File size: 9,195 Bytes
4de32eb
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
import numpy as np


# This function is obtained from librosa.
def get_rms(

    y,

    frame_length=2048,

    hop_length=512,

    pad_mode="constant",

):
    padding = (int(frame_length // 2), int(frame_length // 2))
    y = np.pad(y, padding, mode=pad_mode)

    axis = -1
    # put our new within-frame axis at the end for now
    out_strides = y.strides + tuple([y.strides[axis]])
    # Reduce the shape on the framing axis
    x_shape_trimmed = list(y.shape)
    x_shape_trimmed[axis] -= frame_length - 1
    out_shape = tuple(x_shape_trimmed) + tuple([frame_length])
    xw = np.lib.stride_tricks.as_strided(y, shape=out_shape, strides=out_strides)
    if axis < 0:
        target_axis = axis - 1
    else:
        target_axis = axis + 1
    xw = np.moveaxis(xw, -1, target_axis)
    # Downsample along the target axis
    slices = [slice(None)] * xw.ndim
    slices[axis] = slice(0, None, hop_length)
    x = xw[tuple(slices)]

    # Calculate power
    power = np.mean(np.abs(x) ** 2, axis=-2, keepdims=True)

    return np.sqrt(power)


class Slicer:
    def __init__(

        self,

        sr: int,

        threshold: float = -40.0,

        min_length: int = 5000,

        min_interval: int = 300,

        hop_size: int = 20,

        max_sil_kept: int = 5000,

    ):
        if not min_length >= min_interval >= hop_size:
            raise ValueError(
                "The following condition must be satisfied: min_length >= min_interval >= hop_size"
            )
        if not max_sil_kept >= hop_size:
            raise ValueError(
                "The following condition must be satisfied: max_sil_kept >= hop_size"
            )
        min_interval = sr * min_interval / 1000
        self.threshold = 10 ** (threshold / 20.0)
        self.hop_size = round(sr * hop_size / 1000)
        self.win_size = min(round(min_interval), 4 * self.hop_size)
        self.min_length = round(sr * min_length / 1000 / self.hop_size)
        self.min_interval = round(min_interval / self.hop_size)
        self.max_sil_kept = round(sr * max_sil_kept / 1000 / self.hop_size)

    def _apply_slice(self, waveform, begin, end):
        if len(waveform.shape) > 1:
            return waveform[
                :, begin * self.hop_size : min(waveform.shape[1], end * self.hop_size)
            ]
        else:
            return waveform[
                begin * self.hop_size : min(waveform.shape[0], end * self.hop_size)
            ]

    # @timeit
    def slice(self, waveform):
        if len(waveform.shape) > 1:
            samples = waveform.mean(axis=0)
        else:
            samples = waveform
        if samples.shape[0] <= self.min_length:
            return [waveform]
        rms_list = get_rms(
            y=samples, frame_length=self.win_size, hop_length=self.hop_size
        ).squeeze(0)
        sil_tags = []
        silence_start = None
        clip_start = 0
        for i, rms in enumerate(rms_list):
            # Keep looping while frame is silent.
            if rms < self.threshold:
                # Record start of silent frames.
                if silence_start is None:
                    silence_start = i
                continue
            # Keep looping while frame is not silent and silence start has not been recorded.
            if silence_start is None:
                continue
            # Clear recorded silence start if interval is not enough or clip is too short
            is_leading_silence = silence_start == 0 and i > self.max_sil_kept
            need_slice_middle = (
                i - silence_start >= self.min_interval
                and i - clip_start >= self.min_length
            )
            if not is_leading_silence and not need_slice_middle:
                silence_start = None
                continue
            # Need slicing. Record the range of silent frames to be removed.
            if i - silence_start <= self.max_sil_kept:
                pos = rms_list[silence_start : i + 1].argmin() + silence_start
                if silence_start == 0:
                    sil_tags.append((0, pos))
                else:
                    sil_tags.append((pos, pos))
                clip_start = pos
            elif i - silence_start <= self.max_sil_kept * 2:
                pos = rms_list[
                    i - self.max_sil_kept : silence_start + self.max_sil_kept + 1
                ].argmin()
                pos += i - self.max_sil_kept
                pos_l = (
                    rms_list[
                        silence_start : silence_start + self.max_sil_kept + 1
                    ].argmin()
                    + silence_start
                )
                pos_r = (
                    rms_list[i - self.max_sil_kept : i + 1].argmin()
                    + i
                    - self.max_sil_kept
                )
                if silence_start == 0:
                    sil_tags.append((0, pos_r))
                    clip_start = pos_r
                else:
                    sil_tags.append((min(pos_l, pos), max(pos_r, pos)))
                    clip_start = max(pos_r, pos)
            else:
                pos_l = (
                    rms_list[
                        silence_start : silence_start + self.max_sil_kept + 1
                    ].argmin()
                    + silence_start
                )
                pos_r = (
                    rms_list[i - self.max_sil_kept : i + 1].argmin()
                    + i
                    - self.max_sil_kept
                )
                if silence_start == 0:
                    sil_tags.append((0, pos_r))
                else:
                    sil_tags.append((pos_l, pos_r))
                clip_start = pos_r
            silence_start = None
        # Deal with trailing silence.
        total_frames = rms_list.shape[0]
        if (
            silence_start is not None
            and total_frames - silence_start >= self.min_interval
        ):
            silence_end = min(total_frames, silence_start + self.max_sil_kept)
            pos = rms_list[silence_start : silence_end + 1].argmin() + silence_start
            sil_tags.append((pos, total_frames + 1))
        # Apply and return slices.
        if len(sil_tags) == 0:
            return [waveform]
        else:
            chunks = []
            if sil_tags[0][0] > 0:
                chunks.append(self._apply_slice(waveform, 0, sil_tags[0][0]))
            for i in range(len(sil_tags) - 1):
                chunks.append(
                    self._apply_slice(waveform, sil_tags[i][1], sil_tags[i + 1][0])
                )
            if sil_tags[-1][1] < total_frames:
                chunks.append(
                    self._apply_slice(waveform, sil_tags[-1][1], total_frames)
                )
            return chunks


def main():
    import os.path
    from argparse import ArgumentParser

    import librosa
    import soundfile

    parser = ArgumentParser()
    parser.add_argument("audio", type=str, help="The audio to be sliced")
    parser.add_argument(
        "--out", type=str, help="Output directory of the sliced audio clips"
    )
    parser.add_argument(
        "--db_thresh",
        type=float,
        required=False,
        default=-40,
        help="The dB threshold for silence detection",
    )
    parser.add_argument(
        "--min_length",
        type=int,
        required=False,
        default=5000,
        help="The minimum milliseconds required for each sliced audio clip",
    )
    parser.add_argument(
        "--min_interval",
        type=int,
        required=False,
        default=300,
        help="The minimum milliseconds for a silence part to be sliced",
    )
    parser.add_argument(
        "--hop_size",
        type=int,
        required=False,
        default=10,
        help="Frame length in milliseconds",
    )
    parser.add_argument(
        "--max_sil_kept",
        type=int,
        required=False,
        default=500,
        help="The maximum silence length kept around the sliced clip, presented in milliseconds",
    )
    args = parser.parse_args()
    out = args.out
    if out is None:
        out = os.path.dirname(os.path.abspath(args.audio))
    audio, sr = librosa.load(args.audio, sr=None, mono=False)
    slicer = Slicer(
        sr=sr,
        threshold=args.db_thresh,
        min_length=args.min_length,
        min_interval=args.min_interval,
        hop_size=args.hop_size,
        max_sil_kept=args.max_sil_kept,
    )
    chunks = slicer.slice(audio)
    if not os.path.exists(out):
        os.makedirs(out)
    for i, chunk in enumerate(chunks):
        if len(chunk.shape) > 1:
            chunk = chunk.T
        soundfile.write(
            os.path.join(
                out,
                f"%s_%d.wav"
                % (os.path.basename(args.audio).rsplit(".", maxsplit=1)[0], i),
            ),
            chunk,
            sr,
        )


if __name__ == "__main__":
    main()