CZML file

I was recently able to run Simple Hello world. My next step is to create / write CZML file.

I have two question

  1. My input file is in JSON can that be converter to .czml format ?

sample [{“time”:0.0,“lat”:34.5764,“lon”:-120.632,“alt”:4.2164,“speed”:383.3641118772521}]

  1. Does cesium support varying speed as in the sample above?