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Piano from Terminal

I'm learning to play Piano but my terminal call me.. What about a simple piano visualizer in the terminal?

I need a simple visualizer that highlights piano keys.. I don't need it, really, but its fun to make everythings in the terminal (or not?). This visualizer looks like this:

Piano Screenshot


I have tried to write this tool with a "simple" bash script but i know C and i am more "productive" with C. So this is the main structure of the program:

    where p[0] is the top line of the piano
          p[1] is the middle line of the piano
          p[2] is the bottom line of the piano
    foreach p[COLUMN] there are 14 keys for each OCTAVE
        [0] is the C key
        [1] is the C# key
        [2] is the D key
        [3] is the D# key
        [4] is the E key
        [5] is a dummy key for a not existent semitone
        [6] is the F key
        [12] is the A# key
        [13] is a dummy key for a not existent semitone 
char p[3][14*N_OCT]={0};

int main(int argc, char *argv[]) {
    //check argv for arguments

    //for each note in arguments hightlight p[0..2][NOTE]

    //draw all piano keys

The trick of using 14 keys instead of the standard 12 is used to calculate a key index, trought octaves, in a simpler way, assuming that each tone has a semitone. This is not true for E-F and B-C intervals but the program will intercept this exceptions and skip the [5] and the [13] dummy keys (not existent semitones).

This is how this trick work:

1) Notes are translated to numbers:

NOTE_INDEX: C=0 D=2 E=4 F=6 G=8 A=10 B=12

2) This formula is used to find the index of a key for a note without alterations:


3) (optional) code to add a semitone to a KEY_INDEX:


4) (optional) code to add two semitones (##):

two time the first algorithm

5) (optional) code to subtract a semitone (b):

one time the first algorithm with -1 instead of +1

6) (optional) code to subtract two semitones (bb):

two time the subtract of a single semitone

By using The trick of 14 keys, instead of 12, the program is pretty simple. For each note (ex: A2#) passed as an argument, the program will highlight the key using Terminal colors. After highlights of all keys the program draw all 12 keys (skipping the 5 and the 13 dummy keys).


The full source of this program is here. The program use ANSI ESCAPE CODE to colorize the terminal output, so will run fine on a Linux machine, on Mac OS X or with MinGW on Windows.


To compile this program you do not need any fancy arguments:

gcc piano.c -o piano


This program accept a list of notes where each note syntax is


For example if you want to highlight a C# you write C# (or B), if you want a C# on the second octave you write C2# (or B2), if you want a C with two semitones alteration you write C## (or B#).

By default the program will display 3 octaves but you can change that by using the -o (or --octaves) parameters.

The maximum number of octaves supported by the program is 10. You can extend this values by modifing the sourcecode, changing the value of the N_OCT macro.

Ok, this tool is useless... but exists :-D