Function gstreamer_rtsp_server_sys::gst_rtsp_stream_get_rates

pub unsafe extern "C" fn gst_rtsp_stream_get_rates(
    stream: *mut GstRTSPStream, 
    rate: *mut c_double, 
    applied_rate: *mut c_double
) -> gboolean

This is supported on crate feature v1_18 only.