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Let us analyze the Processing code that
implements the Sound Chooser in its salient aspects. The
Sonia.start(this) command is necessary to
activate the Sonia audio engine. The line
Sample
mySample1 declares a variable aimed at containing audio
samples. Several methods can be applied to suchvariable. Among these, the
play methods plays the
sound sample back. In the
draw() code section the
graphic aspect of the applet is defined. Finally, by thefunction
mouseReleased() , we detect when the mouse
is released after being pressed, and where it has beenreleased. At this point a sequenceo of
if conditions finds what instrument/timbre has been selected
according to the clicking point. Moreover, within the function
mouseReleased() the function
filtra(float[]
DATAF, float[]DATA, float RO, float WC) is
invoked. This function, which is implemented in the lastsegment of the code listing, performs a sound
filtering. More precisely, it is a low-pass filter, thus a filter that leavesthe low frequencies unaltered and reduces the intensity of
the high frequencies. According to the radial position of themouse click, the filtering effect changes, being more dramatic
(that is the sound becomes darker) as the mouse is released closer and closer to thecentre.
A lighter realization of the Sound Chooser by means of the library Minim is proposed in problem
[link] . The problem
[link] explores the recent library Beads.
| Trumpet |
| Oboe |
| Violin |
| Flute |
| Applet: choosing a timbre and controlling its brightness |
import pitaru.sonia_v2_9.*;Sample mySample1, mySample2, mySample3, mySample4;
Sample mySample1F, mySample2F, mySample3F, mySample4F;float[] data1, data2, data3, data4;float[] data1F, data2F, data3F, data4F;int sr = 11025; // sampling rate
void setup(){
size(200, 200);colorMode(HSB, 360, height, height);
Sonia.start(this);mySample1 = new Sample("flauto.aif");
mySample2 = new Sample("oboe.wav");mySample3 = new Sample("tromba.wav");
mySample4 = new Sample("violino.wav");mySample1F = new Sample("flauto.aif");
// ... OMISSIS ...data1 = new float[mySample1.getNumFrames()];// creates new arrays the length of the sample
// for the original sound// ... OMISSIS ...
data1F = new float[mySample1.getNumFrames()];
// creates new arrays the length of the sample// for the filtered sound
// ... OMISSIS ...mySample1.read(data1);
// ... OMISSIS ...}
void draw(){
// ... OMISSIS ...}
void mouseReleased(){
float ro;float roLin;
float wc;// FLAUTO
if ((mouseX>95)&&(mouseX<105)&&(mouseY>50)&&(mouseY<90)) {
roLin = (mouseY-49.99)/41;ro = pow(roLin,.33);
wc = 298*(TWO_PI/sr);filtra(data1F, data1, wc, ro);
mySample1F.write(data1F);mySample1F.play();
}// ... OMISSIS ...
}//filtra = new function
void filtra(float[]DATAF, float[] DATA, float WC, float RO) {float G;
float RO2;RO2 = pow(RO, 2);
G = (1-RO)*sqrt(1-2*RO*cos(2*WC)+RO2)*4; // (*4) is for having it louderfor(int i = 3; i<DATA.length; i++){
DATAF[i]= G*DATA[i]+2*RO*cos(WC)*DATAF[i-1]-RO2*DATAF[i-2];//recursive filtering
}}
// safely stop the Sonia engine upon shutdown.public void stop(){
Sonia.stop();super.stop();
} |
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