How do I change the background of a video?

I want to change the background of a video. Is this possible?

There are two ways to change the background of a video:

  1. Default background colour of the viewport
  2. Specific background colour at specific timestamp

Default background colour of the viewport

{
    "timeline": {
        "soundtrack": {
            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/music/freepd/advertising.mp3"
        },
        "background": "#45dae8",
        "tracks": [
            {
                "clips": [
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p>HELLO CYAN</p>",
                            "css": "p { font-family: \"Montserrat ExtraBold\"; color: #ffffff; font-size: 64px; text-align: center; }",
                            "width": 1280,
                            "height": 720,
                            "background": "transparent"
                        },
                        "start": 1,
                        "length": 5,
                        "transition": {
                            "in": "fade",
                            "out": "fade"
                        }
                    }
                ]
            }
        ]
    },
    "output": {
        "format": "mp4",
        "resolution": "hd"
    }
}

Specific background colour at specific timestamp

Template link

{
    "timeline": {
        "soundtrack": {
            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/music/freepd/advertising.mp3"
        },
        "background": "#FFFFFF",
        "tracks": [
            {
                "clips": [
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p>HELLO CYAN</p>",
                            "css": "p { font-family: \"Montserrat ExtraBold\"; color: #ffffff; font-size: 64px; text-align: center; }",
                            "width": 1280,
                            "height": 720,
                            "background": "transparent"
                        },
                        "start": 1,
                        "length": 5,
                        "transition": {
                            "in": "fade",
                            "out": "fade"
                        }
                    },
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p></p>",
                            "width": 1280,
                            "height": 720,
                            "background": "#45dae8"
                        },
                        "start": 0,
                        "length": 7
                    },
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p>HELLO PINK</p>",
                            "css": "p { font-family: \"Montserrat ExtraBold\"; color: #ffffff; font-size: 64px; text-align: center; }",
                            "width": 1280,
                            "height": 720,
                            "background": "transparent"
                        },
                        "start": 8,
                        "length": 5,
                        "transition": {
                            "in": "fade",
                            "out": "fade"
                        }
                    },
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p></p>",
                            "width": 1280,
                            "height": 720,
                            "background": "#da8afc"
                        },
                        "start": 7,
                        "length": 7
                    }
                ]
            }
        ]
    },
    "output": {
        "format": "mp4",
        "resolution": "hd"
    }
}