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RESEARCH PAPER / 2025-10-31

LongCat-Flash-Omni Technical Report

Meituan LongCat Team, Bairui Wang, Bayan ...Full author list in the original paper.

Meituan LongCat Team · arXiv

Affiliations: Meituan LongCat Team

Abstract

We introduce LongCat-Flash-Omni, a state-of-the-art open-source omni-modal model with 560 billion parameters, excelling at real-time audio-visual interaction. By adopting a curriculum-inspired progressive training strategy that transitions from simpler to increasingly complex modality sequence modeling tasks, LongCat-Flash-Omni attains comprehensive multimodal capabilities while maintaining strong unimodal capability. Building upon LongCat-Flash, which adopts a high-performance Shortcut-connected Mixture-of-Experts (MoE) architecture with zero-computation experts, LongCat-Flash-Omni integrates efficient multimodal perception and speech reconstruction modules. Despite its immense size of 560B parameters (with 27B activated), LongCat-Flash-Omni achieves low-latency real-time audio-visual interaction. For training infrastructure, we developed a modality-decoupled parallelism scheme specifically designed to manage the data and model heterogeneity inherent in large-scale multimodal training. This innovative approach demonstrates exceptional efficiency by sustaining over 90% of the throughput achieved by text-only training. Extensive evaluations show that LongCat-Flash-Omni achieves state-of-the-art performance on omni-modal benchmarks among open-source models. Furthermore, it delivers highly competitive results across a wide range of modality-specific tasks, including text, image, and video understanding, as well as audio understanding and generation. We provide a comprehensive overview of the model architecture design, training procedures, and data strategies, and open-source the model to foster future research and development in the community.

The following analysis is generated by AI and may contain errors. It is separate from the authors’ abstract and is not peer review.

Research summary

The main contribution of this paper is the introduction of LongCat-Flash-Omni, a state-of-the-art omni-modal model that integrates advanced training strategies and architectural innovations to achieve efficient real-time audio-visual interaction. This work significantly advances the field of multimodal machine learning by providing a comprehensive framework for integrating diverse modalities while maintaining high performance and low latency.

Methodology

The methodology presented in this paper is robust, leveraging a curriculum-inspired progressive training strategy that effectively addresses the challenges of integrating multiple modalities. The use of a Shortcut-connected Mixture-of-Experts (MoE) architecture with zero-computation experts is innovative, allowing for efficient processing of 560 billion parameters while maintaining low latency. The modality-decoupled parallelism scheme is a significant contribution, enhancing training efficiency in a multimodal context. The paper also details a comprehensive approach to data curation and training across various modalities, which is critical for the model's performance.

Results & evaluation

The paper provides extensive evaluations demonstrating state-of-the-art performance on several omni-modal benchmarks, including Omni-Bench and WorldSense. The results indicate that the model not only excels in multimodal tasks but also retains competitive performance in unimodal tasks. However, the paper lacks detailed quantitative results and comparisons with existing models, which would strengthen the claims of superiority.

Reproducibility

The authors have made efforts to enhance reproducibility by open-sourcing the model and providing a comprehensive overview of the architecture, training procedures, and data strategies. However, the paper could benefit from more detailed descriptions of the experimental setups and hyperparameter tuning processes to facilitate replication.

Limitations

One limitation is the model's size, which may pose challenges for deployment in resource-constrained environments. Additionally, while the paper mentions low-latency performance, it does not provide sufficient benchmarks or comparisons to quantify this claim effectively. The reliance on large-scale data curation may also introduce biases depending on the quality and diversity of the datasets used.

Broader impact

The potential applications of LongCat-Flash-Omni are vast, ranging from enhanced human-AI interaction systems to advancements in multimodal understanding in various domains such as education, entertainment, and accessibility. By fostering an open-source approach, the authors contribute to the community's capacity for further research and development in omni-modal intelligence. The main contribution of this paper is the introduction of LongCat-Flash-Omni, a state-of-the-art omni-modal model that integrates advanced training strategies and architectural innovations to achieve efficient real-time audio-visual interaction. This work significantly advances the field of multimodal machine learning by providing a comprehensive framework for integrating diverse modalities while maintaining high performance and low latency.

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