unsafe extern "C" fn video_sink_show_frame<T: VideoSinkImpl>(
ptr: *mut GstVideoSink,
buffer: *mut GstBuffer,
) -> GstFlowReturn
unsafe extern "C" fn video_sink_show_frame<T: VideoSinkImpl>(
ptr: *mut GstVideoSink,
buffer: *mut GstBuffer,
) -> GstFlowReturn