Julius is a speech recognition engine, specifically a high-performance, two-pass large vocabulary continuous speech recognition (LVCSR) decoder software for speech-related researchers and developers.
It can perform almost real-time computing (RTC) decoding on most current personal computers (PCs) in 60k word dictation task using word trigram (3-gram) and context-dependent Hidden Markov model (HMM).
Julian is a modified version of Julius that uses hand-designed type of finite-state machine (FSM) termed a deterministic finite automaton (DFA) grammar as a language model.
Julius adopts acoustic models in Hidden Markov Model Toolkit (HTK) ASCII format, pronunciation dictionary in HTK-like format, and word 3-gram language models in ARPA standard format: forward 2-gram and reverse 3-gram as trained from speech corpus with reversed word order.
In April 2018, thanks to the effort of Mozilla foundation, a 350-hour audio corpus of spoken English was made available.