this makes more sense

bin/mtag/README.md

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+standalone programs which take an audio file as argument
+
+some of these rely on libraries which are not MIT-compatible
+
+* [audio-bpm.py](./audio-bpm.py) detects the BPM of music using the BeatRoot Vamp Plugin; imports GPL2
+* [audio-key.py](./audio-key.py) detects the melodic key of music using the Mixxx fork of keyfinder; imports GPL3

bin/mtag/audio-bpm.py

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+#!/usr/bin/env python
+
+import os
+import sys
+import vamp
+import tempfile
+import numpy as np
+import subprocess as sp
+
+from copyparty.util import fsenc
+
+"""
+dep: vamp
+dep: beatroot-vamp
+dep: ffmpeg
+"""
+
+
+def det(tf):
+    # fmt: off
+    sp.check_call([
+        "ffmpeg",
+        "-nostdin",
+        "-hide_banner",
+        "-v", "fatal",
+        "-ss", "13",
+        "-y", "-i", fsenc(sys.argv[1]),
+        "-ac", "1",
+        "-ar", "22050",
+        "-t", "300",
+        "-f", "f32le",
+        tf
+    ])
+    # fmt: on
+
+    with open(tf, "rb") as f:
+        d = np.fromfile(f, dtype=np.float32)
+        c = vamp.collect(d, 22050, "beatroot-vamp:beatroot")
+        cl = c["list"]
+
+        # throws if detection failed:
+        bpm = float(cl[-1]["timestamp"] - cl[1]["timestamp"])
+        bpm = round(60 * ((len(cl) - 1) / bpm), 2)
+        print(f"{bpm:.2f}")
+
+
+def main():
+    with tempfile.NamedTemporaryFile(suffix=".pcm", delete=False) as f:
+        f.write(b"h")
+        tf = f.name
+
+    try:
+        det(tf)
+    except:
+        pass
+    finally:
+        os.unlink(tf)
+
+
+if __name__ == "__main__":
+    main()

bin/mtag/audio-key.py

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+#!/usr/bin/env python
+
+import sys
+import keyfinder
+
+"""
+dep: github/mixxxdj/libkeyfinder
+dep: pypi/keyfinder
+dep: ffmpeg
+
+note: cannot fsenc
+"""
+
+
+try:
+    print(keyfinder.key(sys.argv[1]).camelot())
+except:
+    pass