initial commit and version 1.0

moviepy/audio/fx/MultiplyVolume.py

@@ -0,0 +1,90 @@
+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 MultiplyVolume(Effect):
+    """Returns a clip with audio volume multiplied by the
+    value `factor`. Can be applied to both audio and video clips.
+
+    Parameters
+    ----------
+
+    factor : float
+      Volume multiplication factor.
+
+    start_time : float, optional
+      Time from the beginning of the clip until the volume transformation
+      begins to take effect, in seconds. By default at the beginning.
+
+    end_time : float, optional
+      Time from the beginning of the clip until the volume transformation
+      ends to take effect, in seconds. By default at the end.
+
+    Examples
+    --------
+
+    .. code:: python
+
+        from moviepy import AudioFileClip
+
+        music = AudioFileClip("music.ogg")
+        # doubles audio volume
+        doubled_audio_clip = music.with_effects([afx.MultiplyVolume(2)])
+        # halves audio volume
+        half_audio_clip = music.with_effects([afx.MultiplyVolume(0.5)])
+        # silences clip during one second at third
+        effect = afx.MultiplyVolume(0, start_time=2, end_time=3)
+        silenced_clip = clip.with_effects([effect])
+    """
+
+    factor: float
+    start_time: float = None
+    end_time: float = None
+
+    def __post_init__(self):
+        if self.start_time is not None:
+            self.start_time = convert_to_seconds(self.start_time)
+
+        if self.end_time is not None:
+            self.end_time = convert_to_seconds(self.end_time)
+
+    def _multiply_volume_in_range(self, factor, start_time, end_time, nchannels):
+        def factors_filter(factor, t):
+            return np.array([factor if start_time <= t_ <= end_time else 1 for t_ in t])
+
+        def multiply_stereo_volume(get_frame, t):
+            return np.multiply(
+                get_frame(t),
+                np.array([factors_filter(factor, t) for _ in range(nchannels)]).T,
+            )
+
+        def multiply_mono_volume(get_frame, t):
+            return np.multiply(get_frame(t), factors_filter(factor, t))
+
+        return multiply_mono_volume if nchannels == 1 else multiply_stereo_volume
+
+    @audio_video_effect
+    def apply(self, clip: Clip) -> Clip:
+        """Apply the effect to the clip."""
+        if self.start_time is None and self.end_time is None:
+            return clip.transform(
+                lambda get_frame, t: self.factor * get_frame(t),
+                keep_duration=True,
+            )
+
+        return clip.transform(
+            self._multiply_volume_in_range(
+                self.factor,
+                clip.start if self.start_time is None else self.start_time,
+                clip.end if self.end_time is None else self.end_time,
+                clip.nchannels,
+            ),
+            keep_duration=True,
+        )