使用来自现场麦克风的pyaudio检测点击 [英] Detect tap with pyaudio from live mic

问题描述

我将如何使用pyaudio来检测现场麦克风突然发出的敲击声?

How would I use pyaudio to detect a sudden tapping noise from a live microphone?

推荐答案

一种方法:

• 一次读取一块样本， 说值得0.05秒
• 计算 块的RMS幅度(平方 的平方的均方根 单个样本)
• 如果该块的RMS幅度大于阈值，则为嘈杂的块"，否则为安静的块"
• 突然敲击将是一个安静的区域，然后是少量的噪音区域，然后是一个安静的区域
• 如果您从不安静，那么您的门槛太低了
• 如果您永远不会听到嘈杂的声音，则说明您的门槛太高了

• read a block of samples at a time, say 0.05 seconds worth
• compute the RMS amplitude of the block (square root of the average of the squares of the individual samples)
• if the block's RMS amplitude is greater than a threshold, it's a "noisy block" else it's a "quiet block"
• a sudden tap would be a quiet block followed by a small number of noisy blocks followed by a quiet block
• if you never get a quiet block, your threshold is too low
• if you never get a noisy block, your threshold is too high

我的应用程序正在记录无人看管的有趣"噪声，因此只要有嘈杂的块，它就会记录下来.如果有15秒的嘈杂时间段(遮住耳朵")，则将阈值乘以1.1；如果存在15分钟的安静时间段(更难听")，则将阈值乘以0.9. ).您的应用程序将有不同的需求.

My application was recording "interesting" noises unattended, so it would record as long as there were noisy blocks. It would multiply the threshold by 1.1 if there was a 15-second noisy period ("covering its ears") and multiply the threshold by 0.9 if there was a 15-minute quiet period ("listening harder"). Your application will have different needs.

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，输入音量设置为最大值，一些数据点:

Also, just noticed some comments in my code regarding observed RMS values. On the built in mic on a Macbook Pro, with +/- 1.0 normalized audio data range, with input volume set to max, some data points:

• 0.003-0.006(-50dB至-44dB)是我家中令人讨厌的中央暖气风扇
在同一台笔记本电脑上键入
• 0.010-0.40(-40dB至-8dB)
• 0.10(-20dB)在1'距离处轻柔地弹动手指
• 0.60(-4.4dB)在1'处大声弹响手指

• 0.003-0.006 (-50dB to -44dB) an obnoxiously loud central heating fan in my house
• 0.010-0.40 (-40dB to -8dB) typing on the same laptop
• 0.10 (-20dB) snapping fingers softly at 1' distance
• 0.60 (-4.4dB) snapping fingers loudly at 1'

更新:这是一个让您入门的示例.

Update: here's a sample to get you started.

#!/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()

这篇关于使用来自现场麦克风的pyaudio检测点击的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！