~ Pitch Shifting - Implementation in Pure Java with Resampling and Time Stretching

The DSP library for Taros, aptly named TarsosDSP, now includes an implementation of a pitch shifting algorithm (as of version 1.4). The goal of pitch shifting is to change the pitch of a piece of audio without affecting the duration. The algorithm implemented is a combination of resampling and time stretching. Resampling changes the pitch of the audio, but affects the total duration. Consecutively, the duration of the audio is stretched to the original (without affecting pitch) with time stretching. The result is very similar to phase vocoding.

The example application below shows how to pitch shift input from the microphone in real-time, or pitch shift a recorded track with the TarsosDSP library.

Pitch shifting in Java

To test the application, download and execute the PitchShift.jar file and load an audio file. For the moment only 44.1kHz mono wav is allowed. To get started you can try this piece of audio.

There is also a command line interface, the following command lowers the pitch of in.wav by two semitones.

java -jar in.wav out.wav -200

----------------------------------------------------
 _______                       _____   _____ _____  
|__   __|                     |  __ \ / ____|  __ \ 
   | | __ _ _ __ ___  ___  ___| |  | | (___ | |__) |
   | |/ _` | '__/ __|/ _ \/ __| |  | |\___ \|  ___/ 
   | | (_| | |  \__ \ (_) \__ \ |__| |____) | |     
   |_|\__,_|_|  |___/\___/|___/_____/|_____/|_|     
                                                    
----------------------------------------------------
Name:
	TarsosDSP Pitch shifting utility.
----------------------------------------------------
Synopsis:
	java -jar PitchShift.jar source.wav target.wav cents
----------------------------------------------------
Description:
	Change the play back speed of audio without changing the pitch.

		source.wav	A readable, mono wav file.
		target.wav	Target location for the pitch shifted file.
		cents		Pitch shifting in cents: 100 means one semitone up, 
				-100 one down, 0 is no change. 1200 is one octave up.

The resampling feature was implemented with libresample4j by Laszlo Systems. libresample4j is a Java port of Dominic Mazzoni’s libresample 0.1.3, which is in turn based on Julius Smith’s Resample 1.7 library.