Generate videos with subtitles API

{
    "timeline": {
        "background": "#000000",
        "tracks": [
            {
                "clips": [
                    {
                        "asset": {
                            "type": "title",
                            "text": "Hi, I'm Jeff the founder of Shotstack, the cloud video editing API.",
                            "style": "subtitle",
                            "color": "#ffffff",
                            "size": "small",
                            "background": "#000000",
                            "position": "bottom",
                            "offset": {
                                "y": -0.4
                            }
                        },
                        "start": 1.3,
                        "length": 3.67
                    },
                    {
                        "asset": {
                            "type": "title",
                            "text": "This is a quick demo video to show you just how easy",
                            "style": "subtitle",
                            "color": "#ffffff",
                            "size": "small",
                            "background": "#000000",
                            "position": "bottom",
                            "offset": {
                                "y": -0.4
                            }
                        },
                        "start": 5.07,
                        "length": 3.92
                    },
                    {
                        "asset": {
                            "type": "title",
                            "text": "and quick and simple it is to add captions onto your videos.",
                            "style": "subtitle",
                            "color": "#ffffff",
                            "size": "small",
                            "background": "#000000",
                            "position": "bottom",
                            "offset": {
                                "y": -0.4
                            }
                        },
                        "start": 9.09,
                        "length": 4
                    },
                    {
                        "asset": {
                            "type": "title",
                            "text": "So follow along with the example using Node, PHP or Ruby and within no time",
                            "style": "subtitle",
                            "color": "#ffffff",
                            "size": "small",
                            "background": "#000000",
                            "position": "bottom",
                            "offset": {
                                "y": -0.4
                            }
                        },
                        "start": 13.199,
                        "length": 5.4
                    },
                    {
                        "asset": {
                            "type": "title",
                            "text": "you should be adding captions to your own videos.",
                            "style": "subtitle",
                            "color": "#ffffff",
                            "size": "small",
                            "background": "#000000",
                            "position": "bottom",
                            "offset": {
                                "y": -0.4
                            }
                        },
                        "start": 18.699,
                        "length": 2.36
                    }
                ]
            },
            {
                "clips": [
                    {
                        "asset": {
                            "type": "video",
                            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/examples/captions-example.mp4",
                            "volume": 1
                        },
                        "start": 0,
                        "length": 21.08
                    }
                ]
            }
        ]
    },
    "output": {
        "format": "mp4",
        "resolution": "sd"
    }
}