I don't understand, do you want to compile your library using FFI or do you want to bind a library compiled your way with FFI ?
If you want to compile your library using FFI, then use OSProcess to run the compilation line you showed.
If you want to bind a library compiled your way with FFI, the easiest way is to compile the C files as a dylib with something like:
gcc -shared -m32 -Wall helloworld.c -o helloworld.dylib $(pkg-config --cflags --libs gstreamer-1.0)
(replace .dylib by .so or .dll if you're on windows or on Mac).
Then you can bind the dynamic library generated with FFI. I am not sure about the FFI syntax but with NativeBoost it would look like:
Integer>>fib4NB
<primitive: #primitiveNativeCall module: #NativeBoostPlugin error: errorCode>
^ self
nbCall: #( int functionToCall (int self) )
module: '/Users/myName/Desktop/helloWorld.dylib'
Regards,
Clement