POST a JSON to and API

Hello Folks,

I'm trying to POST a JSON object to an API:

{
  "input": "http://www.example.com/input/video.mov",
  "output": [
    {
      "base_url": "http://www.example.com/output/",
      "filename": "video.mp4",
      "thumbnails": {
        "number": 1,
        "size": "86x66"
      }
    }
  ]
}

What's the best way to post this JSON to an API, e.g. http://www.example.com/api?
How should I create a function that will take an input file name
(video.mov) and output a JSON object as well as POST it to an API?

Thanks!