plectrum

Plectrum: instrument tuner for Android
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DelayEffect.java (3159B)

      1 /*
      2 *      _______                       _____   _____ _____  
      3 *     |__   __|                     |  __ \ / ____|  __ \ 
      4 *        | | __ _ _ __ ___  ___  ___| |  | | (___ | |__) |
      5 *        | |/ _` | '__/ __|/ _ \/ __| |  | |\___ \|  ___/ 
      6 *        | | (_| | |  \__ \ (_) \__ \ |__| |____) | |     
      7 *        |_|\__,_|_|  |___/\___/|___/_____/|_____/|_|     
      8 *                                                         
      9 * -------------------------------------------------------------
     10 *
     11 * TarsosDSP is developed by Joren Six at IPEM, University Ghent
     12 *  
     13 * -------------------------------------------------------------
     14 *
     15 *  Info: http://0110.be/tag/TarsosDSP
     16 *  Github: https://github.com/JorenSix/TarsosDSP
     17 *  Releases: http://0110.be/releases/TarsosDSP/
     18 *  
     19 *  TarsosDSP includes modified source code by various authors,
     20 *  for credits and info, see README.
     21 * 
     22 */
     23 
     24 
     25 package be.tarsos.dsp.effects;
     26 
     27 import be.tarsos.dsp.AudioEvent;
     28 import be.tarsos.dsp.AudioProcessor;
     29 
     30 
     31 /**
     32  * <p>
     33  * Adds an echo effect to the signal.
     34  * </p>
     35  * 
     36  * @author Joren Six
     37  */
     38 public class DelayEffect implements AudioProcessor {
     39 	
     40 	private double sampleRate;
     41 	private float[] echoBuffer;//in seconds
     42 	private int position;
     43 	private float decay;
     44 	
     45 	private double newEchoLength;
     46 	
     47 	/**
     48 	 * @param echoLength in seconds
     49 	 * @param sampleRate the sample rate in Hz.
     50 	 * @param decay The decay of the echo, a value between 0 and 1. 1 meaning no decay, 0 means immediate decay (not echo effect).
     51 	 */
     52 	public DelayEffect(double echoLength,double decay,double sampleRate) {
     53 		this.sampleRate = sampleRate;
     54 		setDecay(decay);
     55 		setEchoLength(echoLength);
     56 		applyNewEchoLength();	
     57 	}
     58 	
     59 	/**
     60 	 * @param newEchoLength A new echo buffer length in seconds.
     61 	 */
     62 	public void setEchoLength(double newEchoLength){
     63 		this.newEchoLength = newEchoLength;
     64 	}
     65 	
     66 	private void applyNewEchoLength(){
     67 		if(newEchoLength != -1){
     68 			
     69 			//create a new buffer with the information of the previous buffer
     70 			float[] newEchoBuffer = new float[(int) (sampleRate * newEchoLength)];
     71 			if(echoBuffer != null){
     72 				for(int i = 0 ; i < newEchoBuffer.length; i++){
     73 					if(position >= echoBuffer.length){
     74 						position = 0;
     75 					}
     76 					newEchoBuffer[i] = echoBuffer[position];
     77 					position++;
     78 				}
     79 			}
     80 			this.echoBuffer = newEchoBuffer;
     81 			newEchoLength = -1;
     82 		}
     83 	}
     84 	
     85 	/**
     86 	 * A decay, should be a value between zero and one.
     87 	 * @param newDecay the new decay (preferably between zero and one).
     88 	 */
     89 	public void setDecay(double newDecay){
     90 		this.decay = (float) newDecay;
     91 	}
     92 	
     93 	@Override
     94 	public boolean process(AudioEvent audioEvent) {
     95 		float[] audioFloatBuffer = audioEvent.getFloatBuffer();
     96 		int overlap = audioEvent.getOverlap();
     97 			
     98 		for(int i = overlap ; i < audioFloatBuffer.length ; i++){
     99 			if(position >= echoBuffer.length){
    100 				position = 0;
    101 			}
    102 			
    103 			//output is the input added with the decayed echo 		
    104 			audioFloatBuffer[i] = audioFloatBuffer[i] + echoBuffer[position] * decay;
    105 			//store the sample in the buffer;
    106 			echoBuffer[position] = audioFloatBuffer[i];
    107 			
    108 			position++;
    109 		}
    110 		
    111 		applyNewEchoLength();
    112 		
    113 		return true;
    114 	}
    115 
    116 	@Override
    117 	public void processingFinished() {		
    118 	}
    119 }