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mplayer is a GPL v2 license.
There is a program called a.out that calls mplayer.
The a.out source code is shown below.
#include <stdio.h>
void main(void){
system("mplayer test.mp4");
}
In this case, a.out uses mplayer.
Do I need to provide a.out source code in accordance with GPL v2?
I understand that a.out does not follow the GPL when running as a command line.
I know that you do not have to provide a.out source code.
Am I correct understanding?
Using system is spawning mplayer in a new process. The GPL and its FAQ are rather clear on this topic e.g. "mere aggregation":
[...] By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs. So when they are used for communication, the modules normally are separate programs. [...]
Here you use "command line arguments" to launch mplayer so I would say that mplayer and your own program are separate. And separate programs means that they can have different licenses.
This not different from launching a tool from a shell or a file manager: the tool license does not impact the licensing of the shell or file manager used to launch the tool.
Therefore:
Do I need to provide a.out source code in accordance with GPL v2?
No.
I know that you do not have to provide a.out source code. Am I correct understanding?
Yes.
And if you redistribute mplayer itself, side-by-side with your code, then of course the GPL still applies to mplayer's code.
