A cross platform command line utility allowing for time expansion/compression, pitch shifting and resampling of audio.
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README.md

PhaseVocoder

A cross platform command line utility implementing a phase vocoder. The PhaseVocoder allows for time compression/expansion, pitch shifting and resampling of audio with quite a good degree of quality. For audio samples, pre-built executables and additional information please see this page. The PhaseVocoder regularly builds in my continuous integration/release system using Windows 10, OS X (El Capitan) and Linux (Ubuntu 16.04). For building on your platform, please see the steps below.
 

How the PhaseVocoder Works

For information on how the PhaseVocoder works, please see "How the PhaseVocoder Works". Additionally, the PhaseVocoder's quality is dependent on detection of audio transients. Information on how transient detection works can be found here.

 

Build Dependencies

  • Building this project requires CMake version 3.0 or later.

  • Building this project requires a C++14 compliant compiler. This project is routinely built in my continous integration system which uses MS Visual Studio 2017, GCC 5.3.1 and Apple LLVM version 7.3.0 (clang 703.0.31).

  • External dependencies are my AudioLib, GoogleTest and yaml-cpp. You do not need to clone or install these dependencies manually. The GitHub repos will be cloned automatically when CMake runs.

 

Steps for Building

  1. Clone this repo.

  2. Create a new directory at the parallel level as the cloned repo. This directory will hold the project files CMake creates.

  3. cd into this new directory.

  4. From the command line, run cmake -G YourDesiredGeneratorType ../PhaseVocoder/Source

  5. Run make or open the project file in an IDE and build.

 

Usage Examples

Running the PhaseVocoder application from the command line with no arguments will show all possible usage. The following examples show some of the more common usages.

Time Stretching Example - Increase the length of the input by a factor of two:
PhaseVocoder -i in.wav -o out.wav -s 2.0

Time Compression Example - Reduce the length of the input by twenty percent:
PhaseVocoder -input in.wav -output out.wav -stretch 0.8

Pitch Shift Example - Raise the pitch of the audio by 2 semitones:
PhaseVocoder -i in.wav -o out.wav -s -p 2.0

Pitch Shift Example - Drop the pitch of the audio by 3.1 semitones:
PhaseVocoder -i in.wav -o out.wav -s -p -3.1

Resample Example - Change the sample rate to 88,200 Hz:
PhaseVocoder -i in.wav -o out.wav -s -r 88200

 

Tests

Unit test coverage is extensive. You'll notice every component within the source directory has a UT directory which contains unit tests. These of course automatically build and run as part of the build process.

 

Continuous Integration and Automated Release

The Automation directory contains scripts that can be used with Jenkins to setup continuous integration and automated release building of the PhaseVocoder project. These scripts work on Windows, OS X and Linux. For more information on how to setup Jenkins to use these scripts please see this document.

 

Miscellaneous Notes Concerning the Project

  • Currently supports 16 bit wave files as the only form of input.

 

To Do

  • Support various other audio file formats.

 

Licensing

The MIT License applies to this software and its supporting documentation:

Copyright (c) 2017 - Terence M. Darwen - tmdarwen.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.