Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?


Failed to load latest commit information.
Latest commit message
Commit time

Python Version Build Status Coverage Status PyPI version MIT License


Voice conversion software - Voice conversion (VC) is a technique to convert a speaker identity of a source speaker into that of a target speaker. This software enables the users to develop a traditional VC system based on a Gaussian mixture model (GMM) and a vocoder-free VC system based on a differential GMM (DIFFGMM) using a parallel dataset of the source and target speakers.

Paper and slide

  • K. Kobayashi, T. Toda, "sprocket: Open-Source Voice Conversion Software," Proc. Odyssey, pp. 203-210, June 2018. [paper]

  • T. Toda, "Hands on Voice Conversion," Speech Processing Courses in Crete (SPCC), July 2018. [slide]

Conversion samples


Reproduce the typical VC systems

This software was developed to make it possible for the users to easily build the VC systems by only preparing a parallel dataset of the desired source and target speakers and executing example scripts. The following VC methods were implemented as the typical VC methods.

Traditional VC method based on GMM

  • T. Toda, A.W. Black, K. Tokuda, "Voice conversion based on maximum likelihood estimation of spectral parameter trajectory," IEEE Transactions on Audio, Speech and Language Processing, Vol. 15, No. 8, pp. 2222-2235, Nov. 2007.

Vocoder-free VC method based on DIFFGMM

  • K. Kobayashi, T. Toda, S. Nakamura, "F0 transformation techniques for statistical voice conversion with direct waveform modification with spectral differential," Proc. IEEE SLT, pp. 693-700, Dec. 2016.

Supply Python3 VC library

To make it possible to easily develop VC-based applications using Python (Python3), the VC library is also supplied, including several interfaces, such as acoustic feature analysis/synthesis, acoustic feature modeling, acoustic feature conversion, and waveform modification. For the details of the VC library, please see sprocket documents in (coming soon).

Installation & Run

Please use Python3.

Current stable version

Ver. 0.18.4

Install sprocket

pip install numpy==1.15.4 cython  # for dependency
pip install sprocket-vc

Run example

See VC example


For any questions or issues please visit:


Copyright (c) 2020 Kazuhiro KOBAYASHI

Released under the MIT license


Thank you @r9y9 and @tats-u for lots of contributions and encouragement helps before release.

Who we are