Stable Video Diffusion

Heads up before you drag this into a graph: despite the name, this isn't the free, local Stable Video Diffusion checkpoint that ComfyUI's own native SVD loader nodes run. Stable Video Diffusion here is a thin wrapper around Stability AI's hosted image-to-video API - the one at platform.stability.ai - which means a Stability AI account, an API key, and real credits spent on every run. If you were expecting to point this at a local .safetensors and get free generations forever, that's the exact mixup people run into with API-flavored nodes: "why is ComfyUI asking me to pay for credits" threads almost always trace back to a template that quietly used an API node like this one instead of a local model.

How it works

You hand it one image, it calls Stability's image-to-video endpoint, and you get a short clip back as a batch of frames. cfg is the usual classifier-free guidance strength on the generated motion. mbi is Stability's own SVD parameter - motion bucket index - the standard knob for how much movement to inject, higher meaning more motion. Stability's own reference examples tend to default this around 127; this node's default of 40 is noticeably tamer, so don't be surprised if your first result at defaults looks closer to a static shot with subtle drift than a dramatic pan.

The inputs and outputs that matter

• image (required, IMAGE) - your source frame.
• api_key (required, STRING) - from your Stability AI account dashboard. This node has no local fallback; without a valid key it does nothing.
• mbi (default 40, 1–255) - the one to raise if the motion feels too still.
• cfg (default 2.5) and seed - rarely need touching from defaults; seed for reproducibility.

Output is frames - a normal IMAGE batch, so anything expecting a batch downstream (Save Image, a video-combine node) just works.

How to install it

ComfyUI Manager: search SaltAI-Open-Resources or SaltAI, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/get-salt-AI/SaltAI

then restart. No local model download for this node specifically - the actual generation happens on Stability's servers, so it never touches your GPU or your models/ folder.

Common issues & troubleshooting

Auth errors. Almost always a bad or expired api_key, not a broken node. Check your Stability dashboard for the current key and, just as important, your remaining credit balance - a maxed-out balance fails the same way a bad key does.

Node seems to hang. Stability's hosted video endpoint has historically run async on their side (you submit, then poll for a result) - a slow response is their queue, not your local setup. There's genuinely nothing to debug on your end when this happens.

Unexpectedly high bill. Every run of this node spends real money against your Stability account. Don't leave it sitting inside a loop, or queue-batch it, while you're actually tuning something earlier in the graph - iterate on the cheap parts first and only run this once you're ready to spend the credit.