A training-free way to shrink the KV cache of autoregressive video generation
AspireAI community · arXiv
Long-horizon autoregressive video diffusion needs a growing KV cache, and existing compression methods make coarse decisions - one shared history selection for a whole generated chunk, historical frames scored only by attention, and head budgets assigned uniformly or by heuristic. This paper shows those decisions are wrong in specific ways: frames within one chunk can depend on different historical frames, the same historical frame scores differently as its temporal distance changes, and masking different heads degrades generation unequally. Focused Forcing is a training-free KV selection method that operates along both the generated-frame and head dimensions, combining attention scores with diversity scores to keep relevant and distinctive history, and giving larger budgets to heads with higher estimated importance. Across multiple autoregressive generation paradigms the authors report up to 1.48x end-to-end acceleration without training, with improved visual quality and text alignment.
Read the story and explore more from the AspireAI community.
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.