To see this in action, here's a video: <a href="https://www.youtube.com/watch?v=IqxAVGRPow0" rel="nofollow">https://www.youtube.com/watch?v=IqxAVGRPow0</a><p>I based parts of the app on Ringdroid, using its code to do the waveform display and the selection sliders.