Runway Image to Video (Gen4 Turbo)

The fastest honest path from a single still image to a moving clip, using Runway's Gen4 Turbo model. You give it one starting frame and a prompt, it gives you a video that begins exactly there and goes wherever the prompt and the model decide. "Turbo" in the name is doing real work: Gen4 Turbo is Runway's speed-optimized tier, priced to encourage iteration rather than the slow, expensive flagship runs. If you want to actually test what a frame becomes as a video without watching your credits evaporate, this is the node.

It's an API node like every other entry in ComfyUI's built-in partner/video category: ships with ComfyUI core, uploads your start frame to Comfy Org's backend, calls Runway's Gen4 Turbo API on your behalf, and bills your Comfy account in credits. No local model, no GPU usage, no Runway account needed - your Comfy account is the billing surface.

The inputs that matter

• start_frame - the image the video begins from. This is the contract: the first moments of the clip should match it. Images up to 7999px are accepted, with an aspect ratio between 1:2 and 2:1.
• prompt - what happens next, plus anything you want to change about the frame as the camera moves. "The camera slowly orbits while she turns to the window" is the kind of direction this model handles.
• duration - a combo pick (Runway's preset durations). ratio - Runway's aspect ratio presets, which set the output shape.
• seed - random seed for generation; the usual family behavior of "change it to get a different take."

Output is a single VIDEO.

Where people get burned

• The node's own docs point to a best-practices page. The description links Runway's Gen-4 creation guide, and it's worth the read before you start: Gen 4 has opinions about what makes a good start frame, and a mediocre frame produces a mediocre clip no matter how good the prompt is.
• It's first-frame-anchored, not first-frame-guaranteed. The model interprets the frame as the scene's starting state, and prompt can override details as motion begins. If the clip immediately ignores something critical in your image, that's the prompt fighting the frame - simplify one or the other.
• Turbo is a quality/speed trade. It's faster and cheaper than the full Gen-4 experience, and the speed shows at the margins. Fine for drafts, iteration, and proof-of-concept; if you need the flagship finish, the same family has non-turbo options.

For quick first-frame-to-video, this is one of the friendliest built-ins in the whole category - and the "Turbo" pricing makes it the one you won't feel guilty experimenting with. Drop a good frame in, describe the motion, and see what comes back.