Kling 3 Motion Control

Endpoint

POST https://api.roasos.com/v1/video/kling-3-motion

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

The reference image supplies the character, the background and the other visible elements. The reference video supplies the body motion and, with character_orientation: "video", the camera behaviour. Use it for dance, gesture and presenter moves that must match a source clip exactly. The standard tier is the cost-effective mode for portraits and simple animations; the pro tier is the choice for full-body motion and detailed clothing. Write the prompt about the subject, the wardrobe, the expression and the style, not about the camera, because the reference video already owns the camera. Keep the reference video short: it decides both the output length and the price. It is the only video model on roasOS that takes a reference video as its motion source, and the only one that requires a recorded media-rights attestation. It does not accept a text-only or image-only request, a last frame, or audio input.

Pricing

The unit is one clip. Pricing keys: kling-3-motion-pro, kling-3-motion-standard.

The catalog has no credit example for this model. Send quote_only: true to get the price.

Modes

• motion-control

Provider endpoints: fal-ai/kling-video/v3/pro/motion-control · fal-ai/kling-video/v3/standard/motion-control.

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:

• image_url — first frame (or the single source image)
• scene_id — first frame — a scene this workspace owns
• video_url — the source video

Every other role is refused: avatar_id, elements, product_id, product_images, references, reference_images, end_image_url, scene_image, video_urls, audio_urls, audio_url, voice_id. A refused role gets 400 unsupported_option.

Prompt

• Limit: 2,500 characters. No roasOS wrapper; the prompt goes verbatim, or the field is omitted when empty.
• No tags: @Element1 exists at fal only with elements, which roasOS does not expose.
• Craft: name the subject and the wardrobe ("woman in a red linen dress, hair tied back"), the expression ("calm, small smile"), and the style ("natural daylight, realistic skin"). Do not describe camera moves or the motion itself; the video owns both. Keep it short: the image and the video carry the information.

Not exposed

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

• duration_seconds — pinned to measured from video_url.
• aspect_ratio — not accepted by this public endpoint.
• resolution — pinned to named by tier.
• generate_audio — not accepted by this public endpoint.
• negative_prompt — not accepted by this public endpoint.
• seed — not accepted by this public endpoint.
• references — not accepted by this public endpoint.
• elements — not accepted by this public endpoint.
• avatar_id — not accepted by this public endpoint.
• product_id — not accepted by this public endpoint.
• end_image_url — not accepted by this public endpoint.

Result

The result kind is video. Always present: url.

{
  "data": {
    "id": "gen_…",
    "kind": "video",
    "model": "kling-3-motion",
    "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/kling-3-motion \
  -H "Authorization: Bearer roasos_sk_live_..." \
  -H "Idempotency-Key: 0f1c9e2a-kling-3-motion-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_only":true,"character_orientation":"image","image_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/image_url.png","keep_original_sound":false,"media_rights":{"accepted":true,"statement_version":1},"video_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/video_url.mp4"}'
# 200 { "data": { "kind": "quote", "quote_id": "q_7Hk...", "credits": ..., "expires_at": "...",
#        "confirmation": { "model": "kling-3-motion" } } }

# 2. Run. Same body, same Idempotency-Key, quote_id in place of quote_only.
curl -X POST https://api.roasos.com/v1/video/kling-3-motion \
  -H "Authorization: Bearer roasos_sk_live_..." \
  -H "Idempotency-Key: 0f1c9e2a-kling-3-motion-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_id":"q_7Hk...","character_orientation":"image","image_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/image_url.png","keep_original_sound":false,"media_rights":{"accepted":true,"statement_version":1},"video_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/video_url.mp4"}'
# 201 { "data": { "id": "gen_...", "status": "queued", "credits_reserved": ... } }

# 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_..."

The deprecated path

POST /v1/generations still reaches this model for one minor version. It is deprecated. This is how it maps:

Not available on the public API yet. POST /v1/generations returns 503 public_model_unavailable for model: "kling-3-motion", and the alias will stay refused because it cannot carry media_rights. The app reaches the model through its internal UGC route (image, referenceVideo, characterOrientation, keepOriginalSound, quality, rightsAccepted, rightsStatementVersion, rightsPolicyVersion); at v1.1 these become image_url, video_url, character_orientation, keep_original_sound, tier, media_rights{}. The agent does not offer this model.

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-3-motion — 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: fal-ai/kling-video/v3/pro/motion-control · fal-ai/kling-video/v3/standard/motion-control.