Kling 4.0 Edit

Endpoint

POST https://api.roasos.com/v1/video-edit/kling-4

Send your API key as a bearer token. The key needs the scope api:write. Every paid request also needs an Idempotency-Key header.

The envelope fields quote_only, quote_id, webhook_url and wait_timeout_seconds behave the same on each model endpoint. Refer to Jobs and Quotes and credits.

Good at

Kling 4.0 Edit is the only Kling edit model since 2026-10-29. It replaced the Kling O3 edit endpoints, and those endpoints are removed.

Use it to replace a person or a product in footage that you own, to change the setting, or to change the look. The source video must be 3 to 30 seconds long and at least 700 px on each side. The prompt names the source as @Video1. Send references (up to 10 images, named @Image1..N) for looks and products. Send elements (up to 7, each a frontal image and 1 to 3 more views, named @Element1..N) to put an exact person or product into the video. Send avatar_id to use a saved person as an element, and product_id to add the product's kit images as references.

The output length is duration_seconds when you send it. Otherwise it is the length of the source, rounded to a whole second.

Pricing

The unit is one source_second. Pricing key: kling-4.

The credits come from the roasOS pricing table. No other field changes the price. To get the exact price of your request, send it with quote_only: true first.

Modes

• edit

Provider endpoints: kling/v4/video-to-video/edit.

Request fields

The schema is strict. A field that is not in this table gets 400 unsupported_option. The field names are the roasOS role names. One role has one name in every family.

Media

This endpoint accepts these media roles:

• avatar_id — identity; the saved character reference sheet, with a derived portrait only where the model requires a single face or source frame
• elements — identity; one frontal image plus more views, per person or object
• product_id — product; resolves to the product image list
• references — style and appearance references
• video_url — the source video

Every other role is refused: product_images, reference_images, image_url, end_image_url, scene_id, scene_image, video_urls, audio_urls, audio_url, voice_id. A refused role gets 400 unsupported_option.

Prompt

Limit 2,500 characters.

• Write only the change: "Replace the person with @Element1. Keep the camera, the cuts and the timing of @Video1."
• Use each @Image and @Element tag once. The platform adds a missing @Video1 or @Image tag at the end. You must write each @Element tag yourself.
• Ask for the existing text in the video to stay, unless you want it removed.
• Do not ask for a new shot plan. The source sets the shots.

Not exposed

These catalog entries describe omitted inputs, pinned values and source constraints. They do not imply that the provider accepts every listed field.

• video_url — these values are not available: MOV containers.
• video_urls — not accepted by this public endpoint.
• voice_ids — not accepted by this public endpoint.

Result

The result kind is video. Always present: url.

{
  "data": {
    "id": "gen_…",
    "kind": "video",
    "model": "kling-4",
    "status": "completed",
    "result": {
      "url": "https://cdn.roasos.com/workspaces/ws_01/result"
    }
  }
}

The files are immutable objects on https://cdn.roasos.com. A result URL is a valid media input for your next request.

Example

The three steps are always the same: quote, run, poll.

# 1. Quote. Nothing is spent.
curl -X POST https://api.roasos.com/v1/video-edit/kling-4 \
  -H "Authorization: Bearer roasos_sk_live_..." \
  -H "Idempotency-Key: 0f1c9e2a-kling-4-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_only":true,"prompt":"A woman holds the bottle at eye level in a bright kitchen, morning light, static camera.","video_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/video_url.mp4"}'
# 200 { "data": { "kind": "quote", "quote_id": "q_7Hk...", "credits": 12, "expires_at": "...",
#        "confirmation": { "model": "kling-4", "example": "5s_source_720p" } } }

# 2. Run. Same body, same Idempotency-Key, quote_id in place of quote_only.
curl -X POST https://api.roasos.com/v1/video-edit/kling-4 \
  -H "Authorization: Bearer roasos_sk_live_..." \
  -H "Idempotency-Key: 0f1c9e2a-kling-4-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_id":"q_7Hk...","prompt":"A woman holds the bottle at eye level in a bright kitchen, morning light, static camera.","video_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/video_url.mp4"}'
# 201 { "data": { "id": "gen_...", "status": "queued", "credits_reserved": 12 } }

# 3. Poll, then read the result.
curl https://api.roasos.com/v1/jobs/gen_.../status -H "Authorization: Bearer roasos_sk_live_..."
curl https://api.roasos.com/v1/jobs/gen_.../result -H "Authorization: Bearer roasos_sk_live_..."

See also

• llms.txt for this model — the same facts as one plain-text file for an agent.
• GET https://api.roasos.com/v1/catalog/kling-4 — the machine-readable form: enums, defaults, limits and prices. Refer to the API reference.
• Jobs — how to poll a job and read its result.
• Provider endpoints: kling/v4/video-to-video/edit.