Mimir

Realtime cameras, microphones, chirplets, and field evidence organized into one coherent stream machine.

Calibration Session Spec

3 min read

Calibration Session Spec

Purpose

The calibration command should be the machine that turns a real room into a path model. It should not be a pile of one-off artifact commands that only the current operator remembers how to arrange.

Objective

Emit a known active witness, capture loopback and every microphone in the same clock domain where possible, compute per-output/mic response/confusion/delay models, persist them, and immediately prove that the live decoder improves when those models are loaded.

Inputs

  • output path id;
  • ASIO driver id / source manifest;
  • sample rate;
  • duration;
  • emission mode (chirp-only, hybrid-watermark, silent-passive-baseline);
  • candidate symbol plan;
  • mic geometry file if available;
  • artifact directory.

Outputs

  • raw capture artifact;
  • rendered witness artifact;
  • manifest with device/channel/sample-rate/buffer-size/gain notes;
  • MimirChirpBinCalibrationModel;
  • per-path usable-band table;
  • confusion matrix;
  • timing residual table;
  • group-delay estimate;
  • recommended codebook plan;
  • before/after decode report.

Command Shape

Future production command:

dotnet run --project .\src\Mimir.BufferSmoke\Mimir.BufferSmoke.csproj -- `
  --calibration-session `
  --config .\config\mimir-runtime.asio.json `
  --output-path scarlett-main-out `
  --seconds 30 `
  --sample-rate 192000 `
  --artifact-dir .\calibration\runs\2026-05-24-starfire

This can start as BufferSmoke, but the final owner should be a runtime command or app action that uses the same ASIO/native path as production.

Session Phases

1. Preflight

  • enumerate ASIO inputs/outputs;
  • verify requested sample rate and buffer size;
  • verify loopback channels are present;
  • verify input channels are non-silent when expected;
  • record channel names and source ids;
  • load existing calibration for comparison.

Fail fast if loopback is absent. Without loopback, the session can still record diagnostics, but it cannot become canonical calibration.

2. Passive Baseline

Capture room/program audio without active witness for a short window.

Purpose:

  • noise floor;
  • current music/program spectrum;
  • passive correlation strength;
  • mic gain sanity.

3. Active Emission

Render a deterministic chirp-bin/watermark witness using the candidate symbol plan. Capture loopback and all inputs.

Important:

  • event ids and schedule seed go into the manifest;
  • emitted codebook plan goes into the artifact;
  • output gain should be recorded manually or through driver state if possible.

4. Decode And Score

For each input:

  • decode loopback anchors;
  • decode mic anchors;
  • compute matched anchor delays;
  • compute expected-symbol versus observed-bin matrix;
  • compute timing residuals;
  • estimate magnitude response;
  • estimate phase/group delay where phase evidence is stable;
  • generate delay/bin-shift hypotheses.

5. Plan Adaptation

Across all selected mics:

  • identify reliable bins;
  • identify dead/aliased bins;
  • choose reduced alphabet;
  • choose higher de Bruijn order if necessary;
  • estimate expected time-to-unique-lock;
  • write recommended emission plan.

6. Replay Proof

Reload the persisted model and decode the same artifact:

  • unweighted decode report;
  • weighted/adapted decode report;
  • anchor gain/loss;
  • confidence gain/loss;
  • delay residual gain/loss.

If the calibrated model does not improve the capture, the command should say so plainly. A calibration file that cannot improve the decoder is just decorative paperwork with a badge.

Persisted Model Shape

Minimum:

{
  "schema": "gamecult.mimir.chirp_bin_calibration.v1",
  "createdUtc": "2026-05-24T00:00:00Z",
  "sampleRate": 192000,
  "outputPathId": "scarlett-main-out",
  "emissionPlan": {},
  "paths": [
    {
      "sourceId": "asio-ch0",
      "usableBands": [],
      "symbols": [],
      "delayHypotheses": [],
      "phaseModel": {},
      "groupDelayModel": {},
      "confidence": 0.0
    }
  ]
}

Acceptance Criteria

  • loopback decodes confidently;
  • at least one physical mic produces code-valid anchors;
  • calibration identifies reliable and unreliable bands;
  • adapted emission plan changes the symbol set when the original bands are bad;
  • loaded calibration affects likelihood before codebook solving;
  • replay proof is stored with the model.

Failure Records

A failed calibration is still useful if it records:

  • no loopback;
  • silent mic;
  • clipping;
  • insufficient high-frequency response;
  • strong alias/confusion;
  • group delay too unstable;
  • active witness too quiet/loud;
  • room reflection dominated direct path.

Do not delete failed runs unless they are accidental trash. They are evidence.

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