custom_watermark_filename=https://server/pics/watermark.pngPOST /rest-api/transcoder2/startup HTTP/1.1
Host: localhost:8081
Content-Type: application/json
{
    "uri": "transcoder2://tcode2",
    "remoteStreamName": "test",
    "localStreamName": "testT",
    "encoder": {
        "width": 320,
        "height": 240,
        "keyFrameInterval": 60,
        "fps": 30,
        "watermark": "https://server/pics/watermark.png"
    }
}