gstreamer 环境变量配置

export GST_PLUGIN_SCANNER=`pwd`/../gst/libexec/gstreamer-1.0/gst-plugin-scanner
export GST_PLUGIN_PATH=`pwd`/../gst/lib/gstreamer-1.0/
export GI_TYPELIB_PATH=`pwd`/../gst/lib/girepository-1.0/