QPitch Documentation

About QPitch 1.0.1

QPitch is a program to tune a musical instrument using your computer and its microphone or line-in input. It's accurate and easy to use. It is designed to be completely cross-platform and works on Linux, Mac and Windows platforms.

The pitch detection algorithm is based on finding the first peak in the autocorrelation of the input signal, which is computed as the inverse Fourier transform of the power spectral density. The pitch detection method is quite reliable (even if a peak may also occur at sub-harmonics or harmonics leading to an erroneous pitch detection).

The estimated pitch is displayed on a note scale graphic, while the input signal and the autocorrelation function may be displayed using an oscilloscope-like plot. The note will be found automatically, since the program doesn't require to select the note to tune manually.

QPitch is an offspring of K3Guitune. The layout of the GUI is quite similar to the original ones, however the application has been rewritten almost from scratch to take advantage of the new features of Qt4 and to use the cross-platform PortAudio library. The FFT is performed using the FFTW library.

The documentation (and even this site) is generated with Doxygen.

Compilation from source

The compilation of QPitch from source requires the following libraries and tools

• Qt4 (version >= 4.2.0)
• PortAudio (version >= pa_stable_v19_061121)
• FFTW (version >= 3.1.0)
• CMake (version >= 2.4.5)

$ tar -xzvf qpitch-1.*.tar.gz
$ cd qpitch-1.*
$ mkdir build
$ cd build
$ cmake ..
$ make