Generate videos using ByteDance SeeDance 1.0 Fast with text-to-video, first & last frame, and multi-frame modes. Supports 5 and 10 second durations at 720p or 1080p.

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Model

bytedance/seedance-1.0-fast

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Supported Modes

ModeDescription
(omit)Text-to-video. You control the aspect ratio.
first_last_frameStart frame required, end frame optional. Aspect ratio auto-detected from input.
multi_frameKeyframe images with per-frame prompts and durations.

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Parameters

ParameterTypeRequiredDefaultDescription
promptstringNo""Text description of the desired video
modestringNonullfirst_last_frame or multi_frame. Omit for text-to-video.
aspect_ratiostringNo"1:1"21:9, 16:9, 4:3, 1:1, 3:4, 9:16. Only used for text-to-video.
durationintegerNo5Duration in seconds: 5 or 10. Auto-calculated in multi_frame mode.
resolutionstringNo"720p"720p or 1080p
seedintegerNorandomSeed for reproducibility
first_frame_urlstringConditionalnullStart frame image. Required for first_last_frame.
last_frame_urlstringNonullEnd frame image. Optional for first_last_frame.
framesobject[]ConditionalnullKeyframes. Required for multi_frame. Min 1.

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Multi-Frame frames Object

FieldTypeRequiredDefaultDescription
image_urlstringNonullKeyframe image URL. Omit for text-only frame.
promptstringNo""Per-frame prompt
durationintegerNo5Segment duration in seconds
At least one frame must have an image_url. Total video duration = sum of all frame durations.

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Example - Text-to-Video

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "bytedance/seedance-1.0-fast",
    "input": {
      "prompt": "A person breakdancing in an urban setting",
      "aspect_ratio": "9:16",
      "duration": 10,
      "resolution": "1080p"
    }
  }'

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Example - First & Last Frame

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "bytedance/seedance-1.0-fast",
    "input": {
      "prompt": "Smooth transition from standing to sitting",
      "mode": "first_last_frame",
      "duration": 5,
      "resolution": "720p",
      "first_frame_url": "https://example.com/standing.jpg",
      "last_frame_url": "https://example.com/sitting.jpg"
    }
  }'

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Example - Multi-Frame

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "bytedance/seedance-1.0-fast",
    "input": {
      "mode": "multi_frame",
      "resolution": "720p",
      "frames": [
        {
          "prompt": "A car driving through a city transitioning from day to night",
          "duration": 3
        },
        {
          "image_url": "https://example.com/daytime.jpg",
          "prompt": "Bright sunny street with the car approaching",
          "duration": 5
        },
        {
          "image_url": "https://example.com/nighttime.jpg",
          "prompt": "Neon-lit street at night as the car drives away",
          "duration": 5
        }
      ]
    }
  }'

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Response

{
  "code": 200,
  "success": true,
  "data": {
    "task_id": "abc123def456",
    "status": "pending"
  }
}