WebXR LDI Video Player

Please upload an LDI video in quad layout format:
• Top-left: Layer 1 RGB
• Top-right: Layer 1 disparity
• Bottom-left: Layer 2 RGB
• Bottom-right: Layer 2 disparity

Required: Companion JSON file with same base name (e.g., video.mp4 → video.json)
JSON format: {"frame_rate": 30.0, "thresholds": [...]}