Sure, I will look more carefully at the docs (i'm at an early stage in using Processing where i really appreciate the more 'fleshed out' explanations this forum provides).
Is it just my machine or is there a problem with the filter_03 example. When I run it it highlight this line;
filter1 = new BiquadFilter(ac, BiquadFilter.BP_SKIRT, 5000.0f, 0.5f);
and prints NullPointerException. I have made sure the drum loop is in the sketch folder..
- // Filter_03.pde
- // in this example, we apply a band-pass filter to a drum loop
- import beads.*;
- AudioContext ac;
- String sourceFile; // this will hold the path to our audio file
- SamplePlayer sp; // the SamplePlayer class will be used to play the audio file
- // standard gain objects
- Gain g;
- Glide gainValue;
- BiquadFilter filter1; // this is our filter unit generator
- void setup()
- {
- size(800, 600);
-
- ac = new AudioContext(); // create our AudioContext
- sourceFile = sketchPath("") + "Drum_Loop_01.wav";
- // Try/Catch blocks will inform us if the file can't be found
- try {
- // initialize our SamplePlayer, loading the file indicated by the sourceFile string
- sp = new SamplePlayer(ac, new Sample(sourceFile));
- }
- catch(Exception e)
- {
- // if there is an error, show an error message (at the bottom of the processing window)
- println("Exception while attempting to load sample!");
- e.printStackTrace(); // then print a technical description of the error
- exit(); // and exit the program
- }
-
- // we would like to play the sample multiple times, so we set KillOnEnd to false
- sp.setKillOnEnd(false);
- filter1 = new BiquadFilter(ac, BiquadFilter.BP_SKIRT, 5000.0f, 0.5f);
- filter1.addInput(sp); // connect the SamplePlayer to the filter
- // as usual, we create a gain that will control the volume of our sample player
- gainValue = new Glide(ac, 0.0, 20);
- g = new Gain(ac, 1, gainValue);
- g.addInput(filter1); // connect the filter to the gain
- ac.out.addInput(g); // connect the Gain to the AudioContext
- ac.start(); // begin audio processing
-
- background(0); // draw a black background
- text("Click to hear a band pass filter with cutoff set to 5000Hz.", 50, 50); // tell the user what to do
- }
- // although we're not drawing to the screen, we need to have a draw function
- // in order to wait for mousePressed events
- void draw(){}
- // this routine is called whenever a mouse button is pressed on the Processing sketch
- void mousePressed()
- {
- gainValue.setValue(0.9);
- sp.setToLoopStart(); // move the playback pointer to the first loop point (0.0)
- sp.start(); // play the audio file
- }
