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Main Authors: Liang, Yuzhe, Liu, Wenzhe, Qiang, Chunyu, Niu, Zhikang, Chen, Yushen, Ma, Ziyang, Chen, Wenxi, Li, Nan, Zhang, Chen, Chen, Xie
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.20334
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author Liang, Yuzhe
Liu, Wenzhe
Qiang, Chunyu
Niu, Zhikang
Chen, Yushen
Ma, Ziyang
Chen, Wenxi
Li, Nan
Zhang, Chen
Chen, Xie
author_facet Liang, Yuzhe
Liu, Wenzhe
Qiang, Chunyu
Niu, Zhikang
Chen, Yushen
Ma, Ziyang
Chen, Wenxi
Li, Nan
Zhang, Chen
Chen, Xie
contents Flow matching has demonstrated strong generative capabilities and has become a core component in modern Text-to-Speech (TTS) systems. To ensure high-quality speech synthesis, Classifier-Free Guidance (CFG) is widely used during the inference of flow-matching-based TTS models. However, CFG incurs substantial computational cost as it requires two forward passes, which hinders its applicability in real-time scenarios. In this paper, we explore removing CFG from flow-matching-based TTS models to improve inference efficiency, while maintaining performance. Specifically, we reformulated the flow matching training target to directly approximate the CFG optimization trajectory. This training method eliminates the need for unconditional model evaluation and guided tuning during inference, effectively cutting the computational overhead in half. Furthermore, It can be seamlessly integrated with existing optimized sampling strategies. We validate our approach using the F5-TTS model on the LibriTTS dataset. Experimental results show that our method achieves a 9$\times$ inference speed-up compared to the baseline F5-TTS, while preserving comparable speech quality. We will release the code and models to support reproducibility and foster further research in this area.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20334
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Towards Flow-Matching-based TTS without Classifier-Free Guidance
Liang, Yuzhe
Liu, Wenzhe
Qiang, Chunyu
Niu, Zhikang
Chen, Yushen
Ma, Ziyang
Chen, Wenxi
Li, Nan
Zhang, Chen
Chen, Xie
Audio and Speech Processing
Flow matching has demonstrated strong generative capabilities and has become a core component in modern Text-to-Speech (TTS) systems. To ensure high-quality speech synthesis, Classifier-Free Guidance (CFG) is widely used during the inference of flow-matching-based TTS models. However, CFG incurs substantial computational cost as it requires two forward passes, which hinders its applicability in real-time scenarios. In this paper, we explore removing CFG from flow-matching-based TTS models to improve inference efficiency, while maintaining performance. Specifically, we reformulated the flow matching training target to directly approximate the CFG optimization trajectory. This training method eliminates the need for unconditional model evaluation and guided tuning during inference, effectively cutting the computational overhead in half. Furthermore, It can be seamlessly integrated with existing optimized sampling strategies. We validate our approach using the F5-TTS model on the LibriTTS dataset. Experimental results show that our method achieves a 9$\times$ inference speed-up compared to the baseline F5-TTS, while preserving comparable speech quality. We will release the code and models to support reproducibility and foster further research in this area.
title Towards Flow-Matching-based TTS without Classifier-Free Guidance
topic Audio and Speech Processing
url https://arxiv.org/abs/2504.20334