Seedance 2.5 API

ReachAPI exposes ByteDance Seedance 2.5 through the public model ID seedance-2-5 and the unified asynchronous video task API.

• Create task: POST /v1/vids/create
• Query task: GET /v1/tasks/{task_id}
• Execution: asynchronous; poll the task endpoint or provide callback_url
• Model ID: seedance-2-5

Authentication

Authorization: Bearer YOUR_REACH_API_KEY
Content-Type: application/json

Capabilities and pricing

input.content is required and must be a non-empty array. Legacy fields such as prompt, image_url, and video_urls are not converted automatically.

Billing uses returned output token usage, not video duration. ReachAPI maps BytePlus usage.completion_tokens to usage.output_tokens and settles the successful task from that value.

Create a task

curl -X POST "https://direct.reachapi.ai/v1/vids/create" \
  -H "Authorization: Bearer YOUR_R..._KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedance-2-5",
    "input": {
      "content": [
        {
          "type": "text",
          "text": "A cinematic train journey through a mountain valley at sunrise"
        }
      ],
      "duration_seconds": 12,
      "resolution": "720p",
      "aspect_ratio": "16:9",
      "watermark": false
    }
  }'

{
  "model": "seedance-2-5",
  "callback_url": "https://your-domain.com/callback",
  "input": {
    "content": [
      {
        "type": "text",
        "text": "A cinematic train journey through a mountain valley at sunrise"
      }
    ],
    "duration_seconds": 12,
    "resolution": "720p",
    "aspect_ratio": "16:9",
    "generate_audio": true,
    "watermark": false
  }
}

Top-level parameters

input parameters

Seedance 2.5 does not support seed, edit_mode, or extend_mode. Express editing and continuation with reference content plus a text prompt.

input.content

URLs are nested under image_url.url, video_url.url, or audio_url.url. Every client media URL must be a publicly reachable https:// URL. HTTP, Base64, data: URLs, bare Base64, and client-supplied asset:// values are rejected.

First/last-frame inputs cannot be mixed with reference_image, reference_video, or reference_audio. A last frame requires a first frame, and every first/last-frame request must explicitly set aspect_ratio to adaptive.

Request examples

Audio-only input with MOV output

{
  "model": "seedance-2-5",
  "input": {
    "content": [
      {
        "type": "audio_url",
        "role": "reference_audio",
        "audio_url": { "url": "https://cdn.example.com/music.mp3" }
      }
    ],
    "duration_seconds": 20,
    "resolution": "720p",
    "aspect_ratio": "adaptive",
    "generate_audio": true,
    "output_format": "mov",
    "priority": 5
  }
}

Reference-video editing or continuation

{
  "model": "seedance-2-5",
  "input": {
    "content": [
      {
        "type": "text",
        "text": "Continue this scene into a rainy night and preserve the camera movement"
      },
      {
        "type": "video_url",
        "role": "reference_video",
        "video_url": { "url": "https://cdn.example.com/source.mp4" }
      }
    ],
    "duration_seconds": 10,
    "resolution": "480p",
    "aspect_ratio": "16:9"
  }
}

Do not add edit_mode or extend_mode; the content and prompt define the operation.

Responses, polling, and callbacks

Submission response:

{
  "code": 200,
  "msg": "",
  "status": "queued",
  "task_id": "task_xxx",
  "data": []
}

Poll GET /v1/tasks/task_xxx until status is success or failed.

{
  "code": 200,
  "msg": "",
  "status": "success",
  "task_id": "task_xxx",
  "data": [{ "url": "https://cdn.example.com/generated/video.mov" }],
  "usage": {
    "input_tokens": 0,
    "output_tokens": 102960,
    "total_tokens": 102960
  },
  "cost": { "spend": 1.101672 }
}

Successful video results include data[].url. When callback_url is provided, ReachAPI sends the same terminal response structure to it with POST.

Human-subject media handling

BytePlus may require human or private-portrait reference media to be stored in its Asset Library. If the first submission returns that class of error, ReachAPI uploads the original HTTPS media to the current provider's asset library, rewrites it internally, and retries once. Clients still submit the original HTTPS URLs and must not submit asset:// values.

Constraints and errors

• input.content and resolution are required
• Duration must be 4-30 or -1; 1080p is not supported
• At most 1 text item, 30 images, 10 videos, and 10 audio files
• video_url requires reference_video; audio_url requires reference_audio
• Unknown input fields, unsupported legacy fields, and invalid media URLs return 400
• 401 indicates an invalid API key, 402 insufficient credits, 422 a safety rejection, and 429 rate limiting