做多模态生成或音视频联合建模的团队，终于有了一个能同时优化模态内质量和跨模态对齐的 RL 框架，值得关注其方法论对自家任务的迁移潜力。
OmniNFT 提出了一种面向联合音视频生成的扩散强化学习框架，解决了多目标强化学习中优势不一致、梯度失衡和信用分配不均三大问题。该方法通过模态级优势路由、层级梯度手术和区域级损失重加权，显著提升了音频和视频的感知质量、跨模态对齐和音视频同步。在 JavisBench 和 VBench 基准测试中，基于 LTX-2 骨干的 OmniNFT 实现了全面性能提升。该工作为多模态生成任务中的强化学习应用提供了新范式。
OmniNFT: Modality-wise Omni Diffusion Reinforcement for Joint Audio-Video Generation
Recent advances in joint audio-video generation have been remarkable, yet real-world applications demand strong per-modality fidelity, cross-modal alignment, and fine-grained synchronization. Reinforcement Learning (RL) offers a promising paradigm, but its extension to multi-objective and multi-modal joint audio-video generation remains unexplored. Notably, our in-depth analysis first reveals that the primary obstacles to applying RL in this stem from: (i) multi-objective advantages inconsistency, where the advantages of multimodal outputs are not always consistent within a group; (ii) multi-modal gradients imbalance, where video-branch gradients leak into shallow audio layers responsible for intra-modal generation; (iii) uniform credit assignment, where fine-grained cross-modal alignment regions fail to get efficient exploration. These shortcomings suggest that vanilla RL fine-tuning strategy with a single global advantage often leads to suboptimal results. To address these challenges, we propose OmniNFT, a novel modality-aware online diffusion RL framework with three key innovations: (1) Modality-wise advantage routing, which routes independent per-reward advantages to their respective modality generation branches. (2) Layer-wise gradient surgery, which selectively detaches video-branch gradients on shallow audio layers while retaining those for cross-modal interaction layers. (3) Region-wise loss reweighting, which modulates policy optimization toward critical regions related to audio-video synchronization and fine-grained alignment. Extensive experiments on JavisBench and VBench with the LTX-2 backbone demonstrate that OmniNFT achieves comprehensive improvements in audio and video perceptual quality, cross-modal alignment, and audio-video synchronization.