176 lines
6.5 KiB
Python
176 lines
6.5 KiB
Python
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"""
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This module provides scipy versions of high_pass_filter, and low_pass_filter
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as well as an additional band_pass_filter.
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Of course, you will need to install scipy for these to work.
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When this module is imported the high and low pass filters from this module
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will be used when calling audio_segment.high_pass_filter() and
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audio_segment.high_pass_filter() instead of the slower, less powerful versions
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provided by pydub.effects.
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"""
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from scipy.signal import butter, sosfilt
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from .utils import (register_pydub_effect,stereo_to_ms,ms_to_stereo)
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def _mk_butter_filter(freq, type, order):
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"""
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Args:
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freq: The cutoff frequency for highpass and lowpass filters. For
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band filters, a list of [low_cutoff, high_cutoff]
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type: "lowpass", "highpass", or "band"
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order: nth order butterworth filter (default: 5th order). The
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attenuation is -6dB/octave beyond the cutoff frequency (for 1st
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order). A Higher order filter will have more attenuation, each level
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adding an additional -6dB (so a 3rd order butterworth filter would
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be -18dB/octave).
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Returns:
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function which can filter a mono audio segment
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"""
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def filter_fn(seg):
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assert seg.channels == 1
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nyq = 0.5 * seg.frame_rate
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try:
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freqs = [f / nyq for f in freq]
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except TypeError:
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freqs = freq / nyq
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sos = butter(order, freqs, btype=type, output='sos')
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y = sosfilt(sos, seg.get_array_of_samples())
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return seg._spawn(y.astype(seg.array_type))
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return filter_fn
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@register_pydub_effect
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def band_pass_filter(seg, low_cutoff_freq, high_cutoff_freq, order=5):
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filter_fn = _mk_butter_filter([low_cutoff_freq, high_cutoff_freq], 'band', order=order)
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return seg.apply_mono_filter_to_each_channel(filter_fn)
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@register_pydub_effect
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def high_pass_filter(seg, cutoff_freq, order=5):
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filter_fn = _mk_butter_filter(cutoff_freq, 'highpass', order=order)
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return seg.apply_mono_filter_to_each_channel(filter_fn)
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@register_pydub_effect
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def low_pass_filter(seg, cutoff_freq, order=5):
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filter_fn = _mk_butter_filter(cutoff_freq, 'lowpass', order=order)
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return seg.apply_mono_filter_to_each_channel(filter_fn)
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@register_pydub_effect
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def _eq(seg, focus_freq, bandwidth=100, mode="peak", gain_dB=0, order=2):
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"""
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Args:
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focus_freq - middle frequency or known frequency of band (in Hz)
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bandwidth - range of the equalizer band
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mode - Mode of Equalization(Peak/Notch(Bell Curve),High Shelf, Low Shelf)
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order - Rolloff factor(1 - 6dB/Octave 2 - 12dB/Octave)
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Returns:
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Equalized/Filtered AudioSegment
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"""
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filt_mode = ["peak", "low_shelf", "high_shelf"]
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if mode not in filt_mode:
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raise ValueError("Incorrect Mode Selection")
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if gain_dB >= 0:
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if mode == "peak":
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sec = band_pass_filter(seg, focus_freq - bandwidth/2, focus_freq + bandwidth/2, order = order)
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seg = seg.overlay(sec - (3 - gain_dB))
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return seg
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if mode == "low_shelf":
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sec = low_pass_filter(seg, focus_freq, order=order)
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seg = seg.overlay(sec - (3 - gain_dB))
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return seg
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if mode == "high_shelf":
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sec = high_pass_filter(seg, focus_freq, order=order)
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seg = seg.overlay(sec - (3 - gain_dB))
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return seg
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if gain_dB < 0:
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if mode == "peak":
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sec = high_pass_filter(seg, focus_freq - bandwidth/2, order=order)
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seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
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sec = low_pass_filter(seg, focus_freq + bandwidth/2, order=order)
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seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
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return seg
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if mode == "low_shelf":
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sec = high_pass_filter(seg, focus_freq, order=order)
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seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
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return seg
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if mode=="high_shelf":
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sec=low_pass_filter(seg, focus_freq, order=order)
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seg=seg.overlay(sec - (3 + gain_dB)) +gain_dB
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return seg
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@register_pydub_effect
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def eq(seg, focus_freq, bandwidth=100, channel_mode="L+R", filter_mode="peak", gain_dB=0, order=2):
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"""
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Args:
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focus_freq - middle frequency or known frequency of band (in Hz)
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bandwidth - range of the equalizer band
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channel_mode - Select Channels to be affected by the filter.
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L+R - Standard Stereo Filter
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L - Only Left Channel is Filtered
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R - Only Right Channel is Filtered
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M+S - Blumlien Stereo Filter(Mid-Side)
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M - Only Mid Channel is Filtered
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S - Only Side Channel is Filtered
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Mono Audio Segments are completely filtered.
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filter_mode - Mode of Equalization(Peak/Notch(Bell Curve),High Shelf, Low Shelf)
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order - Rolloff factor(1 - 6dB/Octave 2 - 12dB/Octave)
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Returns:
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Equalized/Filtered AudioSegment
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"""
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channel_modes = ["L+R", "M+S", "L", "R", "M", "S"]
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if channel_mode not in channel_modes:
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raise ValueError("Incorrect Channel Mode Selection")
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if seg.channels == 1:
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return _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
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if channel_mode == "L+R":
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return _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
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if channel_mode == "L":
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seg = seg.split_to_mono()
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seg = [_eq(seg[0], focus_freq, bandwidth, filter_mode, gain_dB, order), seg[1]]
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return AudioSegment.from_mono_audio_segements(seg[0], seg[1])
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if channel_mode == "R":
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seg = seg.split_to_mono()
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seg = [seg[0], _eq(seg[1], focus_freq, bandwidth, filter_mode, gain_dB, order)]
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return AudioSegment.from_mono_audio_segements(seg[0], seg[1])
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if channel_mode == "M+S":
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seg = stereo_to_ms(seg)
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seg = _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
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return ms_to_stereo(seg)
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if channel_mode == "M":
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seg = stereo_to_ms(seg).split_to_mono()
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seg = [_eq(seg[0], focus_freq, bandwidth, filter_mode, gain_dB, order), seg[1]]
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seg = AudioSegment.from_mono_audio_segements(seg[0], seg[1])
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return ms_to_stereo(seg)
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if channel_mode == "S":
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seg = stereo_to_ms(seg).split_to_mono()
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seg = [seg[0], _eq(seg[1], focus_freq, bandwidth, filter_mode, gain_dB, order)]
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seg = AudioSegment.from_mono_audio_segements(seg[0], seg[1])
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return ms_to_stereo(seg)
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