Function avfilter_graph_send_command 

pub unsafe extern "C" fn avfilter_graph_send_command(
    graph: *mut AVFilterGraph,
    target: *const c_char,
    cmd: *const c_char,
    arg: *const c_char,
    res: *mut c_char,
    res_len: c_int,
    flags: c_int,
) -> c_int