arkennemasis fal · Seedance 2.5 US Text to Video · $0.26-1.40/s

Seven widgets, one text box, one video out. If you're new to the arkennemasis fal shelf, start here - not because it's the most capable Seedance node (that's the reference-to-video one) but because it's the only one where there's nothing to get wrong before you hit Run. No picture to upload, no @Image1 numbering, no task mode that rewrites your other settings.

What you get back is a single sustained shot with native audio, 4 to 30 seconds long, at up to 1080p. One prompt, one shot, sound included. For an establishing shot, a b-roll plate, or a title sequence, that's the whole job.

How it works

It's an API wrapper, in the plainest sense: no model on your machine, no weights, nothing to download. Seedance is ByteDance's closed video line and it has never been released in any other form, so a node is the only way it was ever going to reach a ComfyUI canvas. The node reads FAL_KEY from your install's .env, checks every input, estimates the cost, submits one request to fal, polls while showing status, and downloads the result into output/fal/bytedance_seedance-2.5_us_text-to-video/. Because there's no connected media, there's nothing to upload first - the run is one billed POST.

The inputs that matter

• prompt - the only creative input. Describe the shot, the camera move, and the light; the model reads it as a whole rather than scene by scene.
• resolution - 480p, 720p, 1080p. Roughly $0.26, $0.57 and $1.40 per second of output on this US-hosted endpoint.
• duration - auto, or 4 through 30 seconds. Pin it. auto is a nice idea and a terrible budgeting habit.

The rest are set-and-forget: aspect_ratio (auto, 21:9, 16:9, 4:3, 1:1, 3:4, 9:16), generate_audio - which costs the same whether it's on or off, per the node's own tooltip, and gives you effects, ambience and lip-synced speech - plus bitrate_mode (standard or high) and codec (auto, H264, H265).

Outputs are video, video_path, seed, draft_id and info. draft_id sits empty here: this endpoint has no draft mode, unlike the non-US text-to-video node which has a draft switch and a 480p preview rate. Everything you need to know about a run afterwards - request id, estimate, the files written - is in info.

The US thing

There's a cheaper twin of this node in the same folder, the non-US Seedance 2.5 Text to Video at $0.22–1.16/s against this one's $0.26–1.40/s. Same model, same widgets. If region routing isn't something you actually need, the other one is roughly 15% cheaper per second of video and worth the click. If it is something you need, you already know why you're here.

Install

Manager → search comfyui-arkennemasis, or:

cd ComfyUI/custom_nodes
git clone https://github.com/Hishamahmer/comfyui-arkennemasis

Restart ComfyUI, then add FAL_KEY=your-key-from-fal.ai/dashboard/keys to the .env in the folder with run_nvidia_gpu.bat (the node also checks the ComfyUI folder itself, and nothing else). Only httpx is in the pack's requirements, and only the Codex/ChatGPT-login nodes need it - the fal provider talks to fal with the standard library.

Common issues & troubleshooting

Straight to a "no FAL_KEY" error. The message names the exact .env path it read. That's the whole fix.

"Estimated cost is above max_cost_usd." The default cap is $20 and 30 seconds at 1080p is about $42, so the node refuses before it sends anything. Shorten, downscale, or raise the cap. 0 turns it off; think before doing that.

The same clip came back instantly. reuse_identical_run is on by default and found the previous, paid-for result in output/fal. Turn it off when you want a fresh roll, and leave it on when you're re-running a graph to test the wiring.

Nothing seems to be happening for two minutes. That's the model working; long runs poll with no fixed timeout and the node shows queue position, elapsed seconds and the estimate while it waits. Cancel in ComfyUI cancels the request on fal too.

ComfyUI crashed mid-run. The job continued on fal's side. Take the request id from output/fal/_requests.jsonl and use the pack's fal Recover Result node to download it, free.