hello @marsman12019, I've worked on something really similar some months ago http://edapx.com/2015/05/25/facetracker-sketch/
To track the mouth, you can use something like
ofxFaceTracker tracker;
ofPolyline mouthProfile = tracker.getImageFeature(ofxFaceTracker::OUTER_MOUTH);
You can find an implementation in this method ofApp::grabMouth https://github.com/edap/bubbles/blob/master/src/ofApp.cpp#L44
