Kling 4.0 Review: 30-Second Clips with Sound, Filtered Content

The gallery holds the six published examples from the Kling 4.0 model page, two per task, at 720p and 5 seconds. All show clothed adults, and none is a content-test clip.

Text-to-video, two framings. An astronomer opens an observatory dome and says a quiet line under a band of dusk sky; the model chose two camera angles for one paragraph. A vertical highway shot follows a pickup arriving, a man lying back in the truck bed and a tilt up to a brightening Milky Way: three beats in five seconds.

Image-to-video, with and without a closing frame. A man at a gas station keeps his face, jacket and car from the opening frame while the lamp flickers on. In the second example the opening and closing frames share a camera position, and the clip walks the astronomer from the telescope to the railing.

Reference-to-video. @Image1 is a woman and @Image2 a chrome trailer; both appear as the references show, and the model added string lights and a closing face shot. The second example casts a man from a portrait onto a motorcycle from a product photo and keeps the jacket, beard, tank and headlight.

Other checks. A 3-second clip with an opening, a middle and a closing frame passed through all three. A reference clip's action was reproduced almost frame for frame when the prompt described it. A 1080p 21:9 clip measured 2200 x 940, and a 1080p clip following a 16:9 reference video came back 1920 x 1080.

Write in the order things happen: subject and wardrobe, action, one camera move, then a separate Sound line. Put spoken words in quotes. For image-to-video, describe only the motion; the frame already shows the look. For reference-to-video, open with a cast list ("@Image1 is the woman, @Image2 is the chrome trailer"). Draft at 720p and 3 to 5 seconds before paying for 1080p or a long take.

1. Text-to-video, an establishing shot with a spoken line. aspect_ratio 16:9, duration_seconds 5.

Inside a white observatory dome on a high-desert mesa at indigo dusk. An astronomer in her late thirties with short silver-streaked hair, wearing a charcoal wool sweater and fingerless gloves, turns a heavy brass wheel; the dome slit slides open and a band of deep-blue sky full of first stars pours light across the telescope. She looks up and says quietly, "There you are." Slow crane up from her hands on the wheel to the opening sky. Sound: the grinding rumble of the dome, cold wind, a faint motor whirr.

Run this prompt on Kling 4.0 →

2. Reference-to-video, a person and an object. Two images in reference_image_urls, the person first, then the object.

@Image1 is the man, @Image2 is the motorcycle. On a dusty desert highway shoulder at indigo dusk, the man from @Image1 walks up to the chrome café-racer from @Image2, swings a leg over and kicks it into life; the round headlight flares on and lights the drifting dust. Low tracking shot circling from the front wheel to his face. Sound: footsteps on gravel, the kick-start, a throaty engine settling into idle, wind.

Run this prompt on Kling 4.0 →

Weak: a long list of keywords and no order of events. Strong: one paragraph in the order it happens, with the sound described on its own line and "one continuous shot, no cuts" if you want a single take.

Kling reviews requests itself, so SpicyAPI adds no filter of its own on top; the page label is Filtered. On 16 October 2026 we sent two text-to-video requests, one at Moderate and one at Very strong, and both were refused after about 2.5 seconds with "Content flagged as potentially sensitive". No video was rendered and nothing was charged. Readings are delivered / toned down / refused.

That is a small sample, and we did not test Mild, Strong or Maximum on Kling 4.0, nor any content request on image-to-video or reference-to-video. Kling 3.0's earlier results are a fair guide: there Mild requests rendered, every Moderate and stronger request was refused, and Kling checked the prompt, any upload and the finished clip. We have no evidence that 4.0 differs, and no refusal has ever been billed.

Adults only, in every prompt, upload and output. Never depict a real, identifiable person without their consent, and make sure you hold the rights to any photo or clip you upload.

• Wider content limits on video? Seedance 2.5 and Seedance 2.5 Spicy are our picks when the brief needs more than Kling accepts; see the Seedance 2.5 review and the Seedance 2.5 Spicy review.
• A low-cost draft? Wan 3.0 and Wan 3.0 Spicy run at a lower price per second; see the Wan 3.0 review.
• Shorter clips for less? Kling 3.0 costs less per second and adds Motion Control, but stops at 15 seconds and is filtered the same way. See the Kling 3.0 review.