initial commit and version 1.0

moviepy/audio/fx/AudioFadeOut.py

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+from dataclasses import dataclass
+
+import numpy as np
+
+from moviepy.Clip import Clip
+from moviepy.decorators import audio_video_effect
+from moviepy.Effect import Effect
+from moviepy.tools import convert_to_seconds
+
+
+@dataclass
+class AudioFadeOut(Effect):
+    """Return a sound clip where the sound fades out progressively
+    over ``duration`` seconds at the end of the clip.
+
+    Parameters
+    ----------
+
+    duration : float
+      How long does it take for the sound to reach the zero level at the end
+      of the clip.
+
+    Examples
+    --------
+
+    .. code:: python
+
+        clip = VideoFileClip("media/chaplin.mp4")
+        clip.with_effects([afx.AudioFadeOut("00:00:06")])
+    """
+
+    duration: float
+
+    def __post_init__(self):
+        self.duration = convert_to_seconds(self.duration)
+
+    def _mono_factor_getter(self, clip_duration):
+        return lambda t, duration: np.minimum(1.0 * (clip_duration - t) / duration, 1)
+
+    def _stereo_factor_getter(self, clip_duration, nchannels):
+        def getter(t, duration):
+            factor = np.minimum(1.0 * (clip_duration - t) / duration, 1)
+            return np.array([factor for _ in range(nchannels)]).T
+
+        return getter
+
+    @audio_video_effect
+    def apply(self, clip: Clip) -> Clip:
+        """Apply the effect to the clip."""
+        if clip.duration is None:
+            raise ValueError("Attribute 'duration' not set")
+
+        get_factor = (
+            self._mono_factor_getter(clip.duration)
+            if clip.nchannels == 1
+            else self._stereo_factor_getter(clip.duration, clip.nchannels)
+        )
+
+        return clip.transform(
+            lambda get_frame, t: get_factor(t, self.duration) * get_frame(t),
+            keep_duration=True,
+        )