plectrum

Plectrum: instrument tuner for Android
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ZeroCrossingRateProcessor.java (1555B)

      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 package be.tarsos.dsp;
     25 
     26 /**
     27  * Calculates the zero crossing rate for a frame.
     28  * @author Joren Six
     29  *
     30  */
     31 public class ZeroCrossingRateProcessor implements AudioProcessor{
     32 
     33 	private float zeroCrossingRate = 0;
     34 	@Override
     35 	public boolean process(AudioEvent audioEvent) {
     36 		float[] buffer = audioEvent.getFloatBuffer();
     37 		
     38 		int numberOfZeroCrossings = 0;
     39 		for(int i = 1 ; i < buffer.length ; i++){
     40 			if(buffer[i] * buffer[i-1] < 0){
     41 				numberOfZeroCrossings++;
     42 			}
     43 		}
     44 		
     45 		zeroCrossingRate = numberOfZeroCrossings / (float) (buffer.length - 1);
     46 		
     47 		return true;
     48 	}
     49 	
     50 	public float getZeroCrossingRate(){
     51 		return zeroCrossingRate;
     52 	}
     53 
     54 	@Override
     55 	public void processingFinished() {
     56 	}
     57 
     58 }