How to create caption with border radius?

Subject: Assistance Needed for Rounded Border Captions Using Shotstack API

Dear Shotstack Support Team,

I am using the Shotstack API to generate video captions and would like to customize them with a rounded border effect (similar to CSS border-radius). However, I have not found a way to achieve this effect through the API.

Could you please guide me on how to apply rounded borders to captions using the Shotstack API? If there are specific parameters or styling options available, I would greatly appreciate your guidance.

Looking forward to your support and any relevant documentation you can provide.

You can use the same styling options as the text asset, which includes border radius:

{
  "timeline": {
    "fonts": [
      {
        "src": "https://fonts.gstatic.com/s/notosanskr/v36/PbyxFmXiEBPT4ITbgNA5Cgms3VYcOA-vvnIzzuoySLPg9A.ttf"
      }
    ],
    "background": "#FFFFFF",
    "tracks": [
      {
        "clips": [
          {
            "length": "end",
            "asset": {
              "type": "caption",
              "src": "https://shotstack-assets.s3.amazonaws.com/captions/transcript.srt",
              "width": 500,
              "font": {
                "family": "Noto Sans KR",
                "size": "50",
                "lineHeight": 1,
                "color": "#000000"
              },
              "alignment": {
                "horizontal": "center"
              },
              "background": {
                "color": "#fedc00",
                "borderRadius": 45,
                "padding": 25
              }
            },
            "offset": {
              "x": 0.1,
              "y": 0.1
            },
            "start": 0,
            "position": "center"
          }
        ]
      },
      {
        "clips": [
          {
            "asset": {
              "type": "video",
              "src": "https://github.com/shotstack/test-media/raw/main/captioning/scott-ko.mp4",
              "volume": 1
            },
            "start": 0,
            "length": "auto"
          }
        ]
      }
    ]
  },
  "output": {
    "format": "mp4",
    "fps": 25,
    "size": {
      "width": 1280,
      "height": 720
    }
  }
}