EvoLink Seedance 2.5 Image-to-Video (Official)

Seedance 2.5 I2V is the image-to-video member of the current gen, and its two upgrades over 2.0 are the ones you'll actually feel: clips run up to 30 seconds, and a smart-duration mode lets the model time the shot. EvoLink Seedance 2.5 Image-to-Video (Official) is the closed API wrapper - required first_frame, optional last_frame, prompt in, VIDEO out. Nothing runs locally, because nothing about Seedance is downloadable.

What it is

• first_frame (required) - the starting image from any image output. Local files upload through EvoLink's channel and are auto-deleted after 72 hours. The clip's aspect ratio follows this frame.
• last_frame (optional) - the ending image. Connect it and you're in first/last-frame mode; mismatched ratios auto-align to the first frame.
• prompt (required) - the motion description, Chinese welcome, ~500 chars.
• duration - 4–30 seconds, default 5, billed by duration.
• auto_duration - the smart knob: it overrides duration and lets the model pick a length in the 4–30 range, billed on what it actually outputs.
• quality - 480p / 720p / 1080p. Note the top is 1080p; the 2.5 line dropped the 4K option that 2.0 I2V still has.
• generate_audio - on by default, no extra cost.

Outputs: video (into Save Video - nothing visible otherwise), task_id, status_info, result_urls (24-hour expiry), response_json. Default timeout 30 minutes; a long I2V render is a genuinely long wait.

Install and key

Shared EvoLink install. ComfyUI Manager → search EvoLink → install → full restart (close the console window, not just refresh the tab). Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/deeplearning-goethe/comfyui-evolink

Dependency is just requests; no models, no GPU. Key from evolink.ai/dashboard/keys (sk-), pasted once - saved locally, blank after, never in a shared workflow JSON.

How to get the most out of it

The first/last-frame mode is the real editorial tool here, and 30 seconds makes it more useful: with a 5-second budget, first/last-frame was a tiny loop; at 30 seconds it's a scene with an arc. Use the loop trick (last frame = first frame) for long, seamless cycles, or pick a genuinely different end frame for a transition that has to physically resolve.

The one honest frustration is the resolution ceiling: if your hero frame deserves 4K motion, 2.5 I2V caps out at 1080p and you'll be eyeing the 2.0 I2V node instead. Otherwise the standing Seedance math applies - metered per render, prompt and frames leave the machine, drafts are cheaper on Fast/Mini or at 480p, and failed or moderation-blocked tasks don't charge. It's a great video node; just don't let it surprise you into a big bill.