# IndexTTS: An Industrial-Level Controllable and Efficient Zero-Shot Text-To-Speech System arXiv: https://arxiv.org/abs/2502.05512 ยท HTML: https://mlsanity.com/paper/2502.05512/ ## Key facts - Cited by 28 papers in the map (data through 14 Oct 2026). - Builds on 20 of its 22 references that are in the map. - First posted on arXiv 8 Feb 2025. ## Builds on (most cited first, 20 of 20) - [Neural Discrete Representation Learning](https://mlsanity.com/paper/1711.00937/) (2017) - [Robust Speech Recognition via Large-Scale Weak Supervision](https://mlsanity.com/paper/2212.04356/) (2022) - [Common Voice: A Massively-Multilingual Speech Corpus](https://mlsanity.com/paper/1912.06670/) (2019) - [HiFi-GAN: Generative Adversarial Networks for Efficient and High Fidelity Speech Synthesis](https://mlsanity.com/paper/2010.05646/) (2020) - [Neural Codec Language Models are Zero-Shot Text to Speech Synthesizers](https://mlsanity.com/paper/2301.02111/) (2023) - [Finite Scalar Quantization: VQ-VAE Made Simple](https://mlsanity.com/paper/2309.15505/) (2023) - [AISHELL-1: An Open-Source Mandarin Speech Corpus and A Speech Recognition Baseline](https://mlsanity.com/paper/1709.05522/) (2017) - [F5-TTS: A Fairytaler that Fakes Fluent and Faithful Speech with Flow Matching](https://mlsanity.com/paper/2410.06885/) (2024) - [CosyVoice: A Scalable Multilingual Zero-shot Text-to-speech Synthesizer based on Supervised Semantic Tokens](https://mlsanity.com/paper/2407.05407/) (2024) - [Seed-TTS: A Family of High-Quality Versatile Speech Generation Models](https://mlsanity.com/paper/2406.02430/) (2024) - [CosyVoice 2: Scalable Streaming Speech Synthesis with Large Language Models](https://mlsanity.com/paper/2412.10117/) (2024) - [YourTTS: Towards Zero-Shot Multi-Speaker TTS and Zero-Shot Voice Conversion for everyone](https://mlsanity.com/paper/2112.02418/) (2021) - [BigVGAN: A Universal Neural Vocoder with Large-Scale Training](https://mlsanity.com/paper/2206.04658/) (2022) - [XTTS: a Massively Multilingual Zero-Shot Text-to-Speech Model](https://mlsanity.com/paper/2406.04904/) (2024) - [Matcha-TTS: A fast TTS architecture with conditional flow matching](https://mlsanity.com/paper/2309.03199/) (2023) - [Paraformer: Fast and Accurate Parallel Transformer for Non-autoregressive End-to-End Speech Recognition](https://mlsanity.com/paper/2206.08317/) (2022) - [FireRedTTS: A Foundation Text-To-Speech Framework for Industry-Level Generative Speech Applications](https://mlsanity.com/paper/2409.03283/) (2024) - [Better speech synthesis through scaling](https://mlsanity.com/paper/2305.07243/) (2023) - [Demucs: Deep Extractor for Music Sources with extra unlabeled data remixed](https://mlsanity.com/paper/1909.01174/) (2019) - [Fish-Speech: Leveraging Large Language Models for Advanced Multilingual Text-to-Speech Synthesis](https://mlsanity.com/paper/2411.01156/) (2024) ## Built on by (most cited first, 28 of 28) - [CosyVoice 3: Towards In-the-wild Speech Generation via Scaling-up and Post-training](https://mlsanity.com/paper/2505.17589/) (2025) - [IndexTTS2: A Breakthrough in Emotionally Expressive and Duration-Controlled Auto-Regressive Zero-Shot Text-to-Speech](https://mlsanity.com/paper/2506.21619/) (2025) - [OmniVoice: Towards Omnilingual Zero-Shot Text-to-Speech with Diffusion Language Models](https://mlsanity.com/paper/2604.00688/) (2026) - [ZipVoice-Dialog: Non-Autoregressive Spoken Dialogue Generation with Flow Matching](https://mlsanity.com/paper/2507.09318/) (2025) - [Step-Audio-EditX Technical Report](https://mlsanity.com/paper/2511.03601/) (2025) - [IndexTTS 2.5 Technical Report](https://mlsanity.com/paper/2601.03888/) (2026) - [dots.tts Technical Report](https://mlsanity.com/paper/2606.07080/) (2026) - [DiSTAR: Diffusion over a Scalable Token Autoregressive Representation for Speech Generation](https://mlsanity.com/paper/2510.12210/) (2025) - [Sparse Autoencoders for Interpretable Emotion Control in Text-to-Speech](https://mlsanity.com/paper/2606.01479/) (2026) - [UDDETTS: Unifying Discrete and Dimensional Emotions for Controllable Emotional Text-to-Speech](https://mlsanity.com/paper/2505.10599/) (2025) - [UniTTS: An end-to-end TTS system without decoupling of acoustic and semantic information](https://mlsanity.com/paper/2505.17426/) (2025) - [Unifying Speech Recognition, Synthesis and Conversion with Autoregressive Transformers](https://mlsanity.com/paper/2601.10770/) (2026) - [Towards Human-Like Interactive Speech Recognition With Agentic Correction and Semantic Evaluation](https://mlsanity.com/paper/2605.29430/) (2026) - [CloneShield: A Framework for Universal Perturbation Against Zero-Shot Voice Cloning](https://mlsanity.com/paper/2505.19119/) (2025) - [Interactive ASR: Towards Human-Like Interaction and Semantic Coherence Evaluation for Agentic Speech Recognition](https://mlsanity.com/paper/2604.09121/) (2026) - [AgentSteerTTS: A Multi-Agent Closed-Loop Framework for Composite-Instruction Text-to-Speech](https://mlsanity.com/paper/2605.17583/) (2026) - [Robust Residual Finite Scalar Quantization for Neural Compression](https://mlsanity.com/paper/2508.15860/) (2025) - [EchoFake: A Replay-Aware Dataset for Practical Speech Deepfake Detection](https://mlsanity.com/paper/2510.19414/) (2025) - [E2E-VGuard: Adversarial Prevention for Production LLM-based End-To-End Speech Synthesis](https://mlsanity.com/paper/2511.07099/) (2025) - [Controllable Dysarthric Speech Synthesis with Patient-Specific Conditioning for Speaker-Diverse ASR Augmentation](https://mlsanity.com/paper/2602.08696/) (2026) - [WAND: Windowed Attention and Knowledge Distillation for Efficient Autoregressive Text-to-Speech Models](https://mlsanity.com/paper/2604.08558/) (2026) - [AST: Adaptive, Seamless, and Training-Free Precise Speech Editing](https://mlsanity.com/paper/2604.16056/) (2026) - [PilotTTS: A Disciplined Modular Recipe for Competitive Speech Synthesis](https://mlsanity.com/paper/2605.27258/) (2026) - [Read What You Hear: Reference-Free Hypotheses Evaluation with Acoustic Discrepancy](https://mlsanity.com/paper/2606.04680/) (2026) - [UniSAE: Unified Speech Attribute Editing on Speaker, Emotion and Low-Level Content via Discrete Phonetic Posteriorgram Modelling](https://mlsanity.com/paper/2606.31128/) (2026) - [CookVoice: Unified Framework for Style Controllable Multi-Modal Human Voice Generation](https://mlsanity.com/paper/2608.11590/) (2026) - [Confucius4-TTS: Transcript-Free Cross-Lingual Zero-Shot TTS with a Learnable Speaker Encoder](https://mlsanity.com/paper/2608.11650/) (2026) - [Tacit-TTS: From Autoregressive Decoding to Masked Prediction for Efficient Transcript-Free Voice Cloning](https://mlsanity.com/paper/2609.38658/) (2026) ## Abstract (arXiv) Recently, large language model (LLM) based text-to-speech (TTS) systems have gradually become the mainstream in the industry due to their high naturalness and powerful zero-shot voice cloning capabilities.Here, we introduce the IndexTTS system, which is mainly based on the XTTS and Tortoise model. We add some novel improvements. Specifically, in Chinese scenarios, we adopt a hybrid modeling method that combines characters and pinyin, making the pronunciations of polyphonic characters and long-tail characters controllable. We also performed a comparative analysis of the Vector Quantization (VQ) with Finite-Scalar Quantization (FSQ) for codebook utilization of acoustic speech tokens. To further enhance the effect and stability of voice cloning, we introduce a conformer-based speech conditional encoder and replace the speechcode decoder with BigVGAN2. Compared with XTTS, it has achieved significant improvements in naturalness, content consistency, and zero-shot voice cloning. As for the popular TTS systems in the open-source, such as Fish-Speech, CosyVoice2, FireRedTTS and F5-TTS, IndexTTS has a relatively simple training process, more controllable usage, and faster inference speed. Moreover, its performance surpasses that of these systems. Our demos are available at https://index-tts.github.io.