Vocal Synthesis Tool UTAU (歌声合成ツール UTAU) is a voice synthesizer program currently available for Windows and Mac OS X systems (the Mac version being named UTAU-Synth), it was developed by Ameya/Ayame. UTAU is a shareware vocal synthesizer program that allows users to create and distribute their own voicebanks. And is viewed as a well-supported alternative to more expensive software that share the same abilities.
UTAU has the advantage of having its development occur at a faster pace. It has plug-in support and users have made a number of plug-ins that greatly improve the software's handling and experience. This support was established fairly early in the software's existence, whereas VOCALOID did not gain this ability until VOCALOID3 in late 2011 and even now it only offers a limited access to source code and plug-in support. Therefore the plug-ins for UTAU can often prove invaluable to users as they can effect the software's results and quality greatly.
Some UTAU voicebanks have been put out as "real" VOCALOIDs, such as the April Fool's joke origins of Kasane Teto. Songs using both UTAU and VOCALOID are also not unheard of. Some users have also began to enforce their copyright ruling over their voicebanks; UTAU or fanmade VOCALOIDs who are guilty of plagiarizing an UTAU's name or using a voicebank without permission risk violating UTAU software agreements and voicebank copyright ownership.
UTAU, meaning "to sing" in Japanese, has its origin in "Jinriki VOCALOID" (人力ボーカロイド, "Manual VOCALOID"), the act of re-editing an existing singing voice, extracting tones as WAV files, and reassembling them. In December 2007, Ameya/Ayame (飴屋／菖蒲), using LOLI.COM's voice samples, released a beta software called Loliedit featuring a simple voicebank called "Loline Com" (a pun on the original voice provider and the "ne" particle originally used on Crypton's products). It features a simple interface with a piano roll, has limited mora (Japanese syllables) and works with a primitive beta engine (or "resampler") later updated on UTAU. This beta software can still be downloaded from Ameya/Ayame's website. In March 2008, Ameya/Ayame released a free, advanced support tool to aid a "Manual VOCALOID" process, called UTAU. In later years, 2010, user feedback and suggestions, as well as other such ideas, lead to the creation of triphone ("VCV"; vowel-consonant-vowel) voicebanks; VOCALOID did not gain this capability until 2011 when VOCALOID3 was released.
The program comes with a default voicebank of 142 samples of Japanese syllables generated from the default voice of A-QUEST's text-to-speech software AquesTalk. Any user can load their own voicebank into UTAU to use. However, without the explicit permission of the voice donor, it is a violation of copyright laws. Those laws protect the rights of any vocalist who may not wish for their voices to be used within the program, such as celebrities. Any music made through this program can be used in the commercial sector. UTAU can be downloaded for free from the home page. It will not run properly on computers which do not support Japanese text or AppLocale.
UTAU is one of the few programs able to convert VOCALOID data files for its own use. It saves data in the .UST (UTAU Sequence text) format and is capable of converting .VSQ files to .UST. However, .UST files itself do not hold as much data as the VOCALOID engines' VSQ or VSQX file extensions, and UTAU does not try to convert many things into even its rough equivalent, only placing the notes. As a result, loss of data may occur. It currently does not support the VOCALOID5 extension, VPR.