Bytedance Seedance 2.5 Image-to-Video

Seedance is ByteDance's flagship video line, and it is, as ever, API-only - the company that happily open-sources its components keeps its video products firmly behind a paywall, and Seedance is one of the closed models the open community measures itself against. This node is the hosted door into it via WaveSpeed, and what you get on the other side is the longest, highest-resolution video generation in this whole pack: 4–30 second clips up to 4k, with native synchronized audio if you want it.

Where the MiniMax H3 nodes cap out at 768p and 15 seconds, Seedance 2.5 Image-to-Video runs up to 30 seconds and 4k. It's the "actually make the shot" node, and it's the expensive one - the resolution tooltip spells it out: roughly $0.18/second at 480p all the way to $1.80/second at 4k. A 10-second 4k clip is a double-digit-dollar experiment. Start at 480p or 720p to find the look, then spend on the hero take.

How it works

Same shape as the rest of the WaveSpeed video nodes: hand it media, it sends a request, polls every 10 seconds (with a 30-minute timeout - the longest in the pack, because these jobs run long), and returns a URL.

Image input comes two ways. start_frame (IMAGE tensor) is preferred and takes precedence, sent to WaveSpeed as a base64 data URI; start_frame_url (STRING) is the fallback when nothing's connected. There's also an optional last_frame / last_frame_url - an ending frame that steers the clip toward that image. Note the word "steer": unlike MiniMax H3's two-frame interpolation, this is guidance, not a hard morph.

The model dropdown has three tiers, and the third is the interesting one: Seedance 2.5, Seedance 2.5 Turbo (faster), and Seedance 2.5 Spicy - tuned for high-volume generation, i2v only. If you're batch-producing a lot of clips, Spicy is the tier aimed at you.

Inputs that matter

• prompt - required, the motion description.
• model - standard, Turbo, or Spicy.
• duration - 4–30s, default 5.
• resolution - 480p / 720p / 1080p / 4k. See the price note above; this is where the money goes.
• generate_audio - default on. This one's worth actively thinking about: if you only need motion, flip it off and you're not paying for a soundtrack you'll discard. When it's on you get native audio synchronized with the video.
• seed - cache control only. Seedance 2.5 takes no API seed, so this is never sent. Fixed seed reuses the video you already paid for; -1 generates again on every queue.

Output is video_url (STRING), wired into Preview Anything for preview/download.

Installing and configuring

Part of the ERPK Collection pack. ComfyUI Manager: search erpk, install ERPK Custom Nodes, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/eRepublik-Labs/comfyui-nodes-erpk.git erpk
cd erpk && pip install -r requirements.txt

Then a WaveSpeed API key from wavespeed.ai into Settings > ERPK > API Keys (right-click canvas > ERPK Settings). No models, no VRAM - the API does the heavy lifting.

Common issues

• "It's been running for ages" - yes. The 30-minute timeout is real, and long 4k jobs legitimately take minutes. It's polling, not hung; leave it.
• The bill at the end of the month - 4k at $1.80/s is the headline number, but generate_audio defaulting on also adds cost to every clip. Turn it off for motion-only tests.
• Output aspect looks wrong - i2v output follows the source image's aspect ratio. If you feed a square frame, don't expect a 16:9 clip; crop/resize the start frame first.