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I am trying to generate a sine wave of 440Hz frequency that lasts for 10 seconds using the following C code:

#include <stdio.h> #include <math.h> double sine(double amp, double freq, double time); int main(int argc, char *argv[]) { int sample_rate = 48000; double freq = 440; double amp = 1; double duration = 10; double time = 0; double val = 0; int temp = 0; int i = 0; FILE *fp = fopen("sine.bin", "wb"); if (fp == NULL) { return -1; } while (i <= sample_rate * duration) { val = 32767.0 * sine(amp, freq, time); temp = (int) val; fwrite((const void*) &temp, sizeof(int), 1, fp); time = i / (1.0 * sample_rate); i++; } } double sine(double amp, double freq, double time) { return amp * sin(2.0 * M_PI * freq * time); }

However, I am getting a sine wave of 220Hz that lasts for 20 seconds instead. How can I modify this code to produce a sine wave of 440Hz that lasts for 10 seconds? I have compiled and run this code using:

gcc sound.c -Wall -Wextra -lm -o sound && ./sound aplay -r 48000 -f S16_LE sine.bin
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    $\begingroup$ Are you fclose()ing your file? $\endgroup$ Commented Jun 18, 2023 at 0:40
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    $\begingroup$ Also, do you know how many bits are in your int? It might be that int is 32-bits but you're telling your aplay utility that they are 16-bit iintegers. $\endgroup$ Commented Jun 18, 2023 at 0:42
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    $\begingroup$ No, I'm not closing my file, thanks for pointing that mistake out, as it turns out I was mistaken about the number of bits and changing the int for a short fixes it. Thanks! $\endgroup$ Commented Jun 18, 2023 at 1:17

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When trying to generate a 16 bit sound file, using intmeans it is 32 or 64 bit, soshort` must be used when working with a 16 bit audio

C Programming/limits.h

#include <stdio.h> #include <math.h> double sine(double amp, double freq, double time); int main(int argc, char *argv[]) { int sample_rate = 48000; double freq = 220; double amp = 1; double duration = 10; double time = 0; double val = 0; short temp = 0; int i = 0; FILE *fp = fopen("sine.bin", "wb"); if (fp == NULL) { return -1; } while (i <= sample_rate*duration) { val = 32767.0*sine(amp, freq, time); temp = (short) val; fwrite((const void*) &temp,sizeof(short),1,fp); time = i/(1.0*sample_rate); i++; } } double sine(double amp, double freq, double time) { return amp*sin(2.0*M_PI*freq*time); }
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    $\begingroup$ You should fclose() the file. And you should be more careful and explicit in mixing floating-point and integer types together, $\endgroup$ Commented Jun 18, 2023 at 1:54

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