Allow to create empty arguments

[CriggerMarg]

I was in need to create command like
-loop 1 -i "empty.png" -t 31
and was unable to do so because I have to use some input first.
So I was getting
-i "empty.png" -loop 1 -t 31
instead and that is wrong command, it does not produce video with desired length.

Now I can use it like this

FFMpegArguments.FromEmpty(options => options.Loop(1))
.AddFileInput("empty.png")
...

[rosenbjerg]

Can't the same thing be achieved with FFMpegArguments.FromFileInput("/path", opt => opt.Loop(1)).OutputTo....?

[rosenbjerg]

Options on Input are put before -i ..., similarly, options to output are put before the output arg

[CriggerMarg]

Options on Input are put before -i ..., similarly, options to output are put before the output arg

Well, yes. That way works. My apologies, closing PR