sound.c

#include <stdio.h>
#include <math.h>
#include "sound.h"
#include "screen.h"

// this function gets in an array of decibel values and finds out the number
// of peaks in this array
int findPeaks(int d[]) {
        int i, c = 0;
        for(i = 1; i < 80; i++) {
                if(d[i] >= 75 && d[i-1] < 75) c++;
        }
        if(d[0] >= 75) c++;
        return c;
}

// this function takes 1 sec of sample (16000) and caculate
// 80 pieces of RMS value, and then turn these values
// into decibels, and display them as a barchart
void displayWAVDATA(short s[]){
	double rms[80]; // because of 16000 samples, 16000/80=200
	
	int db[80];				// therefore every 200 samples makes one RMS
	int i, j;
	short *ptr = s;		// we use a pointer, pointing to the beginning of array
	
	
	for(i=0; i<80; i++){
		double sum = 0;		// accumulate sum of squares
		for(j=0; j<200; j++){
			sum += (*ptr) * (*ptr);
			ptr++;			// pointing to the next sample
		}
		rms[i] = sqrt(sum/200);
		db[i] = 20*log10(rms[i]);// decibel value
#ifdef DEBUG				// conditional compilation
		printf("rms[%d] = %f\n", i, rms[i]);
#endif
	} // end if for
#ifndef DEBUG
	barChart(db);
	int peaks = findPeaks(db);      // get the number of peaks
        setColors(WHITE, bg(BLACK));    // set the colors
        printf("\033[1;41H");           // go to the row 1, col 41
        printf("Peaks: %d          \n", peaks);
#endif
}

void showID(char *name, char *value){
	printf("%s: ",name);
	for(int i=0; i<4; i++)
		printf("%c", value[i]);
	puts("");
}

//function definition
void displayWAVHDR(struct WAVHDR h){
#ifdef DEBUG
	showID("Chunk ID", h.ChunkID);
	printf("Chunk size: %d\n", h.ChunkSize);
	showID("Format", h.Format);
	showID("Subchunk 1 ID", h.Subchunk1ID);
	printf("Subchunk 1 size: %d\n", h.Subchunk1Size);
	printf("Audio format: %d\n", h.AudioFormat);
	printf("Number of channels: %d\n", h.NumChannels);
	printf("Sample rate: %d\n", h.SampleRate);
	printf("Byte rate: %d\n", h.ByteRate);
	printf("Block align: %d\n", h.BlockAlign);
	printf("Bits per samle: %d\n", h.BitsPerSample);
	showID("Subchunk 2 ID", h.Subchunk2ID);
	printf("Subchunk 2 size: %d\n", h.Subchunk2Size);
#else
	setColors(RED, bg(BLUE));
	printf("\033[1;1H");
	printf("test.wav            \n");
	setColors(YELLOW, bg(GREEN));
	printf("\033[1;21H");
	printf("Sample rate =%d     \n", h.SampleRate);
	setColors(WHITE, bg(MAGENTA));
	printf("\033[1;61H");
	printf("Duration = %.2f     \n", (float)h.Subchunk2Size/h.ByteRate);
	
#endif
}
void fillID(char *dst, const char *m){
	for(int i =0; i<4; i++)
	*dst++ = *m++;
}

void testTone(int c, int f, float d){
	if(f<30 || f>16000){
		printf("frequency is out of range. \n");
		return;
	}
	if(c<1 || c>2){
		printf("number of channel is not okay\n");
		return;
	}
	if(d<1 || d>10){
		printf("duration is not okay");
		return;
	}
	struct WAVHDR h; // we need to prepare a WAV header
	int samples = d*44100;
	fillID(h.ChunkID, "RIFF");
	fillID(h.Format, "WAVE");
	fillID(h.Subchunk1ID,"fmt ");
	fillID(h.Subchunk2ID,"data");
	h.Subchunk1Size = 16; // for PCM
	h.AudioFormat=1;
	h.NumChannels=c;
	h.SampleRate= 44100;
	h.BitsPerSample=16;

//	if(c==1){ for mono channel
		h.ByteRate = h.SampleRate* c * h.BitsPerSample/8;
		h.BlockAlign = c*h.BitsPerSample/8;
		h.Subchunk2Size = d*h.SampleRate * h.BlockAlign;
		h.ChunkSize = h.Subchunk2Size +36;
//	}
	// prepare sound data
	FILE *fg = fopen("testTone.wav", "w");
        if(fg == NULL) {
                printf("we cannot open the file\n");
                return;
        }
        fwrite(&h, sizeof(h), 1, fg);   // write the header
        for(int i=0; i<d*h.SampleRate; i++) {
                short data = 32767.0*sin(2*PI*i*f/44100);
                fwrite(&data, sizeof(short), 1, fg);
                if(c==2) {
                        short dR = 32767.0*sin(2*PI*i*f/2/44100);
                        fwrite(&dR, sizeof(short), 1, fg);
                }
        }
        fclose(fg);
        printf("test tone is generated\n");
}