design: update tracer design
design: update tracer design

jpxiong/gstreamer,jpxiong/gstreamer,centricular/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,centricular/gstreamer,centricular/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,centricular/gstreamer,StreamUtils/gstreamer