Beeper (libao)

beep.cpp

// g++ -lao -o beep beep.cpp

#include <ao/ao.h>
#include <cmath>
#include <cstdlib>

#define BITS       16
#define CHANNELS   1
#define RATE       22050

class Beeper {
    ao_device *device;
    int driver;
    ao_sample_format format;

    public:
    Beeper() {
        ao_initialize();
        this->driver = ao_default_driver_id();
        
        this->format.bits = BITS;
        this->format.channels = CHANNELS;
        this->format.rate = RATE;
        this->format.byte_format = AO_FMT_LITTLE;
        
        this->device = ao_open_live(driver, &format, NULL);
        if (this->device == NULL)
            exit(1);
    }

    void operator() (double freq, double time, double volume = 0.75) {
        int buf_size = static_cast<int>(this->format.bits/8 * this->format.channels * this->format.rate * time);
        char *buffer = new char[buf_size];
        int sample;
        
        for (int i = 0; i < this->format.rate * time; i++) {
            for (int c = 0; c < this->format.channels; c++) {
                sample = (int)(volume * (1<<(this->format.bits - 1)) * sin(2 * M_PI * freq * ((float) i/format.rate)));
                for (int j = 0; j < this->format.bits/8; j++) {
                    buffer[this->format.bits/8*i*this->format.channels + this->format.channels*c + j] = sample & 0xff;
                    sample >>= 8;
                }
            }
        }
        ao_play(device, buffer, buf_size);
        delete[] buffer;
    }

    ~Beeper() {
        ao_close(device);
        ao_shutdown();
    }
};

int main(int argc, char **argv)
{
    Beeper b;
    
    int count = (argc == 1) ? 20 : atoi(argv[1]);
    
    for (int i=0; i < count; i++){
        b(880.0, 0.3);
        b(0.0, 0.2);
    }

    return 0;
}