{
  "version": "1.56.0",
  "observedAt": "2026-10-14T04:12:41.558Z",
  "scope": "Bounded native desktop Chrome software acceptance on authored synthetic fixtures. All preview monitoring off. This is a soundtrack-content check, not physical latency, a visual-response measurement, or certification for every encoder/browser/device.",
  "method": "Compare shared streaming selection PCM with the same-rate native OfflineAudioContext decode at file start, nonzero cut and file end. Separately save actual browser downloads, decode complete films with FFmpeg, then compare the entire selected content interval at 48 kHz. Container duration and decoded codec tail are recorded separately; matching endpoint metadata alone is insufficient.",
  "sourceFixtureSha256": "aa8d4dafd54fe18a9ad4f0948450f77f4bbfd18b3d4e6d45fc565a74f1299a28",
  "decoderCases": [
    {
      "profile": "CBR MP3 stereo 48 kHz",
      "sampleRate": 48000,
      "timeline": "gapless",
      "contentDuration": 24,
      "nativeDuration": 24,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 3,
          "end": 5,
          "frames": 96000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 23,
          "end": 24,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        }
      ]
    },
    {
      "profile": "PCM WAV stereo 48 kHz",
      "sampleRate": 48000,
      "timeline": "pcm",
      "contentDuration": 24,
      "nativeDuration": 24,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 48000,
          "correlation": 0.9999999998835694,
          "maxError": 0.000026702880859375
        },
        {
          "start": 3,
          "end": 5,
          "frames": 96000,
          "correlation": 0.9999999998835682,
          "maxError": 0.00002574920654296875
        },
        {
          "start": 23,
          "end": 24,
          "frames": 48000,
          "correlation": 0.9999999998836019,
          "maxError": 0.000027120113372802734
        }
      ]
    },
    {
      "profile": "VBR MP3 stereo 48 kHz",
      "sampleRate": 48000,
      "timeline": "gapless",
      "contentDuration": 24,
      "nativeDuration": 24,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 3,
          "end": 5,
          "frames": 96000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 23,
          "end": 24,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        }
      ]
    },
    {
      "profile": "CBR MP3 stereo 44.1 kHz",
      "sampleRate": 44100,
      "timeline": "gapless",
      "contentDuration": 24,
      "nativeDuration": 24,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 44100,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 3,
          "end": 5,
          "frames": 88200,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 23,
          "end": 24,
          "frames": 44100,
          "correlation": 1,
          "maxError": 0
        }
      ]
    },
    {
      "profile": "MP3 without Xing/Info 48 kHz",
      "sampleRate": 48000,
      "timeline": "encoded",
      "contentDuration": 24.024,
      "nativeDuration": 24.024,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 3,
          "end": 5,
          "frames": 96000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 23.024,
          "end": 24.024,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        }
      ]
    },
    {
      "profile": "MPEG2 MP3 mono 24 kHz",
      "sampleRate": 24000,
      "timeline": "gapless",
      "contentDuration": 24,
      "nativeDuration": 24,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 24000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 3,
          "end": 5,
          "frames": 48000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 23,
          "end": 24,
          "frames": 24000,
          "correlation": 1,
          "maxError": 0
        }
      ]
    },
    {
      "profile": "MPEG2.5 MP3 mono 12 kHz",
      "sampleRate": 12000,
      "timeline": "gapless",
      "contentDuration": 24,
      "nativeDuration": 24,
      "windows": [
        {
          "start": 0,
          "end": 1,
          "frames": 12000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 3,
          "end": 5,
          "frames": 24000,
          "correlation": 1,
          "maxError": 0
        },
        {
          "start": 23,
          "end": 24,
          "frames": 12000,
          "correlation": 1,
          "maxError": 0
        }
      ]
    }
  ],
  "reopenedFilms": [
    {
      "input": "MP3",
      "start": 3,
      "duration": 2,
      "decodedContentSamples": 96000,
      "decodedTailSamples": 648,
      "sampleRate": 48000,
      "alignmentSamples": 0,
      "correlation": 0.9989106969069521,
      "gain": 0.7497921459412087,
      "containerDuration": 2.02,
      "dimensions": [
        540,
        540
      ],
      "codecs": [
        "VP9",
        "Opus"
      ],
      "bytes": 1919451,
      "sha256": "2b3a11e66b89c18d50f987e4b3ac42a966a5f70968925a6bff8ac887c3412da9"
    },
    {
      "input": "WAV",
      "start": 23,
      "duration": 1,
      "decodedContentSamples": 48000,
      "decodedTailSamples": 648,
      "sampleRate": 48000,
      "alignmentSamples": 0,
      "correlation": 0.9984323908695858,
      "gain": 0.7471342220302132,
      "containerDuration": 1.02,
      "dimensions": [
        540,
        540
      ],
      "codecs": [
        "VP9",
        "Opus"
      ],
      "bytes": 985763,
      "sha256": "f02b4169f22bc49b050be33a430e3fe072abacb822e4d3f9d9742f63d7ff776b"
    }
  ],
  "limits": "Only internally consistent, checksum-verified known gapless metadata is normalized. Unknown metadata keeps encoded time. No untagged fixed correction or universal sample-accurate A/V claim. Current public instructions: /guides/youtube-visualizer/#file-render."
}