generating audio in C

This is a discussion on generating audio in C within the C Programming forums, part of the General Programming Boards category; Hi, Iam trying to design a small C programme which can generate a squarewave function and play a sequence of ...

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    generating audio in C

    Hi,

    Iam trying to design a small C programme which can generate a squarewave function and play a sequence of musical notes for 30 seconds. How would i go about doing this?

    Many Thanks

    teknologik

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    Under some compilers, there is a function called sound(). Note that this function is not portable, so don't rely on it. For audio, I would suggest a library such as SDL and/or SDL_Mixer.

    EDIT: The compiler I discovered the sound() function on is called DJGPP.
    Last edited by kawk; 05-09-2007 at 03:42 PM.

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    i know how to make the square wave using C its just im not sure how to generate a sequence of musical notes correctly.

    static char seq[]="CDEFGABAGFEDC"; but thats as far as i can get

    does anyone know how to generate a sequence of notes?

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    Well, presuming this is homework, I'd suggest looking into whatever your professor or tutor suggests . . .

    IF (and only if) your tutor/professor can't tell you what to use, try sound() and a lookup table of freqs.

    EDIT: If this isn't homework, I'm sorry . . .

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    my school days have been and gone; so lucky for me this isnt homework other wise i would never get it handed in on time lol just trying to learn some C thats all, how would i go about making a look up table then

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    Well, I know that middle A is 440 . . . I have a lookup table around here somewhere . . .

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    Here you go:
    Code:
    #define _LC 130
    #define _LCS 137
    #define _LD 145
    #define _LDS 155
    #define _LE 166
    #define _LF 175
    #define _LFS 185
    #define _LG 195
    #define _LGS 207
    #define _LA 220
    #define _LAS 235
    #define _LB 245
    
    #define _MC 260
    #define _MCS 275
    #define _MD 290
    #define _MDS 311
    #define _ME 333
    #define _MF 350
    #define _MFS 370
    #define _MG 390
    #define _MGS 415
    #define _MA 440
    #define _MAS 470
    #define _MB 490
    
    #define _HC 520
    So, _LC is Low C, i.e. one octave below Middle C. _LCS is one semitone higher.

    BTW, I found this by playing them on my piano (which was out of tune at the time . . .) so they may be a little off. You do know that one octave higher is double the freq, right?

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    Googling for "piano note hertz" turned up this page: http://www.vibrationdata.com/piano.htm
    It has hertz values for different notes.

    [edit] Also, see this Wikipedia entry: http://en.wikipedia.org/wiki/Note
    Scroll down to Note frequency (hertz) for a formula for calculating frequency values. [/edit]
    dwk

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    So, a simple program to play the above sequence you mentioned:

    Code:
    #include <stdio.h>
    #include <unistd.h>
    
    int main() {
        int notes[14] = {_MC, _MD, _M, _ME, _MF, _MG, _LA, _LB, _LA, _LG, _LF, _LE, _LD, _LC};
        int x;
        for(x = 0; x < 14; x ++) {
            sound(notes[x]);
            delay(100); /* NOTE! THIS CRASHES WINDOWS 98 SOMETIMES */
        }
        sound(0);
        return 0;
    }
    Two things: I apoligize about the underscore leading the #defines, and this code _may_ not work, as I haven't compiled it yet . . .

    EDIT: Try sleep(), but I don't know if RHIDE/DJGPP supports it . . .

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    Frequently Quite Prolix dwks's Avatar
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    DJGPP's sound() function appears to be in pc.h: www.delorie.com/djgpp/doc/libc/libc_735.html

    That function looks very unportable. Perhaps there is a Windows function that would be more likely to work with the OP's existing compiler?
    dwk

    Seek and ye shall find. quaere et invenies.

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    I don't know, as I am suggesting a possible solution, not a rock-solid answer. Oops :P.
    Last edited by kawk; 05-09-2007 at 04:25 PM. Reason: Speling eror

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    Quote Originally Posted by kawk View Post
    So, a simple program to play the above sequence you mentioned:

    Code:
    #include <stdio.h>
    #include <unistd.h>
    
    int main() {
        int notes[14] = {_MC, _MD, _M, _ME, _MF, _MG, _LA, _LB, _LA, _LG, _LF, _LE, _LD, _LC};
        int x;
        for(x = 0; x < 14; x ++) {
            sound(notes[x]);
            delay(100); /* NOTE! THIS CRASHES WINDOWS 98 SOMETIMES */
        }
        sound(0);
        return 0;
    }
    Two things: I apoligize about the underscore leading the #defines, and this code _may_ not work, as I haven't compiled it yet . . .

    EDIT: Try sleep(), but I don't know if RHIDE/DJGPP supports it . . .
    hello kwak,

    the compiler which i am using Turbo C v 2.0.1 (i think) didnt seem to like the _ between the notes, is there anything you can suggest which may work?

    thanks

  13. #13
    and the hat of wrongness Salem's Avatar
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    > the compiler which i am using Turbo C v 2.0.1
    Lemme guess, your OS is XP ?

    Would you buy a Ferrari, and replace the engine with a steam engine?
    Because that is what you've done by trying to use TC2.01 on a modern machine.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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    yes the os is xp

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    ok then salem what do you recommend a suitable compiler?

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