将视觉扩散模型框架迁移到文本生成,仅微调结构即达GPT-2水平。
TextLDM: Language Modeling with Continuous Latent Diffusion

- 用VAE将离散词元映射为连续潜变量,结合预训练模型对齐特征
- 在潜空间中进行流匹配训练,生成质量显著优于已有扩散语言模型
- 首次证明视觉扩散架构可有效迁移至语言建模,适合多模态统一架构研究
扩散Transformer(DiT)在变分自编码器(VAE)潜空间中通过流匹配实现图像与视频的统一生成。将该框架扩展至语言建模,是迈向统一生成与理解架构的关键一步。我们提出TextLDM,将视觉潜扩散方法迁移至文本生成,仅做最小化结构修改:基于Transformer的VAE将离散词元映射为连续潜变量,并通过与冻结的预训练语言模型对齐的表示对齐(REPA)提升潜变量质量;随后标准DiT在该潜空间执行流匹配,架构与视觉版本完全一致。核心挑战在于获取高质量连续文本表示——我们发现重建保真度不足,必须通过REPA对齐预训练语言模型特征才能保障下游生成质量。在OpenWebText2上从零训练,TextLDM显著优于先前扩散语言模型,并在相同设置下达到GPT-2水平。结果表明,视觉DiT范式可有效迁移至语言建模,为多模态生成与理解的统一扩散架构迈出关键一步。
原文摘要 · Abstract (English)
Diffusion Transformers (DiT) trained with flow matching in a VAE latent space have unified visual generation across images and videos. A natural next step toward a single architecture for both generation (visual synthesis) and understanding (text generation) is to apply this framework to language modeling. We propose TextLDM, which transfers the visual latent diffusion recipe to text generation with minimal architectural modification. A Transformer-based VAE maps discrete tokens to continuous latents, enhanced by Representation Alignment (REPA) with a frozen pretrained language model to produce representations effective for conditional denoising. A standard DiT then performs flow matching in this latent space, identical in architecture to its visual counterpart. The central challenge we address is obtaining high-quality continuous text representations: we find that reconstruction fidelity alone is insufficient, and that aligning latent features with a pretrained language model via REPA is critical for downstream generation quality. Trained from scratch on OpenWebText2, TextLDM substantially outperforms prior diffusion language models and matches GPT-2 under the same settings. Our results establish that the visual DiT recipe transfers effectively to language, taking a concrete step toward unified diffusion architectures for multimodal generation and understanding.
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