There are two projects by Free(B)Soft which QTAU builds on: The Singing Computer and Festival Czech.
The aim of the Singing Computer project is to make another step towards the accessibility of music typesetting to the visually impaired users by introducing the possibility to check the input of lyrics. There is a nice and popular music typesetting tool called LilyPond that is based on a plain text input (similarly as e.g. in the TeX typesetting system). This way of work allows the visually impaired users to input music relatively comfortably in their text editors.
An important part of the music typesetting work is checking the result. This is easy for sighted users who can simply check the output on their screens or printed on the paper. But visually impaired users cannot do that. Even if the accessibility tools were able to describe the positions of notes and lyrics on the screen, checking it in such a way would be very tedious. That means that the visually impaired users have to use other tools.
While it is difficult for the visually impaired users to work with visually represented information, it is usually easy for them to work with information represented in the form of sound. And this is how the music typesetting tools can be customized. LilyPond already solves part of the problem — it offers MIDI output of the music. Listening to it the visually impaired user can check correctness of the music part. But what is still missing is a way to check that the lyrics was input correctly as well. This is what Singing Computer solves.
There original Singing Computer allows, with the help of the Festival speech synthesizer, to make the computer to sing the lyrics written in the LilyPond input file. This way a visually impaired user can check the lyrics and its proper alignment with the notes. The user can detect and correct mistakes made during writing the LilyPond input file. With the help of this tool the music typesetting accessibility becomes almost complete.
The new release (called robotník Utaite), is based on a fork of Sinsy, a Japanese singing voice synthesis system, which is used as a replacement for Festival. Using Sinsy makes it possible to use UTAU and eSpeak voices with a more natural sound and many languages not supported by Festival. You can also use existing Festival or MBROLA voices, future versions may be compatible with NNSVS.