tobias_platen's blog

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Free software replacement for UTAU nearly completed

In 2011 I discovered UTAU, a proprietary singing synthesizer from Japan that is similar to VOCALOID, but limited to the Japanese language. It is available gratis, has no DRM and it’s voicebank format is documented, but it is still proprietary. It requires a Japanese 8-Bit locale, which is unable to encode European Umlauts. I installed UTAU using Wine, and began to reverse engineer the UST file format, which was really easy for me in this case. I also discovered that the developers of VOCALOID, had released their Spectral Modeling Synthesis Tools as free software under the terms of the GNU GPL. So I wrote a parser for the UST format, and used that parser in my smsUTAU resampler. I also wrote a first replacement for UTAU’s graphical user interface, using the cross platform toolkit Qt.

After I had done my first attempt to replace UTAU, I found two other free software singing synthesizers and a GUI written in Java. I found out that Debian includes Cadencii, which can be used as a replacement for the VOCALOID editor. It was originally written to allow Mac users to run the proprietary VOCALOID software on their incompatible proprietary OS, but it has been ported to GNU/Linux, and it can be used with v.Connect-STAND, an advanced indepedent UTAU resampler that is released under the GNU GPL. The second free singing synthesizer is eCantorix, which lacks a graphical frontend. In the meantime I found out that a group of UTAU users, had released an improved version of my first graphical frontend, but this one did not include a workig synthesizer. They decided to write the program from scratch, using an advanced design. I also found out that Trisquel GNU/Linux incudes Cadencii, but the freedom bugs are not solved until now. Because Cadencii is written in Java, it is extremely inflexible, making it hard to add new features.

In the meantime the QTau devgroup had stopped working on the free software replacements that I had stated in 2011, so I decided to fork their editor and add support for both existing synthesizers (ecantorix and v.Connect-STAND). I began adding new features such as Jack Transport, so that QTau can syncronized with other applications such as Ardour and Rosegarden. I plan to add NSM support in the next release. I created a git repository on and encourage anyone to install the free UTAU replacement. I will publish prebuilt binaries as part of Ongakunix, a Free GNU/Linux distribution with special emphasis on music production. My version of the program only runs on GNU/Linux, there is no support for Windows.

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