Register a custom loader callback. For every file that is requested this callback is called with the url and mimetype. It should return a custom loader or null if it does not want to handle the file.
Register a callback to determine the mimetype of a file. This is to support custom loaders. The callback will provide the URL of the file to load + a range request response with the first few bytes of the file. The callback should return a mimetype or null if it does not want to handle the file.
Model loader callbacks for customizing load behavior