Summary
FMIT is a graphical utility for tuning your musical instruments, with error and volume history and advanced features.Features
- Estimation of the fundamental frequency (f0) of an audio signal, in real-time.
(the f0, not the perceived pitch) - Harmonics' amplitude
- Waveform's period
- Discrete Fourier Transform (DFT)
- Microtonal tuning (supports scala file format)
- Statistics
- All views are optional so that the interface can be as simple as possible.
(make it easy to see on a distant screen) - Can support OSS, ALSA, PortAudio and Jack sound systems.
- Everything runs under Linux
, Mac OSX 
and Windows 
(100% FREE award granted by Softpedia)
Technicalities
Last 
on Linux, macOS, and Windows
It is coded in C/C++ using the Qt library 
and stored on GitHub 
Most of the programming code is under GPL (v2) License
and
Copyright © 2004 Gilles Degottex, and under LGPL (v2) License, otherwise.
See the file README.txt for more details.
Credits
Developing an open-source software would be impossible without external, direct or indirect help. Thus, 1000 Thanks to the following geeks:Florian Hars for the tuning scales; Arnout Engelen for the JACK issues; John Anderson for the microtonal module idea; Scott Bahling for the scales in cents; Jacob Shapiro for his help to make FMIT working under Windows/Cygwin.
Translators: Omega9 (Russian), skarmoutsosv (Greek), Pindaro and dsboger (Portuguese and Brazilian Portuguese), Florian Maier (German).
Packagers: Toni Graffy and all the PackMan team, Ludovic Reslinger, Edward Tomasz Napierala, John Wright, dsboger.
With a special thanks to dsboger for all the little and usefull changes, updates, packaging, etc!
Disclaimer: This software comes with no warranties of any kind and the copyright owner and contributors can be liable for nothing. See the Disclaimer section of README.txt for more details.