Sparse-vDiT: Unleashing the Power of Sparse Attention to Accelerate
  Video Diffusion Transformers
Authors: name: Pengtao Chen, name: Xianfang Zeng, name: Maosen Zhao, name: Peng Ye, name: Mingzhu Shen, name: Wei Cheng, name: Gang Yu, name: Tao Chen

While Diffusion Transformers (DiTs) have achieved breakthroughs in video
generation, this long sequence generation task remains constrained by the
quadratic complexity of attention mechanisms, resulting in significant
inference latency. Through detailed analysis of attention maps in Video
Diffusion Transformer (vDiT), we identify three recurring sparsity patterns:
diagonal, multi-diagonal, and vertical-stripe structures. And even 3-6\%
attention heads can be skipped. Crucially, these patterns exhibit strong
layer-depth and head-position correlations but show limited dependence on the
input content. Leveraging these findings, we propose Sparse-vDiT, a sparsity
acceleration framework for vDiT comprising: 1) Pattern-optimized sparse kernels
that replace dense attention with computationally efficient implementations for
each identified sparsity pattern. 2) An offline sparse diffusion search
algorithm that selects the optimal sparse computation strategy per layer and
head via hardware-aware cost modeling. After determining the optimal
configuration, we fuse heads within the same layer that share the same
attention strategy, enhancing inference efficiency. Integrated into
state-of-the-art vDiT models (CogVideoX1.5, HunyuanVideo, and Wan2.1),
Sparse-vDiT achieves 2.09times, 2.38times, and 1.67times theoretical
FLOP reduction, and actual inference speedups of 1.76times, 1.85times,
and 1.58times, respectively, while maintaining high visual fidelity, with
PSNR values reaching 24.13, 27.09, and 22.59. Our work demonstrates that latent
structural sparsity in vDiTs can be systematically exploited for long video
synthesis.