Refactor: separate adjust_voice() function from tts_model.py

style_bert_vits2/voice.py

@@ -0,0 +1,46 @@
+from typing import Any
+
+import numpy as np
+from numpy.typing import NDArray
+
+
+def adjust_voice(
+    fs: int,
+    wave: NDArray[Any],
+    pitch_scale: float = 1.0,
+    intonation_scale: float = 1.0,
+) -> tuple[int, NDArray[Any]]:
+
+    if pitch_scale == 1.0 and intonation_scale == 1.0:
+        # 初期値の場合は、音質劣化を避けるためにそのまま返す
+        return fs, wave
+
+    try:
+        import pyworld
+    except ImportError:
+        raise ImportError(
+            "pyworld is not installed. Please install it by `pip install pyworld`"
+        )
+
+    # pyworld で f0 を加工して合成
+    # pyworld よりもよいのがあるかもしれないが……
+    ## pyworld は Cython で書かれているが、スタブファイルがないため型補完が全く効かない…
+
+    wave = wave.astype(np.double)
+
+    # 質が高そうだしとりあえずharvestにしておく
+    f0, t = pyworld.harvest(wave, fs)  # type: ignore
+
+    sp = pyworld.cheaptrick(wave, f0, t, fs)  # type: ignore
+    ap = pyworld.d4c(wave, f0, t, fs)  # type: ignore
+
+    non_zero_f0 = [f for f in f0 if f != 0]
+    f0_mean = sum(non_zero_f0) / len(non_zero_f0)
+
+    for i, f in enumerate(f0):
+        if f == 0:
+            continue
+        f0[i] = pitch_scale * f0_mean + intonation_scale * (f - f0_mean)
+
+    wave = pyworld.synthesize(f0, sp, ap, fs)  # type: ignore
+    return fs, wave