arkennemasis fal · Flux 3 Text to Video Draft · $0.06/s

Full-quality FLUX 3 video is $0.17–0.29 per second. A 15-second shot at 1080p is over four dollars, and if the motion is wrong you've paid four dollars to find that out. The draft endpoints exist to make that mistake cheap, and they're the single most useful thing in this corner of the pack.

ArkFal_blackforestlabs_flux_3_text_to_video_draft renders at $0.06 per second - roughly a fifth of the 720p full render - and hands you back a reusable draft cache. That cache is the whole point: feed it to draft_enhance and the finish is a re-render of this draft, same seed and motion, no re-planning. Five drafts and one finish costs less than two full renders.

What you set

• prompt - the draft prompt. Nothing changes between draft and enhance except quality, so write the real one here.
• duration - whole seconds, 5 through 20, or auto to let the model decide. Everything is billed by the second, so this is the cost dial.
• generate_audio - on by default. Drafts include audio, which is genuinely useful for checking whether a line of dialogue lands, and costs nothing extra.
• aspect_ratio - auto by default.
• safety_tolerance - 0 to 4, default 2, same as the full node.

Note what's not here: a resolution box. Drafts are 720p-class by definition. That's the deal.

Optional, and shared with every fal node in the pack: max_cost_usd (default $20 cap, enforced before anything is uploaded or sent; 0 disables), reuse_identical_run (default on - identical inputs come back from disk without a second charge, including after a ComfyUI restart), extra_json, max_concurrent.

Outputs: video, video_path, draft_cache_path (the local file for the encrypted bundle), and info.

The handoff that trips people up

draft_cache_path is a local file. The enhance node wants draft_cache_url, a URL. Those are not the same thing, and the text in that box goes to fal verbatim - fal cannot read your output/fal/ directory.

The bundle's fal URL is inside the draft node's info output (it carries fal's full answer, including the draft_cache file object), and it's also written to output/fal/_requests.jsonl when the draft completes. Grab it from there and paste it into draft_cache_url on the enhance node. Keep that info around until the finished clip exists - a draft without its URL is a paid preview you can't upgrade.

Also worth knowing: the draft's own video output is a perfectly good thing to look at in ComfyUI. It's the review tool; the enhance is the delivery.

Install

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

ComfyUI Manager works too - search arkennemasis, install, restart. Then the key:

FAL_KEY=your-key-from-fal.ai/dashboard/keys

in the .env next to run_nvidia_gpu.bat (portable) or in your ComfyUI folder. No key field on the node, and nothing to download - FLUX 3 only runs on fal, which is the entire reason this node exists as a wrapper.

Where people get burned

The estimate shown in the browser can't know what auto duration will return, so it shows a rate; the real dollar figure appears at run time. If you want a number you can trust before running, set duration explicitly.

Because reuse_identical_run is on by default, tweaking anything - even adding an unused upstream node - changes the run hash and bills you again, while re-running the exact same graph won't. That's the behaviour you want, but it means "same settings, new take" is a lie unless you turn the toggle off.

Results land in output/fal/blackforestlabs_flux-3_text-to-video_draft/. Failures before the submit step - bad inputs, a missing key, an estimate above your cap - cost nothing, because the node checks all of that before it uploads or sends anything.