How to check if RasterCodecs engine has started.

Is there any way to check explicitly if the RasterCodecs engine is started?

Also, where is the best place to call the Startup and Shutdown methods? I have seen examples where they are called before and after the use of the codecs, and also examples where Startup is called at the start of the application.

Startup and Shutdown should always be called in pairs.
If you are going to use one global RasterCodecs object repeatedly in your code, call Startup at the beginning and keep it until the very end. This way, you won't have to worry about accidentally calling Startup twice or using the object before it was started.

There is no code to check if Startup was called because it should be easy to track in your code. If you must check, call Startup and handle the exception that gets triggered if it's already started.