From e3f4efe93e5d84e2dfbf99d9e8e72380c4955e29 Mon Sep 17 00:00:00 2001
From: Chris Frankland-Wright <christopherjfrankland@googlemail.com>
Date: Tue, 24 Jun 2025 20:16:25 +0100
Subject: [PATCH] ltc probe

---
 ltc_probe.py | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 ltc_probe.py

diff --git a/ltc_probe.py b/ltc_probe.py
new file mode 100644
index 0000000..4b63d37
--- /dev/null
+++ b/ltc_probe.py
@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+
+"""
+ltc_probe.py
+Probes audio input to detect LTC-like signal characteristics.
+Reports zero crossings and estimated frequency.
+"""
+
+import numpy as np
+import sounddevice as sd
+
+DURATION = 1.0  # seconds
+SAMPLERATE = 48000
+CHANNELS = 1
+EXPECTED_FREQ = 2000  # Approx LTC edge rate at 25fps
+
+def count_zero_crossings(signal):
+    signal = signal.flatten()
+    signs = np.sign(signal)
+    return np.count_nonzero(np.diff(signs))
+
+def verdict(freq):
+    if freq < 100:
+        return "❌ No signal detected (flatline or silence)"
+    elif 1800 <= freq <= 2200:
+        return f"✅ LTC-like signal detected (freq: {freq:.1f} Hz)"
+    else:
+        return f"⚠️ Unstable or non-LTC signal (freq: {freq:.1f} Hz)"
+
+def main():
+    print("🔍 Capturing 1 second of audio for LTC probing...")
+    audio = sd.rec(int(DURATION * SAMPLERATE), samplerate=SAMPLERATE, channels=CHANNELS, dtype='float32')
+    sd.wait()
+
+    crossings = count_zero_crossings(audio)
+    estimated_freq = crossings / DURATION
+
+    print(f"Zero crossings: {crossings}")
+    print(f"Estimated frequency: {estimated_freq:.1f} Hz")
+    print(verdict(estimated_freq))
+
+if __name__ == "__main__":
+    main()