ltx/ltx-2/fast/image-to-video

Generate fast, realistic 4K videos from text or images with smooth 50-fps motion, synchronized audio, and efficient performance for cinematic storytelling and creative visualization.

1. Get started

Use RunComfy's API to run ltx/ltx-2/fast/image-to-video. For accepted inputs and outputs, see the model's schema.

curl --request POST \
  --url https://model-api.runcomfy.net/v1/models/ltx/ltx-2/fast/image-to-video \
  --header "Content-Type: application/json" \
  --header "Authorization: Bearer <token>" \
  --data '{
    "image_url": "https://playgrounds-storage-public.runcomfy.net/tools/7233/media-files/input-1-1.jpg",
    "prompt": "A woman stands still amid a busy neon-lit street at night. The camera slowly dollies in toward her face as people blur past, their motion emphasizing her calm presence."
  }'

2. Authentication

Set the YOUR_API_TOKEN environment variable with your API key (manage keys in your Profile) and include it on every request as a Bearer token via the Authorization header: Authorization: Bearer $YOUR_API_TOKEN.

3. API reference

Submit a request

Submit an asynchronous generation job and immediately receive a request_id plus URLs to check status, fetch results, and cancel.

curl --request POST \
  --url https://model-api.runcomfy.net/v1/models/ltx/ltx-2/fast/image-to-video \
  --header "Content-Type: application/json" \
  --header "Authorization: Bearer <token>" \
  --data '{
    "image_url": "https://playgrounds-storage-public.runcomfy.net/tools/7233/media-files/input-1-1.jpg",
    "prompt": "A woman stands still amid a busy neon-lit street at night. The camera slowly dollies in toward her face as people blur past, their motion emphasizing her calm presence."
  }'

Monitor request status

Fetch the current state for a request_id ("in_queue", "in_progress", "completed", or "cancelled").

curl --request GET \
  --url https://model-api.runcomfy.net/v1/requests/{request_id}/status \
  --header "Authorization: Bearer <token>"

Retrieve request results

Retrieve the final outputs and metadata for the given request_id; if the job is not complete, the response returns the current state so you can continue polling.

curl --request GET \
  --url https://model-api.runcomfy.net/v1/requests/{request_id}/result \
  --header "Authorization: Bearer <token>"

Cancel a request

Cancel a queued job by request_id, in-progress jobs cannot be cancelled.

curl --request POST \
  --url https://model-api.runcomfy.net/v1/requests/{request_id}/cancel \
  --header "Authorization: Bearer <token>"

4. File inputs

Hosted file (URL)

Provide a publicly reachable HTTPS URL. Ensure the host allows server‑side fetches (no login/cookies required) and isn't rate‑limited or blocking bots. Recommended limits: images ≤ 50 MB (~4K), videos ≤ 100 MB (~2–5 min @ 720p). Prefer stable or pre‑signed URLs for private assets.

5. Schema

Input schema

{
  "type": "object",
  "title": "Input",
  "required": [
    "image_url",
    "prompt"
  ],
  "properties": {
    "image_url": {
      "title": "Image URL",
      "description": "Supports PNG, JPEG, WebP, AVIF formats.",
      "type": "string",
      "default": "https://playgrounds-storage-public.runcomfy.net/tools/7233/media-files/input-1-1.jpg"
    },
    "prompt": {
      "title": "Prompt",
      "description": "",
      "type": "string",
      "default": "A woman stands still amid a busy neon-lit street at night. The camera slowly dollies in toward her face as people blur past, their motion emphasizing her calm presence."
    },
    "duration": {
      "title": "Duration",
      "description": "The duration of the generated video in seconds. The fast model supports 6–20 seconds. Durations longer than 10 seconds (12, 14, 16, 18, 20) are only supported with 25 FPS and 1080p resolution.",
      "type": "integer",
      "enum": [
        6,
        8,
        10,
        12,
        14,
        16,
        18,
        20
      ],
      "default": 6
    },
    "resolution": {
      "title": "Resolution",
      "description": "The resolution of the generated video. Aspect ratio supported: 16:9 only. Default value: 1080p.",
      "type": "string",
      "enum": [
        "1080p",
        "1440p",
        "2160p"
      ],
      "default": "1080p"
    },
    "aspect_ratio": {
      "title": "Aspect Ratio (W:H)",
      "description": "The aspect ratio of the generated video. Only 16:9 is supported.",
      "type": "string",
      "enum": [
        "16:9"
      ],
      "default": "16:9"
    },
    "fps": {
      "title": "Frames Per Second",
      "description": "Frames per second of the generated video.",
      "type": "integer",
      "enum": [
        25,
        50
      ],
      "default": 25
    },
    "generate_audio": {
      "title": "Generate Audio",
      "description": "Whether to generate audio for the generated video.",
      "type": "boolean",
      "default": true
    }
  }
}

Output schema

{
  "output": {
    "type": "object",
    "properties": {
      "image": {
        "type": "string",
        "format": "uri",
        "description": "single image URL"
      },
      "video": {
        "type": "string",
        "format": "uri",
        "description": "single video URL"
      },
      "images": {
        "type": "array",
        "description": "multiple image URLs",
        "items": { "type": "string", "format": "uri" }
      },
      "videos": {
        "type": "array",
        "description": "multiple video URLs",
        "items": { "type": "string", "format": "uri" }
      }
    }
  }
}