D1: LUFS EBU R128 + true peak sau render (app/core/loudness.py), API /plugins/render tra them lufs/true_peak_db, test 4 cases

tests/test_loudness.py

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+"""D1: EBU R128 loudness + true peak metrics (app/core/loudness.py)."""
+import numpy as np
+
+from app.core import loudness
+
+
+def _sine(dbfs, sr=44100, sec=3.0, freq=1000.0):
+    t = np.arange(int(sr * sec)) / sr
+    x = (10 ** (dbfs / 20.0)) * np.sin(2 * np.pi * freq * t)
+    return np.stack([x, x])
+
+
+def test_sine_minus20_lufs():
+    # 1 kHz sine @ -20 dBFS: RMS -23.01 dB + K-weight +0.44 dB - 0.691 offset
+    # => ~ -23.3 LUFS (0 dBFS sine ~ -3.7 LUFS per EBU R128).
+    audio = _sine(-20.0)
+    lufs = loudness.integrated_lufs(audio, 44100)
+    assert -24.5 < lufs < -22.0, lufs
+    tp = loudness.true_peak_db(audio, 44100)
+    assert abs(tp - (-20.0)) < 0.2, tp
+
+
+def test_true_peak_inter_sample_overshoot():
+    # Square-ish: sample peak 0 dBFS, oversampled true peak > 0 dBTP.
+    sr = 44100
+    x = np.repeat([1.0, 1.0, -1.0, -1.0], int(sr * 0.125))
+    audio = np.stack([x, x])
+    assert loudness.true_peak_db(audio, sr) > 0.05
+
+
+def test_silence_inf():
+    audio = np.zeros((2, 44100))
+    assert loudness.integrated_lufs(audio, 44100) == -np.inf
+    assert loudness.true_peak_db(audio, 44100) == -np.inf
+
+
+def test_mono_and_stereo_same():
+    sr = 44100
+    t = np.arange(sr * 2) / sr
+    x = 0.2 * np.sin(2 * np.pi * 440 * t)
+    mono = loudness.integrated_lufs(x, sr)
+    stereo = loudness.integrated_lufs(np.stack([x, x]), sr)
+    assert abs(mono - stereo) < 1e-6