Tune Musical Instruments.
Guitartune does a Fast Fourier Transform followed by a Harmonic Product Spectrum to calculate the fundamental frequency of sampled audio data.
The sampling and processing is done in a separate thread. The GUI shows the detected note, the required freq, the detected freq, a graphical indication of whether the detected freq is above or below the required one and a Tune Up / Down message.
Guitartune requires gtk+, libglade and libfftw3 (for transforming time domain data to frequency domain). libfftw3 can be obtained from http://www.angstrom-distribution.org/feeds/2007/ipk/glibc/armv4t/base/libfftw3-3_3.1.2-r1_armv4t.ipk