{
  "requested_second": 130,
  "exact_baseline_frame": {
    "id": "f3900",
    "source_frame_index": 3900,
    "timestamp_seconds": 130.0,
    "source_pts_seconds": 130.0,
    "timestamp": "130.000000",
    "reasons": [
      "baseline_1fps"
    ],
    "image": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003900.webp",
    "width": 405,
    "height": 720,
    "selection_reasons": [
      "baseline_1fps_or_last"
    ],
    "source_width": 720,
    "source_height": 1280,
    "image_url": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003900.webp"
  },
  "nearby_frames": [
    {
      "id": "f3870",
      "source_frame_index": 3870,
      "timestamp_seconds": 129.0,
      "source_pts_seconds": 129.0,
      "timestamp": "129.000000",
      "reasons": [
        "baseline_1fps"
      ],
      "image": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003870.webp",
      "width": 405,
      "height": 720,
      "selection_reasons": [
        "baseline_1fps_or_last"
      ],
      "source_width": 720,
      "source_height": 1280,
      "image_url": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003870.webp"
    },
    {
      "id": "f3900",
      "source_frame_index": 3900,
      "timestamp_seconds": 130.0,
      "source_pts_seconds": 130.0,
      "timestamp": "130.000000",
      "reasons": [
        "baseline_1fps"
      ],
      "image": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003900.webp",
      "width": 405,
      "height": 720,
      "selection_reasons": [
        "baseline_1fps_or_last"
      ],
      "source_width": 720,
      "source_height": 1280,
      "image_url": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003900.webp"
    },
    {
      "id": "f3930",
      "source_frame_index": 3930,
      "timestamp_seconds": 131.0,
      "source_pts_seconds": 131.0,
      "timestamp": "131.000000",
      "reasons": [
        "baseline_1fps"
      ],
      "image": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003930.webp",
      "width": 405,
      "height": 720,
      "selection_reasons": [
        "baseline_1fps_or_last"
      ],
      "source_width": 720,
      "source_height": 1280,
      "image_url": "https://ai-video-relay-check-20261027.pages.dev/frames/frame-00003930.webp"
    }
  ],
  "screen_observation": {
    "time": 130.0,
    "source_frame_index": 3900,
    "raw_ocr": "",
    "raw_caption": "",
    "raw_title": "",
    "screen_caption": "",
    "screen_title": "",
    "reviewed_changes": [],
    "verification": "automatic OCR; not independently verified",
    "timing": "observed frame time; onset/offset not known to subsecond precision",
    "is_confirmed_speech": false
  },
  "raw_ASR_at_estimated_time": [],
  "content_section": {
    "index": 15,
    "start": 127.7,
    "end": 137.5,
    "title": "俯拍搅拌车",
    "visual_observation": "从高处看搅拌车及周围土路、树木；车体位置有小幅变化。",
    "camera": "高位俯拍，画面主体是车辆。",
    "uncertainty": "静帧不足以确认材料流向或车辆操作意图。",
    "provenance": "assistant visual review of source-frame sheets; not an independent human or automatic semantic-model benchmark"
  },
  "unknowns": [
    "ASR not a verified listening transcript",
    "Caption display time can differ from speech time",
    "Assistant observation must be cross-checked by actually opening image"
  ]
}