edgetrace

Invisible Chroma-DC Watermarking (Prototype). We embed pilots + payload by nudging U/V chroma DC in fixed ROI blocks. Bits repeat across frames; decode uses pilot correlation with polarity flip and majority vote. The current decoder subtracts background (wm−bg). The notebook reports BER pre/post-encode and Δsize for IVF/MKV/WebM to quantify robustness vs. bitrate cost. Deepfake angle (today): this is not yet a cryptographic proof of authenticity. It’s a robustness watermark that lets us run provenance experiments: synthetic/edited segments often degrade the pattern—pilot correlation drops, BER spikes, or bits go missing—providing a practical signal to flag or down-rank at ingest. Roadmap: swap random payload for signed fields (stream ID, timestamp, rolling hash), add near-blind/pairwise decoding (no background), and wire real-time gating with monotonic-time checks.