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import pyaudio as pa
from array import array
def _createClickSample(clickFrequency: int, samplingRate: int) -> array:
clickDuration = 0.03 # seconds
sampleLength = int(clickDuration * samplingRate)
fadeSamples = 50
amplitude = 0.8
attackEnv = [(i/fadeSamples) * amplitude for i in range(1, fadeSamples, 1)]
releaseEnv = [(i/fadeSamples) * amplitude for i in range(fadeSamples, 0, -1)]
amplitudeEnv = attackEnv + [amplitude] * (sampleLength - len(attackEnv) - len(releaseEnv)) + releaseEnv
cycleLength = (1 / clickFrequency) * samplingRate
from math import sin, pi
return array('h', [int(sin(((i % cycleLength) / cycleLength) * 2 * pi) * amplitudeEnv[i] * 32767) for i in range(sampleLength)])
def _createOutputBuffer(bpm: int, clickFrequency: int, samplingRate: int) -> array:
clickSample = _createClickSample(clickFrequency, samplingRate)
samplesPerBeat = int((60 / bpm) * samplingRate)
assert len(clickSample) <= samplesPerBeat
return clickSample + array('h', [0] * (samplesPerBeat - len(clickSample)))
class Metronome:
def __init__(self, bufferSize: int, samplingRate: int):
self._bufferSize = bufferSize
self._samplingRate = samplingRate
self._sampleFormat = pa.paInt16
self._channels = 1
self._pa = pa.PyAudio()
self._stream = None
self._bufferPointer = 0
self._outputBuffer = array('h')
def __del__(self):
if self.running:
self._stream.stop_stream()
self._stream.close()
def _callback(self, inData, frameCount, timeInfo, statusFlags):
leftover = len(self._outputBuffer) - self._bufferPointer
if frameCount > leftover:
outData = self._outputBuffer[self._bufferPointer:] + self._outputBuffer[0:frameCount - leftover]
self._bufferPointer = frameCount - leftover
else:
outData = self._outputBuffer[self._bufferPointer:self._bufferPointer + frameCount]
self._bufferPointer += frameCount
assert self._bufferPointer >= 0 and self._bufferPointer <= len(self._outputBuffer)
return (outData.tobytes(), pa.paContinue)
def start(self, bpm: int, clickFrequency: int) -> None:
if self.running:
return
self._bufferPointer = 0
self._outputBuffer = _createOutputBuffer(bpm, clickFrequency, self._samplingRate)
self._stream = self._pa.open(format=self._sampleFormat,
channels=self._channels,
rate=self._samplingRate,
frames_per_buffer=self._bufferSize,
output=True,
stream_callback=self._callback)
def stop(self) -> None:
if not self.running:
return None
self._stream.stop_stream()
self._stream.close()
self._stream = None
@property
def running(self) -> bool:
return self._stream is not None
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