Netease Youdao (Daniel Huang et al.) · Stable-Prefix Streaming ASR

Confucius4-R2T2

Confucius4-R2T2 is a streaming speech recognition model that never revises its earlier output, built by post-training Qwen3-ASR-1.7B on 1,500 hours of Chinese and English audio with the audio encoder and projector frozen. It introduces the Longest Stable Prefix concept, which the authors prove is monotone and consistent with full-audio output, so no architectural change is needed. The authors report streaming quality close to the base model's full-context accuracy with stable text and low emission lag, and state that the model weights and code are open-sourced on Hugging Face and GitHub.