ByteDance First-Last-Frame to Video

ByteDance's answer to "make the video end the way I want" is the same shape as Google's and Kling's: pin the first frame, pin the last frame, and let the model animate the middle. This node is the Seedance first/last-frame API, built into ComfyUI core - no install, and it runs on ByteDance's servers through Comfy's proxy rather than your machine.

The mechanics are straightforward. first_frame and last_frame are the anchors, prompt is what you want to happen between them, and the node uploads both images, wraps everything up with the resolution/ratio/duration as command-line-style flags, and polls until a VIDEO lands on the output. The model dropdown is where you choose your tier: seedance-1-5-pro-251215 (the newest pro model, with audio support), seedance-1-0-pro-250528, or the default seedance-1-0-lite-i2v-250428 - the cheap tier that's fine for drafts. Yes, the default is the lite model, which is a sensible way to not bleed credits on your first runs.

The controls you'll actually touch: resolution (480p/720p/1080p), aspect_ratio (including an adaptive option that lets the model pick), and duration - a slider from 3 to 12 seconds, with a real caveat: Seedance 1.5 Pro enforces a minimum of 4 seconds, so the 3-second setting only works on the older models. Then there's camera_fixed, a deceptively simple boolean. It appends an instruction to your prompt telling the camera to hold still - and the tooltip is admirably honest that it does not guarantee the effect. Treat it as a soft preference, not a lock. generate_audio is there too, but read the fine print: it's ignored for every model except seedance-1-5-pro. That's ByteDance quietly telling you audio is a pro-model feature.

Output is a single VIDEO. The image constraints are worth knowing before you fight them: frames must be 300–6000px on each side with an aspect ratio between 0.4:1 and 2.5:1 - a panorama or a near-square both work, a 1:10 banner doesn't. And watermark defaults to false; flip it if you need a visible "AI generated" mark.

Where this fits: anywhere you need a guaranteed ending. Two storyboard stills become a shot. A character's pose at the start and their pose at the end become a motion arc, with the identity pinned at both ends instead of hoped for. It's the same bookending trick as the Veo and Kling variants - pick whichever vendor's quality and pricing you like, because the workflow is interchangeable.

The usual partner-node caveats apply: it's paid per render through your Comfy account, your images get uploaded to ByteDance's servers, and there's a content filter on the other end that occasionally rejects things - a contents_moderation-style failure is the vendor's filter, not a broken graph. ByteDance's video API nodes have been in core since September 2025, with Seedance 1.5 Pro added in early 2026. Cheap tier first, pro tier when the shot's locked.