Write Prompts That Work

• Describe one continuous shot: who the subject is, what they do, how the camera moves, and what the light looks like.
• Refer to your assets in order, for example "the woman in image 1 holds the bottle from image 2", so the model knows which reference plays which role.
• Use the right verbs for edits: in an edit task, say what to add, remove or replace; in an extend task, say whether to extend forward or backward.
• Keep edit words out of normal tasks: in a regular reference task, avoid words like "edit", "remove", "replace" or "extend", or the task may be treated as an edit.
• Put spoken lines in quotes inside the prompt when you want dialogue, and leave audio on.

When to Use Seedance 2.5 vs Seedance 2.0, Fast and Mini

Choose Seedance 2.5 when you need clips longer than 15 seconds or more references than Seedance 2.0 allows. If a short clip has to be delivered in 4K, Seedance 2.0 is still the one that supports it.

Step 3: Set Length, Resolution and Audio, Then Generate

Outside video edit mode, set the clip length between 4 and 30 seconds, or let the model choose. If you leave it empty, Seedance 2.5 makes a 5-second clip.

For video edits, select automatic length and the adaptive aspect ratio. The source video must be 4–30 seconds long, and the output keeps its length; a fixed output length is not supported.

Pick one of seven aspect ratios (16:9, 4:3, 1:1, 3:4, 9:16, 21:9 or adaptive); adaptive is the default and matches your source material. Audio is generated by default and can be turned off when you plan to add your own sound. Output is MP4 by default, and MOV is available when you need higher color precision for editing or extending.

Start with a 480p Draft, Finish at 1080p

Turn on draft mode to get a 480p preview first. If the motion, pacing and framing look right, produce the 1080p final from that draft within 7 days, keeping the prompt, assets and length the same. This way you only pay for 1080p once you know the shot works.

Review the Result and Save It Promptly

Generation runs in the background. After you submit a task, you get a task ID and check its status until it is done; how long it takes depends on clip length, resolution and how many references you use. When the clip is ready, review it and save a copy.

Step 4: Fix Common Problems and Keep Costs Down

Common Errors and How to Avoid Them

• 2K or 4K is rejected: Seedance 2.5 only supports 480p, 720p and 1080p. Use Seedance 2.0 if you need 4K.
• The task fails in first-frame, edit or extend mode: these modes only work with the adaptive aspect ratio. For video edits, also select automatic length; setting a fixed length will cause the task to fail even with the adaptive aspect ratio.
• A normal reference task is treated as an edit: remove words like "edit", "remove" or "replace" from the prompt.
• A real-person photo is blocked: real faces must be uploaded to the asset library and approved before use. Passing an image link directly will be rejected.

Billing is per second and by resolution tier, and when you use reference videos, their length counts too. Failed tasks and tasks blocked by content moderation are fully refunded, so you only pay for clips that are actually produced. To keep costs down, draft at 480p, keep clips as short as the shot allows, and only produce the 1080p final once the draft looks right. Current prices are on the Seedance 2.5 page.

Conclusion: From First Prompt to Finished Clip

Start in the playground, pick the mode that fits your material, draft at 480p and finish at 1080p. When you want to call the model from code, the Seedance 2.5 page has code samples and a parameter table, and the Seedance 2.5 documentation covers every option in detail.

FAQs

How long does Seedance 2.5 take to finish a video?

Seedance 2.5 can generate one continuous clip up to 30 seconds long. Tasks run in the background: you submit a task, get a task ID, and check the task status until the video is ready.

How long it takes depends on clip length, resolution and how many references you use.

What should I do if my video URL expires before I download it?

If the result link no longer opens, check the task history to see whether the video is still available to download. If you still cannot retrieve it, contact APIMart support.

Download the video or save a copy in your own storage as soon as the task finishes. Do not rely on the result link as your only backup.

How can I avoid duplicate charges when retrying failed requests?

Failed tasks are fully refunded, and you are only charged when a clip is actually produced. Duplicate charges happen when the same request is submitted twice and both succeed.

Before you retry, check whether a task for the same request already exists. If it does, keep checking that task instead of submitting a new one.