errormsg synth_electricorgan(CAudioData**out,double basefreq, double lengthSeconds, double amp)
{
CAudioData* audio;
audio = *out = caudiodata_new(); //use audio as an alias for the output, *out.
if (lengthSeconds<0) return "Invalid length";
if (basefreq<=0) return "Invalid frequency";
int length = (int)(lengthSeconds * SampleRate);
errormsg msg = caudiodata_allocate(audio, length, 1, SampleRate);
if (msg!=OK) return msg;
//OscillatorFn fn = (OscillatorFn) sin;
//make sure all set to 0
int i;
for (i=0; i<audio->length; i++) audio->data[i] = 0;
int n;
for(n=0; n<8; n++)
{
double freq1 = basefreq*(n+1);
double freq2 = (basefreq*1.00606)*(n+1);
double weight = (n==0) ? pow(0.9, 8 - 1) : 0.1 * pow(0.9, 8 - n); //or 8-1 ?
double timescale1 = freq1 * 2.0 * PI / (double) SampleRate;
double timescale2 = freq2 * 2.0 * PI / (double) SampleRate;
for (i=0; i<audio->length; i++)
audio->data[i] += amp*0.5*weight*(sin(i*timescale1)+sin(i*timescale2));
}
return OK;
}
caudiodata_void example1()
{
//create a sample sine wave.
CAudioData* audio = caudiodata_new();
errormsg msg = caudiodata_allocate(audio, 44100*4, 1, 44100); // 4 seconds of audio, mono.
if (msg!=OK) puts(msg);
double freq = 300;
int i;
for (i = 0; i < audio->length; i++)
{
audio->data[i] = 0.9 * sin(i * freq * 2.0 * PI / (double)audio->sampleRate);
}
FILE * f = fopen("out.wav", "wb");
msg = caudiodata_savewave(audio, f, 16);
if (msg != OK) puts(msg);
fclose(f);
caudiodata_dispose( audio);
}
// Intentional beat frequencies "smoothen" the sound and make it more musical.
errormsg synth_sineorgan(CAudioData**out,double freq, double lengthSeconds, double amp)
{
CAudioData* audio;
audio = *out = caudiodata_new(); //use audio as an alias for the output, *out.
if (lengthSeconds<0) return "Invalid length";
if (freq<=0) return "Invalid frequency";
int length = (int)(lengthSeconds * SampleRate);
errormsg msg = caudiodata_allocate(audio, length, 1, SampleRate);
if (msg!=OK) return msg;
CAudioData* w1;
CAudioData* w2;
synth_sin(&w1, freq, lengthSeconds, amp);
synth_sin(&w2, freq* 1.0006079, lengthSeconds, amp);
int i;
for(i=0; i<audio->length; i++)
audio->data[i] = 0.6*w1->data[i] + 0.4*w2->data[i];
caudiodata_dispose(w1);
caudiodata_dispose(w2);
return OK;
}
