Rocaloid is an open source [vocal-synthesis] project created by [sleepwalking], heavily inspired by [vocaloid] and [utau]. Main source code on Github: https://github.com/Rocaloid
This project is definitely obsolete and 6-7 years since last updated at the time of writing. It seems to have been created by [sleepwalking] and others during his time at university.
Whitepaper-type thing going over design, goals, infrastructure, and some history: https://rocaloid.github.io/resources/publications/Introduction-20140614.pdf
Sleepwalking has a recorded TED talk video going over his learning + experiences building this software: https://www.youtube.com/watch?v=wb_kHCtudMk