Aletheia: Physics-Conditioned Localized Artifact Attention (PhyLAA-X) for End-to-End Generalizable and Robust Deepfake Video Detection
Organizations: Researcher, Aletheia Project
Abstract
State-of-the-art deepfake detectors achieve near-perfect in-domain accuracy yet degrade under cross-generator shifts, heavy compression, and adversarial perturbations. The core limitation remains the decoupling of semantic artifact learning from physical invariants: optical-flow discontinuities, specular-reflection inconsistencies, and cardiac-modulated reflectance (rPPG) are treated either as post-hoc features or ignored. We introduce PhyLAA-X, a novel physics-conditioned extension of Localized Artifact Attention (LAA-X). PhyLAA-X injects three end-to-end differentiable physics-derived feature volumes - optical-flow curl, specular-reflectance skewness, and spatially-upsampled rPPG power spectra - directly into the LAA-X attention computation via cross-attention gating and a resonance consistency loss. This forces the network to learn manipulation boundaries where semantic inconsistencies and physical violations co-occur - regions inherently harder for generative models to replicate consistently. PhyLAA-X is embedded across an efficient spatiotemporal ensemble (EfficientNet-B4+BiLSTM, ResNeXt-101+Transformer, Xception+causal Conv1D) with uncertainty-aware adaptive weighting. On FaceForensics++ (c23), Aletheia reaches 97.2% accuracy / 0.992 AUC-ROC; on Celeb-DF v2, 94.9% / 0.981; on DFDC, 90.8% / 0.966 - outperforming the strongest published baseline (LAA-Net [1]) by 4.1-7.3% in cross-generator settings and maintaining 79.4% accuracy under epsilon = 0.02 PGD-10 attacks. Single-backbone ablations confirm PhyLAA-X alone delivers a 4.2% cross-dataset AUC gain. The full production system is open-sourced at https://github.com/devghori1264/Aletheia (v1.2, April 2026) with pretrained weights, the adversarial corpus (referred to as ADC-2026 in this work), and complete reproducibility artifacts.
Figures & tables
| Method | FF++ c23 | FF++ c40 | Celeb-DF | DFDC | WildDeepfake | Avg. Cross |
|---|---|---|---|---|---|---|
| Xception baseline | 0.979 | 0.942 | 0.965 | 0.941 | 0.812 | 0.890 |
| LAA-Net [ 1 ] | 0.987 | 0.958 | 0.972 | 0.955 | 0.841 | 0.919 |
| DF40 baseline [ 2 ] | 0.990 | 0.950 | 0.975 | 0.960 | 0.853 | 0.927 |
| Aletheia (Ours) | 0.992 | 0.968 | 0.981 | 0.966 | 0.889 | 0.951 |
| Attack ( ) | Undefended Acc | +Input Trans. | +PhyLAA-X Only | Full Aletheia |
|---|---|---|---|---|
| FGSM | 48.7% | 71.2% | 76.4% | 82.1% |
| PGD-10 | 41.2% | 65.9% | 73.8% | 79.4% |
| Transfer | — | — | — | 74.6% |
Deepfake Detection
Deepfake detection identifies manipulated or AI-generated media to support trustworthy communication, identity verification, and forensic analysis.
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