{
  "study": "synthetic MP3 RMS pipeline check",
  "created_date": "2026-09-28",
  "sample": {
    "waveform": "stereo sine wave",
    "frequency_hz": 440,
    "amplitude_peak": 0.5,
    "sample_rate": 48000,
    "duration_seconds": 30,
    "channels": 2,
    "source_rms": 0.3535533898800421
  },
  "conversion": {
    "bitrate_kbps": 192,
    "primary_encoder_family": "Bundled WASM LAME-family path",
    "reference_encoder": "FFmpeg libmp3lame at 192 kbps CBR",
    "no_explicit_gain_or_normalization": true
  },
  "decode_measurement": {
    "method": "FFmpeg float32 decode; RMS over all decoded samples and again after trimming 100 ms from each edge",
    "bundled_wasm": {
      "sample_rate": 48000,
      "channels": 2,
      "duration_seconds": 30.024,
      "full_file_rms_ratio": 0.9696586462411719,
      "central_rms_ratio": 0.9700457873957513
    },
    "ffmpeg_libmp3lame": {
      "sample_rate": 48000,
      "channels": 2,
      "duration_seconds": 30,
      "full_file_rms_ratio": 0.9700600883714159,
      "central_rms_ratio": 0.9700600548811056
    }
  },
  "interpretation": "A similar central RMS ratio in the bundled WASM encoder and FFmpeg's libmp3lame reference indicates that the approximately 3 percent reduction is reproducible on known PCM through the LAME-family encode/decode path. The check does not identify the codec's internal mechanism and does not establish a general property of MP3 encoders."
}