selectionBox Parameter Reference

selectionBox defines an axis-aligned rectangular region within a video frame. It is currently used by the Video Object Remove API (POST /common-task/video-object-remove/submit).

Diagram

The diagram below shows the geometric meaning of each selectionBox field. The origin is at the top-left corner of the video frame. All values are expressed as percentages of the video’s width and height.

Data Structure

{
  "selectionBox": {
    "x": 25.4,
    "y": 48.1,
    "w": 33.2,
    "h": 12.6
  }
}

Field	Type	Required	Valid Range	Description
`x`	number	Yes	`[0, 100]`	Horizontal offset of the top-left corner, as a percentage of video width
`y`	number	Yes	`[0, 100]`	Vertical offset of the top-left corner, as a percentage of video height
`w`	number	Yes	`(0, 100]`	Width of the selection area, as a percentage of video width
`h`	number	Yes	`(0, 100]`	Height of the selection area, as a percentage of video height

Coordinate Rules

Origin: The top-left corner of the video frame is (0, 0). x increases to the right; y increases downward.
Units: All fields are percentages of the video’s native width and height — not pixels, and not normalized 0~1 coordinates.
Must stay inside the frame: x + w ≤ 100 and y + h ≤ 100.
Positive area: w > 0 and h > 0.
Minimum size: After conversion to pixels, both the width and height of the selection area must be at least 4 pixels. For example, on a 720×480 video, w must satisfy w/100 × 720 ≥ 4, i.e. w ≥ 0.56.
Shape: Only axis-aligned rectangles are supported. Rotated rectangles and polygons are not supported.
Precision: Decimal values are supported (two decimal places are recommended, e.g. 25.40).

Usage with `mode`

`mode`	`selectionBox` required?	Behavior
`auto`	No (ignored if provided)	Automatic object removal across the full frame
`clear-inside`	Yes	Remove content inside the selection; keep the area outside unchanged
`clear-outside`	Yes	Keep content inside the selection; clear everything outside the box

Request Example

curl -X POST 'https://api.topview.ai/common-task/video-object-remove/submit' \
  -H 'Authorization: Bearer <your-api-key>' \
  -H 'Topview-Uid: <your-topview-uid>' \
  -H 'Content-Type: application/json' \
  -d '{
    "mode": "clear-inside",
    "videoFileId": "file_abc123",
    "selectionBox": {
      "x": 25.4,
      "y": 48.1,
      "w": 33.2,
      "h": 12.6
    }
  }'

Common Errors

Code	When it occurs
`4008`	Invalid `mode` (not `auto`, `clear-inside`, or `clear-outside`)
`4009`	Invalid `selectionBox`: missing fields, out-of-range values (< 0 or > 100), `w` or `h` ≤ 0, `x + w` or `y + h` > 100, or shortest side < 4 px after pixel conversion
`4010`	Invalid `videoFileId`, or the file is not a supported video format
`4011`	Failed to parse video metadata (width, height, or duration)

FAQ

Q1: Can I pass pixel coordinates?
No. selectionBox only accepts percentage values in the range 0~100. The server converts them to pixels based on the uploaded video’s actual resolution.

Q2: Can I define a rotated or irregular region?
Not in the current version — only axis-aligned rectangles are supported. For full-frame processing without a manual box, use mode: auto.

Q3: Must x + w be strictly ≤ 100?
Yes. Values that extend beyond the frame will return error 4009. Clip or validate the box on the client before submitting.