Add program reference suppression and mapping

tests/test_program_reference.py

@@ -0,0 +1,36 @@
+import unittest
+
+import numpy as np
+
+from audio_field.program_reference import suppress_program_reference
+
+
+class ProgramReferenceTests(unittest.TestCase):
+    def test_reference_bleed_is_suppressed_from_channel(self):
+        sample_rate = 48000
+        t = np.arange(sample_rate, dtype=np.float32) / sample_rate
+        reference = 0.2 * np.sin(2 * np.pi * 440 * t) + 0.1 * np.sin(2 * np.pi * 1400 * t)
+        voice = 0.03 * np.sin(2 * np.pi * 220 * t)
+        field = np.zeros((sample_rate, 2), dtype=np.float32)
+        field[:, 0] = voice + 0.7 * reference
+        field[:, 1] = voice
+
+        cleaned, reports = suppress_program_reference(
+            field,
+            reference,
+            sample_rate,
+            channels=[0],
+            nperseg=2048,
+            noverlap=1536,
+            subtraction_strength=1.0,
+        )
+
+        self.assertEqual((sample_rate, 2), cleaned.shape)
+        self.assertLess(reports[0].output_rms, reports[0].input_rms)
+        self.assertLess(float(np.sqrt(np.mean((cleaned[:, 0] - voice) ** 2))), 0.01)
+        np.testing.assert_allclose(cleaned[:, 1], field[:, 1])
+        self.assertGreater(len(reports[0].phase_mapping), 0)
+
+
+if __name__ == "__main__":
+    unittest.main()