Is MediaInfo.Builder's contentId always a URL?

Question

In the Chromecast Android docs, the argument to MediaInfo.Builder is called contentId. In every example I've seen, contentId is passed a URL. Must contentId be a URL, or are there other ways to address content?

Answer 1

It should be the URL of the stream; note that the media needs to reside on some web server so there is no other generic way of addressing that for a cast device.