A command line taptempo written in modern Fortran and under GNU GPLv3 license. Listen to a song and hit enter key with style and you'll get the corresponding number of beats per minute (BPM). This tool is very useful to quickly find the tempo of a song. You can also use it to measure your heart rate: (gently) put one hand around your throat and tap the enter key at each beat.

The original TapTempo was written in C++, but lots of porting in other languages have been developed via the LinuxFr website. There is even a TapTempo Federation.

You need a modern Fortran compiler.

You can easily build and run the project using the Fortran Package Manager fpm (https://github.com/fortran-lang/fpm) at the root of the project directory:

$ fpm build
$ fpm run
 Hit Enter key for each beat (q to quit).

 [Hit enter key one more time to start BPM computation...]

Tempo:      85. BPM

Tempo:      83. BPM

Tempo:      84. BPM

Tempo:      84. BPM

Tempo:      81. BPM

To add options, put them after --:

$ fpm run -- -r 3 -s 8 -p 2

Or you can also use the build.sh script if you don't have fpm installed, or just simply type:

$ gfortran -o taptempo src/taptempo.f90 app/main.f90
* ./taptempo

Usage : taptempo [options]

Options :
  -h, --help            display this help message
  -p, --precision       change the number of decimal for the tempo,
                        the default is 0 decimal places, the max is 5 decimals
  -r, --reset-time      change the time in seconds to reset the calculation,
                        the default is 5 seconds
  -s, --sample-size     change the number of samples needed to calculate the tempo,
                        the default is 5 samples, the minimum is 2
  -v, --version         print the version number

• Post a message in the GitHub Issues tab to discuss the function you want to work on.
• Concerning coding conventions, follow the stdlib conventions: https://github.com/fortran-lang/stdlib/blob/master/STYLE_GUIDE.md
• When ready, make a Pull Request.

• https://en.wikipedia.org/wiki/Tempo

• Introduced by Fortran 90:

  • SYSTEM_CLOCK()
    • My first idea was to use cpu_time() but I soon realised that the process was idle while the read(*, '(a1)') key was waiting for an input! That’s why I finally used system_clock().
    • A 64 bits integer can go up to 2**63-1 = +9223372036854775807. Even if the clock resolution is nanosecond, we could count 9223372036 seconds ~ 106751 days ~ 292 years.

• Introduced by Fortran 2003:

  • COMMAND_ARGUMENT_COUNT()
  • GET_COMMAND_ARGUMENT()

• Introduced by Fortran 2008:

  • ISO_FORTRAN_ENV real64 and int64