{
  "experiment_date": "2026-10-20",
  "library": "Mediabunny1.52.0",
  "environment": {
    "cpu": "Apple M4",
    "ram_gib": 32,
    "os": "macOS27.0.1",
    "browser": "Chrome155.0.8059.85 headless",
    "ffmpeg": "9.0.1"
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    "height": 1080,
    "fps": 30,
    "frames": 600,
    "seconds": 20,
    "video": "libx264 CRF16,maxrate8M,bufsize8M,noBframes,yuv420p",
    "audio": "AAC-LC48kHzmono,128kbps requested"
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        "text_ssim": 0.995649,
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        "full_psnr": 27.66874,
        "text_ssim": 0.99702,
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      "audio_encode_calls": [
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      "audio_payload_preserved": [
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      "audio_end_delta_ms": 0,
      "video_end_delta_ms": -21.353999999998763,
      "audio_packet_counts": [
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      "video_packet_hashes": [
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    {
      "id": "normalized-force",
      "completed": 2,
      "bytes": [
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      "times_ms": [
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      "median_ms": 3937.2999999523163,
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      "quality": {
        "full_ssim": 0.983413,
        "full_psnr": 27.66874,
        "text_ssim": 0.99702,
        "text_psnr": 44.000487
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      "absolute_av_offset_ms": [
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      "added_av_offset_ms": [
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      "audio_encode_calls": [
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      ],
      "audio_payload_preserved": [
        false,
        false
      ],
      "audio_end_delta_ms": 74.66599999999701,
      "video_end_delta_ms": -21.353999999998763,
      "audio_packet_counts": [
        942,
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      ],
      "video_packet_hashes": [
        "12005964093543c6c18fe346dbf32d7a8782b532892e56b447b1284badfdde91",
        "12005964093543c6c18fe346dbf32d7a8782b532892e56b447b1284badfdde91"
      ]
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  ],
  "timing_scope": "Conversion.init through execute completion; excludesinput loading,JS loading,transfer,saving,analysis",
  "quality_scope": "Full600decoded frames and1120x320textROI versus decoded lossy reference; same encoded video payload hash permits explicit metric reuse",
  "audio_detector": "5msnonoverlapping RMS windows,threshold0.1;flashROI gray>200;actualframePTS",
  "causal_comparison": {
    "same_normalized_input_sha256": "17160b06edf59ae34fc2c49b8fad65e4138324c67ed023141c54b0179015aa93",
    "video_payloads_identical_in_all4normalized_trials": true,
    "all600actual_video_frame_pts_identical_in_new3trials": true,
    "toggle": "audio:{} vs audio:{forceTranscode:true}",
    "default_audio_calls": 0,
    "forced_audio_calls": 939,
    "default_absolute_offset_ms_approx": 20,
    "forced_absolute_offset_ms_approx": 65,
    "forced_minus_default_ms_approx": 45,
    "repetitions_each": 2,
    "audio_detector_resolution_ms": 5,
    "causality_scope": "On this same normalized synthetic input/browser, selecting forced audio reencode adds about45ms relative to passthrough. Exact delay allocation among library/browser/AAC internals is not isolated.",
    "frame_timing_contribution_ms_approx": 21.354,
    "q32_with_normalized_input_not_tested": true
  },
  "limits": [
    "One synthetic20sinput,oneMac/browser;3repeats perquantizer and2peraudio condition.",
    "Visual review byAI on selectedframes60and450,not blinded human/OCR accuracy.",
    "Do not generalize approximately45msaudio-path difference beyond this environment.",
    "q32withnormalized input not tested."
  ],
  "analysis_correction": "Normalized input firstframe duration54.688ms invalidated frame_index/30. Corrected using actual decoded framePTS of byte-identical remux; originalinput settings metrics unchanged."
}