ComfyUI Node
arkennemasis fal · Flux 3 First Last Frame to Video · $0.17-0.29/s
FLUX 3 is Black Forest Labs' frontier video model. This endpoint generates the video between a defined start and end frame, interpolating a smooth, coherent transition from the first image to the last. Pricing (from fal, 2026-09-29): Your request will be charged at 0.17 $ per second of generated video at 720p, and 0.29 $ per second at 1080p. Model page: https://fal.ai/models/blackforestlabs/flux-3/first-last-frame-to-video Key: FAL_KEY in the .env next to run_nvidia_gpu.bat. Results are saved in output/fal/blackforestlabs_flux-3_first-last-frame-to-video/.
arkennemasis fal · Flux 3 First Last Frame to Video · $0.17-0.29/s
- start_image
- end_image
- video
- video_path
- seed
- info
◄prompt►
◄aspect_ratioauto►
◄resolution720p►
◄duration5►
◄generate_audiotrue►
◄safety_tolerance2►
◄max_cost_usd20.0►
◄reuse_identical_runtrue►
◄extra_json►
◄max_concurrent1►
Categoryarkennemasis/fal/Video/Flux
Inputs (12)
| Name | Type | Default | Description |
|---|---|---|---|
| prompt | STRING | The text prompt describing the video you want to generate. | |
| aspect_ratio | COMBO | auto | Aspect ratio of the generated video. `auto` lets the model choose. |
| resolution | COMBO | 720p | Resolution of the generated video. |
| duration | COMBO | 5 | Duration of the generated video in seconds. An explicit duration is required to place the end frame. |
| generate_audio | BOOLEAN | true | Whether to generate audio for the video. |
| safety_tolerance | INT | 20–4 | The safety tolerance level for the generated video. 0 is the strictest and 4 is the most permissive. |
| start_image | IMAGE | URL of the image used as the first frame of the video (PNG, JPEG, or WebP). | |
| end_image | IMAGE | URL of the image used as the last frame of the video (PNG, JPEG, or WebP). | |
| max_cost_usdopt | FLOAT | 20.00–100000 | Safety cap. If the estimated cost of this run is above this many US dollars the node stops BEFORE sending anything to fal. 0 = no cap. |
| reuse_identical_runopt | BOOLEAN | true | If these exact inputs (the settings AND the same pictures/clips/audio) were already paid for and the files are still in output/fal, return them instead of paying again - also after a ComfyUI restart. Turn off for a fresh take with the same settings. |
| extra_jsonopt | STRING | Advanced: a JSON object merged into the request last, for any fal field this node has no box for. Example: {"seed": 7}. Leave empty normally. | |
| max_concurrentopt | INT | 11–32 | How many paid fal calls may run at the same time in one run, across every fal node. 1 (default) = one after another. This node starts its paid part only while fewer than this many fal calls are running. Once any fal node fails, the ones still waiting are not started, so nothing more is billed. |
Outputs (4)
| Name | Type | Description |
|---|---|---|
| video | VIDEO | — |
| video_path | STRING | — |
| seed | INT | — |
| info | STRING | JSON: request id, cost estimate, saved files and fal's full answer. |