plectrum

Plectrum: instrument tuner for Android
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Oscilloscope.java (2877B)

      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;
     26 
     27 /**
     28  * The oscilloscope generates a float array with 
     29  * array[i] an x coordinate in percentage
     30  * array[i+1] the value of the amplitude in audio buffer 
     31  * array[i+2] another x coordinate in percentage
     32  * array[i+3] the next amplitude in the audio buffer
     33  * 
     34  * The implementation is based on the one by Dan Ellis found at http://www.ee.columbia.edu/~dpwe/resources/Processing/
     35  * @author Dan Ellis
     36  * @author Joren Six
     37  *
     38  */
     39 public class Oscilloscope implements AudioProcessor {
     40 	public static interface OscilloscopeEventHandler{
     41 		/**
     42 		 * @param data The data contains a float array with: 
     43 		 * array[i] an x coordinate in percentage
     44 		 * array[i+1] the value of the amplitude in audio buffer 
     45 		 * array[i+2] another x coordinate in percentage
     46 		 * array[i+3] the next amplitude in the audio buffer
     47 		 * @param event An audio Event.
     48 		 */
     49 		void handleEvent(float[] data, AudioEvent event);
     50 	}
     51 	float[] dataBuffer;
     52 	private final OscilloscopeEventHandler handler;
     53 	public Oscilloscope(OscilloscopeEventHandler handler){
     54 		this.handler = handler;
     55 	}
     56 	
     57 	@Override
     58 	public boolean process(AudioEvent audioEvent) {
     59 		float[] audioBuffer = audioEvent.getFloatBuffer();
     60 		int offset = 0;
     61 		float maxdx = 0;
     62 		for (int i = 0; i < audioBuffer.length / 4; ++i) {
     63 			float dx = audioBuffer[i + 1] - audioBuffer[i];
     64 			if (dx > maxdx) {
     65 				offset = i;
     66 				maxdx = dx;
     67 			}
     68 		}
     69 		
     70 		float tbase = audioBuffer.length / 2;
     71 		
     72 
     73 		int length = Math.min((int) tbase, audioBuffer.length-offset);
     74 		if(dataBuffer == null || dataBuffer.length != length * 4){
     75 			dataBuffer = new float[length * 4];
     76 		}
     77 		
     78 		int j = 0;
     79 		for(int i = 0; i < length - 1; i++){
     80 		    float x1 = i / tbase;
     81 		    float x2 = i / tbase;
     82 		    dataBuffer[j] = x1;
     83 		    dataBuffer[j+1] = audioBuffer[i+offset];
     84 		    dataBuffer[j+2] = x2;
     85 		    dataBuffer[j+3] = audioBuffer[i+1+offset];
     86 		    j = j + 4;
     87 		}
     88 		handler.handleEvent(dataBuffer, audioEvent);
     89 		return true;
     90 	}
     91 
     92 	@Override
     93 	public void processingFinished() {
     94 	}
     95 
     96 }