Kling 4.0

Kuaishou · ~4 min

from $0.182per second

Kling 4.0 by Kuaishou: one model for text, frames (up to 10), photo/video/audio refs, edit and extend. 3–30 s, 720p or 1080p, always stereo.

Kling 4.0 is Kuaishou's flagship video model. One model instead of separate modes: clips from text, from the first and last frame plus up to 8 mid keyframes (up to 10 images total), from references (up to 10 photos, 5 videos, 3 audio clips), edit of an existing video, or extend from the last frame.

Duration 3 to 30 seconds, 720p or 1080p, aspects 16:9 · 9:16 · 1:1 · 21:9 or auto. Sound is always stereo: «auto» generates new audio, «origin» keeps your clip's sound.

You pay per second of the clip (with a video reference or edit — at the input rate). Failed generations are refunded.

One model, kling-4.0 · ~4 min. The result follows the input fields (prompt, frames, references, video_mode, duration) — there are no separate «animate / edit» endpoints.

Price

Resolution	Price per second	With your video, per second
720p	$0.182	$0.182
1080p	$0.273	$0.273

Price = per-second price × clip length, rounded up to $0.001. Charged when the task is created and fully refunded if it fails.
With your video, the seconds of the source clip are added to the seconds of the result.

Media limits

Type	Limits
Images	up to 10; JPG / PNG / WebP; upload via files/upload — up to 30 MB per file
Videos	up to 5; total ≤ 30 s (each clip 2…30 s); MP4 / MOV → MP4 on the server; upload ≤ 200 MB
Audio	up to 3; total ≤ 30 s; MP3 / WAV; upload ≤ 200 MB

Photos — public https or upload; video and audio — files/upload only.

Parameters (field `input`)

Parameter	Description	Values (default in bold)
`prompt`	What happens in the clip: scene, motion, camera, light, style	text, up to 2500 chars
`first_frame_url`	First frame: a photo link (https); the video starts from it	`"https://…"`
`last_frame_url`	Last frame (optional, only together with the first one)	`"https://…"`
`image_urls`	Reference photos (https)	`["https://…"]`, up to 10
`video_urls`	Your videos (MP4): upload them via files/upload first and pass the returned links	`["https://…"]`, up to 5
`audio_urls`	Audio (MP3): upload via files/upload first	`["https://…"]`, up to 3
`video_mode`	Task type for your video: `auto` (default) — the model works it out from the description, `reference` — reference, `edit` — edit (length and aspect ratio follow your video), `extend` — extend. Omitted = `auto`	`auto` · `reference` · `edit` · `extend`
`resolution`	Video resolution	`720p` · `1080p`
`aspect_ratio`	Aspect ratio	`16:9` · `9:16` · `1:1` · `21:9` · `auto`
`duration`	Video duration in seconds	3 to 30 (default `5`)
`audio_setting`	Sound	`auto` `origin`
`trim_video_to`	Trim each of your clips to N seconds: the beginning stays. Shorter clips are not changed	whole number, 2 to 30
`trim_to_duration`	Trim each of your clips to the chosen `duration`: the beginning stays. With `duration: "auto"` or `video_mode: "edit"` — to the model limit	`true` `false` (default `false`)
`auto_trim`	If your clips together are longer than 30 s, trim them instead of returning an error (the longest first)	`true` `false` (default `false`)

Examples

Prompt only

curl -X POST https://mixmedia.tech/api/v1/jobs/createTask \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"kling-4.0","input":{"prompt":"A drone flies over an autumn forest at sunrise, fog, cinematic","resolution":"720p","aspect_ratio":"16:9","duration":"5"}}'

import os, requests

r = requests.post(
    "https://mixmedia.tech/api/v1/jobs/createTask",
    headers={"Authorization": f"Bearer {os.environ['API_KEY']}"},
    json={
      "model": "kling-4.0",
      "input": {
        "prompt": "A drone flies over an autumn forest at sunrise, fog, cinematic",
        "resolution": "720p",
        "aspect_ratio": "16:9",
        "duration": "5"
      }
    },
)
print(r.json())  # {"code": 200, "data": {"taskId": "..."}}

const r = await fetch("https://mixmedia.tech/api/v1/jobs/createTask", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({
    "model": "kling-4.0",
    "input": {
      "prompt": "A drone flies over an autumn forest at sunrise, fog, cinematic",
      "resolution": "720p",
      "aspect_ratio": "16:9",
      "duration": "5"
    }
  }),
});
console.log(await r.json()); // { code: 200, data: { taskId: "..." } }

With a first frame

curl -X POST https://mixmedia.tech/api/v1/jobs/createTask \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"kling-4.0","input":{"prompt":"The character slowly turns to the camera, the wind moves the hair","first_frame_url":"https://mixmedia.tech/static/img/previews/gpt-t2i.jpg","resolution":"720p","duration":"5"}}'

import os, requests

r = requests.post(
    "https://mixmedia.tech/api/v1/jobs/createTask",
    headers={"Authorization": f"Bearer {os.environ['API_KEY']}"},
    json={
      "model": "kling-4.0",
      "input": {
        "prompt": "The character slowly turns to the camera, the wind moves the hair",
        "first_frame_url": "https://mixmedia.tech/static/img/previews/gpt-t2i.jpg",
        "resolution": "720p",
        "duration": "5"
      }
    },
)
print(r.json())  # {"code": 200, "data": {"taskId": "..."}}

const r = await fetch("https://mixmedia.tech/api/v1/jobs/createTask", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({
    "model": "kling-4.0",
    "input": {
      "prompt": "The character slowly turns to the camera, the wind moves the hair",
      "first_frame_url": "https://mixmedia.tech/static/img/previews/gpt-t2i.jpg",
      "resolution": "720p",
      "duration": "5"
    }
  }),
});
console.log(await r.json()); // { code: 200, data: { taskId: "..." } }

With references

curl -X POST https://mixmedia.tech/api/v1/jobs/createTask \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"kling-4.0","input":{"prompt":"A drone flies over an autumn forest at sunrise, fog, cinematic","image_urls":["https://mixmedia.tech/static/img/previews/gpt-t2i.jpg"],"resolution":"720p","aspect_ratio":"16:9","duration":"5","audio_setting":"auto"}}'

import os, requests

r = requests.post(
    "https://mixmedia.tech/api/v1/jobs/createTask",
    headers={"Authorization": f"Bearer {os.environ['API_KEY']}"},
    json={
      "model": "kling-4.0",
      "input": {
        "prompt": "A drone flies over an autumn forest at sunrise, fog, cinematic",
        "image_urls": [
          "https://mixmedia.tech/static/img/previews/gpt-t2i.jpg"
        ],
        "resolution": "720p",
        "aspect_ratio": "16:9",
        "duration": "5",
        "audio_setting": "auto"
      }
    },
)
print(r.json())  # {"code": 200, "data": {"taskId": "..."}}

const r = await fetch("https://mixmedia.tech/api/v1/jobs/createTask", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({
    "model": "kling-4.0",
    "input": {
      "prompt": "A drone flies over an autumn forest at sunrise, fog, cinematic",
      "image_urls": [
        "https://mixmedia.tech/static/img/previews/gpt-t2i.jpg"
      ],
      "resolution": "720p",
      "aspect_ratio": "16:9",
      "duration": "5",
      "audio_setting": "auto"
    }
  }),
});
console.log(await r.json()); // { code: 200, data: { taskId: "..." } }

With your video

curl -X POST https://mixmedia.tech/api/v1/jobs/createTask \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"kling-4.0","input":{"prompt":"Make the clip anime style, keep everything else","video_urls":["https://mixmedia.tech/files/<id>.mp4"],"video_mode":"edit","resolution":"720p","duration":"5","audio_setting":"auto"}}'

import os, requests

r = requests.post(
    "https://mixmedia.tech/api/v1/jobs/createTask",
    headers={"Authorization": f"Bearer {os.environ['API_KEY']}"},
    json={
      "model": "kling-4.0",
      "input": {
        "prompt": "Make the clip anime style, keep everything else",
        "video_urls": [
          "https://mixmedia.tech/files/<id>.mp4"
        ],
        "video_mode": "edit",
        "resolution": "720p",
        "duration": "5",
        "audio_setting": "auto"
      }
    },
)
print(r.json())  # {"code": 200, "data": {"taskId": "..."}}

const r = await fetch("https://mixmedia.tech/api/v1/jobs/createTask", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({
    "model": "kling-4.0",
    "input": {
      "prompt": "Make the clip anime style, keep everything else",
      "video_urls": [
        "https://mixmedia.tech/files/<id>.mp4"
      ],
      "video_mode": "edit",
      "resolution": "720p",
      "duration": "5",
      "audio_setting": "auto"
    }
  }),
});
console.log(await r.json()); // { code: 200, data: { taskId: "..." } }

Trim your video

Your clips together: up to 30 s. No need to cut a long clip beforehand:

trim_to_duration: true — trim each clip to the chosen duration;
trim_video_to: N — keep N seconds from the start;
auto_trim: true — if the clips together are over the limit, cut them exactly to it instead of an error.

Trimming is free, and the price uses the trimmed seconds — fewer seconds cost less.

curl -X POST https://mixmedia.tech/api/v1/jobs/createTask \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"kling-4.0","input":{"prompt":"Make the clip anime style, keep everything else","video_urls":["https://mixmedia.tech/files/<id>.mp4"],"video_mode":"edit","resolution":"720p","duration":"5","audio_setting":"auto","trim_to_duration":true,"auto_trim":true}}'

import os, requests

r = requests.post(
    "https://mixmedia.tech/api/v1/jobs/createTask",
    headers={"Authorization": f"Bearer {os.environ['API_KEY']}"},
    json={
      "model": "kling-4.0",
      "input": {
        "prompt": "Make the clip anime style, keep everything else",
        "video_urls": [
          "https://mixmedia.tech/files/<id>.mp4"
        ],
        "video_mode": "edit",
        "resolution": "720p",
        "duration": "5",
        "audio_setting": "auto",
        "trim_to_duration": True,
        "auto_trim": True
      }
    },
)
print(r.json())  # {"code": 200, "data": {"taskId": "..."}}

const r = await fetch("https://mixmedia.tech/api/v1/jobs/createTask", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({
    "model": "kling-4.0",
    "input": {
      "prompt": "Make the clip anime style, keep everything else",
      "video_urls": [
        "https://mixmedia.tech/files/<id>.mp4"
      ],
      "video_mode": "edit",
      "resolution": "720p",
      "duration": "5",
      "audio_setting": "auto",
      "trim_to_duration": true,
      "auto_trim": true
    }
  }),
});
console.log(await r.json()); // { code: 200, data: { taskId: "..." } }

One uploaded file: up to 30 s. Without these options, clips that are too long return a 400 error with a hint.

Create and result

POST /api/v1/jobs/createTask with model and input.
Poll GET /api/v1/jobs/recordInfo?taskId=… every 3–5 s (or a callback).

Successful createTask (HTTP 200)

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "task_...",
    "task_id": "task_...",
    "status": "submitted"
  }
}

Completed task (recordInfo)

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "task_...",
    "task_id": "task_...",
    "state": "success",
    "status": "completed",
    "costUsd": "0.384",
    "refunded": false,
    "resultJson": {
      "videos": [
        {
          "url": "https://…/out.mp4"
        }
      ],
      "duration": 8
    }
  }
}

Aliases: task_id = taskId; status: pending / processing / completed / failed alongside state. Clip URL is in resultJson. size is an alias of aspect_ratio in input.

Photos can be any public https links or uploads via files/upload. Videos and audio — via files/upload only.

Error handling

API responses are JSON {"code", "msg", "data"}; errors also have a string error field (type). On /api/v1/* the HTTP status matches body code.

Example response bodies

400

{
  "code": 400,
  "msg": "input.duration: must be between 4 and 30, or \"auto\" / -1",
  "data": null,
  "error": "invalid_request_error"
}

401

{
  "code": 401,
  "msg": "Authentication failed. Please check your API key",
  "data": null,
  "error": "authentication_error"
}

402

{
  "code": 402,
  "msg": "Insufficient balance. Please top up and try again. Available: $0.01, required: $0.015. Top up at https://mixmedia.tech/cabinet/billing",
  "data": {
    "balance": "0.0100",
    "required": "0.0150",
    "currency": "USD",
    "topUpUrl": "https://mixmedia.tech/cabinet/billing"
  },
  "error": "payment_required"
}

429

{
  "code": 429,
  "msg": "Rate limit exceeded: 10 createTask/upload requests per 10 s per key. Retry after 8s",
  "data": null,
  "error": "rate_limit_error"
}

500

{
  "code": 500,
  "msg": "Internal server error",
  "data": null,
  "error": "server_error"
}

Codes on createTask / upload

code	error	Meaning	What to do
400	`invalid_request_error`	Invalid parameter or body	See `msg`
400	`unsupported_model`	Unknown model	Model list
400	`nsfw_content_detected`	Moderation / content policy — `msg` / `failMsg` is the upstream text verbatim	Read the refusal text, change the prompt or files
401	`authentication_error`	Missing or invalid key	Check the key
402	`payment_required`	Not enough balance	Top up
403	`permission_error`	No access	Contact support
429	`rate_limit_error`	Too many requests	Wait for `Retry-After`
505	`model_disabled`	Model temporarily disabled	Pick another
500	`server_error`	Our failure	Retry later

Example msg values: Authentication failed. Please check your API key (401); Insufficient balance. Please top up and try again… (402).

Task errors (recordInfo)

If the task was created and then failed: state: "fail" (alias status: "failed"), failCode / failMsg, and error: { code, message, type }. Money is refunded (refunded: true).

failCode	error.type	Meaning
400	`nsfw_content_detected` / `invalid_request_error`	Moderation — `failMsg` is upstream text verbatim
422	`invalid_request_error`	The model rejected the parameters (length, mode, resolution, file)
501	`server_error`	The model could not generate (`failMsg`)
504	`timeout_error`	Timed out — retry
500 / 503	`server_error`	Service temporarily unavailable

Rate limits

What	Limit
createTask and upload	20 per 10 s per key
recordInfo / list / balance	100 per 10 s per key

Over the limit — HTTP 429 and Retry-After.

#Price

#Media limits

#Parameters (field input)

#Examples

#Prompt only

#With a first frame

#With references

#With your video

#Trim your video

#Create and result

#Successful createTask (HTTP 200)

#Completed task (recordInfo)

#Error handling

#Example response bodies

#Codes on createTask / upload

#Task errors (recordInfo)

#Rate limits