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60 lines
2.2 KiB
60 lines
2.2 KiB
3 years ago
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# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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class Frame(object):
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"""Represents a "frame" of audio data."""
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def __init__(self, bytes, timestamp, duration):
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self.bytes = bytes
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self.timestamp = timestamp
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self.duration = duration
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class ChunkBuffer(object):
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def __init__(self,
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frame_duration_ms=80,
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shift_ms=40,
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sample_rate=16000,
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sample_width=2):
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self.sample_rate = sample_rate
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self.frame_duration_ms = frame_duration_ms
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self.shift_ms = shift_ms
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self.remained_audio = b''
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self.sample_width = sample_width # int16 = 2; float32 = 4
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def frame_generator(self, audio):
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"""Generates audio frames from PCM audio data.
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Takes the desired frame duration in milliseconds, the PCM data, and
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the sample rate.
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Yields Frames of the requested duration.
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"""
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audio = self.remained_audio + audio
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self.remained_audio = b''
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n = int(self.sample_rate *
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(self.frame_duration_ms / 1000.0) * self.sample_width)
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shift_n = int(self.sample_rate *
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(self.shift_ms / 1000.0) * self.sample_width)
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offset = 0
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timestamp = 0.0
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duration = (float(n) / self.sample_rate) / self.sample_width
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shift_duration = (float(shift_n) / self.sample_rate) / self.sample_width
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while offset + n <= len(audio):
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yield Frame(audio[offset:offset + n], timestamp, duration)
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timestamp += shift_duration
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offset += shift_n
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self.remained_audio += audio[offset:]
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