An animated image is a useful starting point. For a more deliberate video, the questions become more specific: Can I use my own product photo? Can a reference clip guide the camera movement? Can I decide how the shot begins and ends?
This guide walks through the two Kling 4.0 modes currently available through ModelFold: Reference to Video and Keyframe to Video. It includes the actual input images and an existing output example, followed by a simple workflow for your first clip.
Disclosure: I work on ModelFold, which provides access through an upstream provider. This is a guide to our current integration, rather than an independent benchmark. The example below was already available on our model page; I did not run a new generation for this article.
What is available today?
ModelFold currently offers 720p and 1080p output, durations from 3 to 30 seconds, and synchronized audio and video generation. Plan around the options currently available on the model page: 4K and HDR are marked as upcoming there.
Kling 4.0 is developed by Kuaishou. This article introduces access through ModelFold; it does not claim an exclusive launch or access ahead of the official release. For the developer's own overview, see Kling AI's production examples.
The practical choice is how you want to guide a shot.
Reference to Video: give each input a clear role
Use this mode when existing images or video should inform the result.
For example, the prefilled example on our model page uses a reference video to guide camera movement and pacing, with separate images for a car and its background. The useful idea is to separate the roles of the inputs before writing the prompt:
- Subject: what object or character should appear?
- Setting: where should the action happen?
- Camera: what movement and pacing should the clip follow?
Explain those roles in the prompt. A collection of references gives the model more material, but clear instructions are still needed to say how the pieces belong together.
Keyframe to Video: decide the beginning and ending
Use this mode when the composition at particular points matters most. It supports a first frame, intermediate frames, and a final frame.
The maximum is 10 keyframes, but the limit also depends on clip duration. For example, a five-second clip supports up to six frames; the full 10-frame allowance starts at nine seconds. Check the duration-specific limit before preparing a large set of images.
One useful application is a process with a clear beginning and result. The existing blacksmith example illustrates this approach.
A real input-to-output example: iron stock to a finished sword
These two images and the video are paired together in ModelFold's existing Keyframe to Video example. They were not selected from unrelated assets.
First frame: five pieces of iron on a workbench.
Final frame: the finished sword on the workbench.
Output: an approximately 15-second blacksmithing sequence.
Watch the existing generated video, or open the Kling 4.0 model page to view the paired example.
The example prompt divides the process into stages: collecting the material, heating, forging, grinding, assembly, and placing the finished sword. It asks for one blacksmith throughout, a consistent workbench setting, and compositions that match the opening and closing images.
Those are prompt goals. When reviewing the result, compare the starting and ending compositions, then inspect the transitions and action continuity. Do not assume that every requested physical detail has been reproduced accurately.
The linked preview is the original display file: approximately 15 seconds at 850 × 480, with an audio track. Its dimensions describe that preview asset, not the selectable resolution for a new generation.
Your first clip: a simple workflow
- Open the ModelFold Kling 4.0 page and sign in or register. You can use the web Playground directly; create an API key only if you need programmatic access.
- Choose Reference to Video for a shot guided by existing visual references, or Keyframe to Video when you want to specify the opening and ending images. Look at the paired input and output example first.
- Begin with 720p and three or five seconds. Keep the subject, action, and camera movement simple so the result is easier to assess.
- Replace the prefilled example materials. Remove any images, videos, and prompt references that do not belong in your own clip.
- Review the settings and displayed cost before running the task. Inspect the result before increasing duration or resolution.
A small starting prompt could be:
A ceramic mug sits on a wooden table. The camera slowly moves closer. Soft daylight enters through a nearby window. Quiet indoor ambience.
This is a suggested prompt, not a tested output from this article. Change one part at a time so you can tell which adjustment helped.
When to use the API
The Playground is a convenient place to inspect examples and explore basic settings. Some complex nested parameters for subjects and voices are not fully exposed in the current web form. If you need those controls, consult the API documentation for the selected mode.
For a product clip, storyboard preview, or image-to-video experiment, start with one clearly defined shot. Decide what your references control, keep the first attempt short, and evaluate the output before building a longer sequence.
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