Python麦克风输入和低通滤波器实时实现

Question

我正在尝试使用树莓派接收麦克风输入并添加效果，实时输出麦克风输入的低通音频滤波器效果。他们的许多蟒蛇音频库就像声音pi / py音频一样。如果任何人可以帮助我如何实现这一目标。

亲切的问候。

Answer 1

我没有树莓派，但我在Windows上尝试过与python类似的东西。我假设您可以修改此程序以满足您的需求。

为此，您需要安装pyaudio
pip install pyaudio

您可以从here

下载python sounddevice

该计划：
录制麦克风音频
使用限制器限制音频
播放修改后的音频
绘制原始音频和修改音频

Python代码

from pyaudio import PyAudio, paContinue, paFloat32
from time import sleep
from numpy import array, random, arange, float32, float64, zeros
import matplotlib.pyplot as plt
import sounddevice as sd

################################### Constants ##################################

fs            = 44100   # Hz
threshold     = 0.8     # absolute gain
delay         = 40      # samples
signal_length = 1      # second
release_coeff = 0.5555  # release time factor
attack_coeff  = 0.5     # attack time factor
dtype         = float32 # default data type
block_length  = 1024    # samples

############################# Implementation of Limiter ########################

class Limiter:
    def __init__(self, attack_coeff, release_coeff, delay, dtype=float32):
        self.delay_index = 0
        self.envelope = 0
        self.gain = 1
        self.delay = delay
        self.delay_line = zeros(delay, dtype=dtype)
        self.release_coeff = release_coeff
        self.attack_coeff = attack_coeff

    def limit(self, signal, threshold):
        for i in arange(len(signal)):
            self.delay_line[self.delay_index] = signal[i]
            self.delay_index = (self.delay_index + 1) % self.delay

            # calculate an envelope of the signal
            self.envelope *= self.release_coeff
            self.envelope  = max(abs(signal[i]), self.envelope)

            # have self.gain go towards a desired limiter gain
            if self.envelope > threshold:
                target_gain = (1+threshold-self.envelope)
            else:
                target_gain = 1.0
            self.gain = ( self.gain*self.attack_coeff +
                          target_gain*(1-self.attack_coeff) )

            # limit the delayed signal
            signal[i] = self.delay_line[self.delay_index] * self.gain



################### Record Audio from Microphone #########################    

print "Recording Audio"
signal = sd.rec(signal_length * fs, samplerate=fs, channels=1, dtype=dtype)
sd.wait()
print "Audio recording complete , Play Audio"



################################# Play the Audio ###############################

original_signal = array(signal, copy=True, dtype=dtype)
limiter = Limiter(attack_coeff, release_coeff, delay, dtype)

def callback(in_data, frame_count, time_info, flag):
    if flag:
        print("Playback Error: %i" % flag)
    played_frames = callback.counter
    callback.counter += frame_count
    limiter.limit(signal[played_frames:callback.counter], threshold)
    return signal[played_frames:callback.counter], paContinue

callback.counter = 0

pa = PyAudio()

stream = pa.open(format = paFloat32,
                 channels = 1,
                 rate = fs,
                 frames_per_buffer = block_length,
                 output = True,
                 stream_callback = callback)

while stream.is_active():
    sleep(0.1)

stream.close()
pa.terminate()

############################## Plot results ####################################

plt.figure()
plt.plot(original_signal, color='green', label='original signal')
plt.plot(signal, color='red', label='limited signal')
plt.legend()
plt.show(block=True)
############################## End Program ####################################

终端输出

Python 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>> 
Recording Audio
Audio recording complete , Play Audio
>>> 

图像输出