sol: lab4/volume

lab4/volume/README.md

@@ -0,0 +1 @@
+https://cs50.harvard.edu/x/2023/labs/4/volume/

lab4/volume/volume.c

@@ -0,0 +1,57 @@
+// Modifies the volume of an audio file
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// Number of bytes in .wav header
+const int HEADER_SIZE = 44;
+
+int main(int argc, char *argv[])
+{
+    // Check command-line arguments
+    if (argc != 4)
+    {
+        printf("Usage: ./volume input.wav output.wav factor\n");
+        return 1;
+    }
+
+    // Open files and determine scaling factor
+    FILE *input = fopen(argv[1], "r");
+    if (input == NULL)
+    {
+        printf("Could not open file.\n");
+        return 1;
+    }
+
+    FILE *output = fopen(argv[2], "w");
+    if (output == NULL)
+    {
+        printf("Could not open file.\n");
+        return 1;
+    }
+
+    float factor = atof(argv[3]);
+
+    uint8_t header[HEADER_SIZE];
+    size_t read_bytes = fread(header, 1, HEADER_SIZE, input);
+    size_t written_bytes = fwrite(header, 1, read_bytes, output);
+
+    if (written_bytes != read_bytes)
+    {
+        printf("Error writing to file\n");
+        return 1;
+    }
+
+    int16_t sample;
+    while (fread(&sample, sizeof(int16_t), 1, input))
+    {
+        // ASSUMPTION: does not go beyond UINT16_MAX
+        sample *= factor;
+        fwrite(&sample, sizeof(int16_t), 1, output);
+    }
+
+    // Close files
+    fclose(input);
+    fclose(output);
+}