plectrum

Plectrum: instrument tuner for Android
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RateTransposer.java (2969B)

      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.resample;
     25 
     26 import be.tarsos.dsp.AudioEvent;
     27 import be.tarsos.dsp.AudioProcessor;
     28 
     29 
     30 /**
     31  * Sample rate transposer. Changes sample rate by using  interpolation 
     32  * 
     33  * Together with the time stretcher this can be used for pitch shifting.
     34  * @author Joren Six
     35  */
     36 public class RateTransposer implements AudioProcessor {
     37 
     38 	private double factor;
     39     private Resampler r;
     40     
     41 	/**
     42 	 * Create a new sample rate transposer. The factor determines the new sample
     43 	 * rate. E.g. 0.5 is half the sample rate, 1.0 does not change a thing and
     44 	 * 2.0 doubles the samplerate. If the samples are played at the original
     45 	 * speed the pitch doubles (0.5), does not change (1.0) or halves (0.5)
     46 	 * respectively. Playback length follows the same rules, obviously.
     47 	 * 
     48 	 * @param factor
     49 	 *            Determines the new sample rate. E.g. 0.5 is half the sample
     50 	 *            rate, 1.0 does not change a thing and 2.0 doubles the sample
     51 	 *            rate. If the samples are played at the original speed the
     52 	 *            pitch doubles (0.5), does not change (1.0) or halves (0.5)
     53 	 *            respectively. Playback length follows the same rules,
     54 	 *            obviously.
     55 	 */
     56 	public RateTransposer(double factor){
     57 		this.factor = factor;
     58 		r= new Resampler(false,0.1,4.0);
     59 	}
     60 	
     61 	public void setFactor(double tempo){
     62 		this.factor = tempo;
     63 	}
     64 	
     65 	@Override
     66 	public boolean process(AudioEvent audioEvent) {
     67 		float[] src = audioEvent.getFloatBuffer();
     68 		//Creation of float array in loop could be prevented if src.length is known beforehand...
     69 		//Possible optimization is to instantiate it outside the loop and get a pointer to the 
     70 		//array here, in the process method method.
     71 		float[] out = new float[(int) (src.length * factor)];
     72 		r.process(factor, src, 0, src.length, false, out, 0, out.length);
     73 		//The size of the output buffer changes (according to factor). 
     74 		audioEvent.setFloatBuffer(out);
     75 		//Update overlap offset to match new buffer size
     76 		audioEvent.setOverlap((int) (audioEvent.getOverlap() * factor));
     77 		return true;
     78 	}
     79 
     80 	@Override
     81 	public void processingFinished() {
     82 
     83 	}
     84 
     85 }