+ printf(
+ "%s takes raw (wav) audio stream and computes power (or magnitude)\n"
+ "of desired frequencies using Goertzel algorithm for time frames\n"
+ "of fixed length (specified in samples or relative to sample rate).\n"
+ "This can be used in various frequency detection applications\n"
+ "like guitar tuning, DTMF decoding and many others...\n"
+ "\n"
+ "http://en.wikipedia.org/wiki/Goertzel_algorithm\n"
+ "\n"
+ "Curently only raw unsigned 8bit (u8) mono audio is supported, but\n"
+ "samplerate may vary. You can convert other formats before processing.\n"
+ "\n"
+ "On lower samplerates and frame sizes this may perform sub-optimally. Eg.:\n"
+ "When set to detect 440Hz (at 8000Hz samplerate and ~4000 samples)\n"
+ "it actually detects something around 438,3Hz rather than 400Hz...\n"
+ "If you can't increase samplerate way around this is just to increase sensitivity.\n"
+ "\n"
+ ,argv[0]
+ );