> The linked tar-ball includes jcapture-0.0.1.cpp that does not save any .wav file. Oh my God! I confused jcapture-0.0.1.cpp (the first attempt) and jcapture-1.0.0.cpp. I will upload the good one during this week-end. > I presume by "frequency shifting & frequency sweeping" you mean resampling the signal & playing it back, not true "pitch shift" with time remaining constant..? Yes, that is, just resampling. Shifting the frequency by 2 means taking a sample of two, and the playback time is divided by two. Thanks for the feedback. I will look at comments and links. Joan Quintana