Cross-correlates left/right ear audio frames (512 samples, ~32ms window)
to find the sub-millisecond delay between arrays. Converts delay to
bearing angle using speed of sound and array separation.
At 16kHz with 175mm separation, resolution is ~1 sample = 62.5μs = ~7°.
Not lab-grade, but adds a third independent angle estimate alongside
DoA and ILD. Works with current 2-channel firmware — no raw mics needed.
New fields in /doa spatial response:
itd_angle: bearing from cross-correlation (degrees)
itd_delay_us: raw time delay (microseconds, positive = source on right)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Computes Interaural Level Difference (dB) from left/right ear energy.
Fuses with triangulated distance (70/30 weight) for more robust estimate.
Classifies into proximity zones: intimate (<0.5m), conversational (0.5-2m),
across_room (2-5m), far (>5m).
ILD→distance mapping is empirical and should be calibrated per install.
Gaze vertical component now responds to proximity (closer = eyes down).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
binaural_recorder.py: Records left/right ear streams as stereo WAV
in rolling 5-minute segments. Training data for spatial audio models.
Enabled via BINAURAL_RECORD=1 env var.
spatial.py: Tune smoothing — alpha 0.3→0.4 (snappier response),
idle return speed 0.05→0.03 (gentler drift), timeout 2s→1.5s.
headmic.py: Wire binaural recorder into audio loop, add /recording
endpoint for stats, feed both ear streams (not just best beam).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
spatial.py: Triangulates sound source position from two DoA angles using
ray intersection. Exponential smoothing prevents jitter. Gaze drifts back
to center after 2s of silence. Converts position (mm) to gaze (0-255).
headmic.py: Replaces simple doa_poll_loop with doa_track_loop that runs
the spatial tracker and pushes gaze to the eye service when the position
changes. Rate-limited to 10 pushes/sec with minimum delta threshold.
/doa endpoint now returns triangulated position + gaze coordinates.
Array separation (175mm) stored in config, overridable.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
