Add script for removing metronome from a recording

demetronome.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+
+import sys
+import wave
+
+# Remove the metronome from a recording.
+#
+# This could be a lot smarter: the beats are a consistent number of samples
+# apart, for example, and we could detect them by looking for samples that are
+# way apart from their neighbors instead of just ones that are very high.  But
+# this works on the sample, so no need to do any more for now.
+
+input_fname, output_fname, threshold = sys.argv[1:]
+threshold = int(threshold)  # try 13000 or so
+
+input_wave = wave.open(input_fname, mode='rb')
+output_wave = wave.open(output_fname, mode='wb')
+
+CHANNELS=1
+WIDTH=2
+
+assert input_wave.getnchannels() == CHANNELS
+assert input_wave.getsampwidth() == WIDTH
+output_wave.setnchannels(input_wave.getnchannels())
+output_wave.setsampwidth(input_wave.getsampwidth())
+output_wave.setframerate(input_wave.getframerate())
+
+l = 0
+samples = []
+while f := input_wave.readframes(1024):
+    l += len(f)
+    prev = None
+    for i, s in enumerate(f):
+        if i % 2 == 0:
+            prev = s
+        else:
+            sample = int.from_bytes([prev, s],
+                                    byteorder="little",
+                                    signed=True)
+            samples.append(sample)
+
+metronome_values = []
+for sample in samples:
+    if sample > threshold:
+        metronome_values.append(sample)
+metronome_average = round(sum(metronome_values) / len(metronome_values))
+
+new_samples = []
+for sample in samples:
+    if sample > threshold:
+        sample -= metronome_average
+    new_samples.append(sample)
+
+new_frames = []
+for sample in new_samples:
+    new_frames.extend(sample.to_bytes(byteorder="little",
+                                      signed=True,
+                                      length=WIDTH))
+
+output_wave.writeframes(bytes(new_frames))