python - 使用来自现场麦克风的pyaudio检测点击

我将如何使用pyaudio来检测现场麦克风的突然敲击声？

最佳答案

我这样做的一种方式:

一次读取一个样本块，
说0.05秒值得

计算
块的RMS幅度(平方
的平方的均方根
单个样本)

如果块的RMS幅度大于阈值，则为“嘈杂的块”，否则为“安静的块”。

突然轻按可能是一个安静的块，然后是少量的嘈杂块，然后是一个安静的块

如果您从不安静，则您的阈值太低

如果您永远不会收到嘈杂的声音，则说明您的阈值太高

我的应用程序正在录制无人看管的“有趣”噪音，因此只要有嘈杂的声音，它就会录制下来。如果有15秒的嘈杂时间(“遮住耳朵”)，则将阈值乘以1.1；如果有15分钟的安静时间(“更难听”)，则将阈值乘以0.9。您的应用程序将有不同的需求。

此外，刚刚注意到我的代码中有关观察到的RMS值的一些注释。在Macbook Pro的内置麦克风上，标准化的音频数据范围为+/- 1.0，输入音量设置为max，一些数据点:

0.003-0.006(-50dB至-44dB)我家中的中央供暖风扇令人讨厌

在同一台笔记本电脑上键入0.010-0.40(-40dB至-8dB)

0.10(-20dB)在1'距离处轻轻地弹指

0.60(-4.4dB)在1'处大声弹响手指

更新:这是一个入门的示例。

#!/usr/bin/python

# open a microphone in pyAudio and listen for taps

import pyaudio
import struct
import math

INITIAL_TAP_THRESHOLD = 0.010
FORMAT = pyaudio.paInt16
SHORT_NORMALIZE = (1.0/32768.0)
CHANNELS = 2
RATE = 44100
INPUT_BLOCK_TIME = 0.05
INPUT_FRAMES_PER_BLOCK = int(RATE*INPUT_BLOCK_TIME)
# if we get this many noisy blocks in a row, increase the threshold
OVERSENSITIVE = 15.0/INPUT_BLOCK_TIME
# if we get this many quiet blocks in a row, decrease the threshold
UNDERSENSITIVE = 120.0/INPUT_BLOCK_TIME
# if the noise was longer than this many blocks, it's not a 'tap'
MAX_TAP_BLOCKS = 0.15/INPUT_BLOCK_TIME

def get_rms( block ):
    # RMS amplitude is defined as the square root of the
    # mean over time of the square of the amplitude.
    # so we need to convert this string of bytes into
    # a string of 16-bit samples...

    # we will get one short out for each
    # two chars in the string.
    count = len(block)/2
    format = "%dh"%(count)
    shorts = struct.unpack( format, block )

    # iterate over the block.
    sum_squares = 0.0
    for sample in shorts:
        # sample is a signed short in +/- 32768.
        # normalize it to 1.0
        n = sample * SHORT_NORMALIZE
        sum_squares += n*n

    return math.sqrt( sum_squares / count )

class TapTester(object):
    def __init__(self):
        self.pa = pyaudio.PyAudio()
        self.stream = self.open_mic_stream()
        self.tap_threshold = INITIAL_TAP_THRESHOLD
        self.noisycount = MAX_TAP_BLOCKS+1
        self.quietcount = 0
        self.errorcount = 0

    def stop(self):
        self.stream.close()

    def find_input_device(self):
        device_index = None
        for i in range( self.pa.get_device_count() ):
            devinfo = self.pa.get_device_info_by_index(i)
            print( "Device %d: %s"%(i,devinfo["name"]) )

            for keyword in ["mic","input"]:
                if keyword in devinfo["name"].lower():
                    print( "Found an input: device %d - %s"%(i,devinfo["name"]) )
                    device_index = i
                    return device_index

        if device_index == None:
            print( "No preferred input found; using default input device." )

        return device_index

    def open_mic_stream( self ):
        device_index = self.find_input_device()

        stream = self.pa.open(   format = FORMAT,
                                 channels = CHANNELS,
                                 rate = RATE,
                                 input = True,
                                 input_device_index = device_index,
                                 frames_per_buffer = INPUT_FRAMES_PER_BLOCK)

        return stream

    def tapDetected(self):
        print("Tap!")

    def listen(self):
        try:
            block = self.stream.read(INPUT_FRAMES_PER_BLOCK)
        except IOError as e:
            # dammit.
            self.errorcount += 1
            print( "(%d) Error recording: %s"%(self.errorcount,e) )
            self.noisycount = 1
            return

        amplitude = get_rms( block )
        if amplitude > self.tap_threshold:
            # noisy block
            self.quietcount = 0
            self.noisycount += 1
            if self.noisycount > OVERSENSITIVE:
                # turn down the sensitivity
                self.tap_threshold *= 1.1
        else:
            # quiet block.

            if 1 <= self.noisycount <= MAX_TAP_BLOCKS:
                self.tapDetected()
            self.noisycount = 0
            self.quietcount += 1
            if self.quietcount > UNDERSENSITIVE:
                # turn up the sensitivity
                self.tap_threshold *= 0.9

if __name__ == "__main__":
    tt = TapTester()

    for i in range(1000):
        tt.listen()

关于python - 使用来自现场麦克风的pyaudio检测点击，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/4160175/