U-Codec: Ultra Low Frame-rate Neural Speech Codec for Fast High-fidelity Speech Generation

Fuente: arXiv
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Auteurs principaux: Yang, Xusheng, Zhou, Long, Wang, Wenfu, Hu, Kai, Feng, Shulin, Li, Chenxing, Yu, Meng, Yu, Dong, Zou, Yuexian
Format: Preprint
Publié: 2025
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author Yang, Xusheng
Zhou, Long
Wang, Wenfu
Hu, Kai
Feng, Shulin
Li, Chenxing
Yu, Meng
Yu, Dong
Zou, Yuexian
author_facet Yang, Xusheng
Zhou, Long
Wang, Wenfu
Hu, Kai
Feng, Shulin
Li, Chenxing
Yu, Meng
Yu, Dong
Zou, Yuexian
contents We propose \textbf{U-Codec}, an \textbf{U}ltra low frame-rate neural speech \textbf{Codec} that achieves high-fidelity reconstruction and fast speech generation at an extremely low frame-rate of 5Hz (5 frames per second). Extreme compression at 5Hz typically leads to severe intelligibility and spectral detail loss, we introduce a Transformer-based inter-frame long-term dependency module and systematically explore residual vector quantization (RVQ) depth and codebook size to identify optimal configurations. Moreover, we apply U-Codec into a large language model (LLM)-based auto-regressive TTS model, which leverages global and local hierarchical architecture to effectively capture dependencies across multi-layer tokens. We extend LLM-based TTS from 3-layer RVQ at 50Hz to 32-layer RVQ at 5Hz. Experimental results demonstrate that U-Codec improves LLM-based TTS inference speed by around 3 $\times$ over high-frame-rate codecs while maintaining similarity and naturalness. These results validate the feasibility of using highly compressed 5Hz discrete tokens for fast and high-fidelity speech synthesis.
format Preprint
id arxiv_https___arxiv_org_abs_2510_16718
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle U-Codec: Ultra Low Frame-rate Neural Speech Codec for Fast High-fidelity Speech Generation
Yang, Xusheng
Zhou, Long
Wang, Wenfu
Hu, Kai
Feng, Shulin
Li, Chenxing
Yu, Meng
Yu, Dong
Zou, Yuexian
Sound
Computation and Language
Machine Learning
We propose \textbf{U-Codec}, an \textbf{U}ltra low frame-rate neural speech \textbf{Codec} that achieves high-fidelity reconstruction and fast speech generation at an extremely low frame-rate of 5Hz (5 frames per second). Extreme compression at 5Hz typically leads to severe intelligibility and spectral detail loss, we introduce a Transformer-based inter-frame long-term dependency module and systematically explore residual vector quantization (RVQ) depth and codebook size to identify optimal configurations. Moreover, we apply U-Codec into a large language model (LLM)-based auto-regressive TTS model, which leverages global and local hierarchical architecture to effectively capture dependencies across multi-layer tokens. We extend LLM-based TTS from 3-layer RVQ at 50Hz to 32-layer RVQ at 5Hz. Experimental results demonstrate that U-Codec improves LLM-based TTS inference speed by around 3 $\times$ over high-frame-rate codecs while maintaining similarity and naturalness. These results validate the feasibility of using highly compressed 5Hz discrete tokens for fast and high-fidelity speech synthesis.
title U-Codec: Ultra Low Frame-rate Neural Speech Codec for Fast High-fidelity Speech Generation
topic Sound
Computation and Language
Machine Learning
url https://arxiv.org/abs/2510.16718