基于python的实时音频信号处理

Question

我一直在尝试使用python中的“pyAudio”模块进行实时音频信号处理。我所做的只是一个简单的例子，从麦克风读取音频数据并通过耳机播放。我尝试了以下代码（Python和Cython版本）。我以为它能用，但不幸的是它太慢了，不够光滑。我该如何改进代码，使其能够顺利运行。我的电脑是i7，8GB内存。

Python版本

import pyaudio
import numpy as np

RATE    = 16000
CHUNK   = 256

p               =   pyaudio.PyAudio()

player = p.open(format=pyaudio.paInt16, channels=1, rate=RATE, output=True, 
frames_per_buffer=CHUNK)
stream = p.open(format=pyaudio.paInt16, channels=1, rate=RATE, input=True, frames_per_buffer=CHUNK)

for i in range(int(20*RATE/CHUNK)): #do this for 10 seconds
player.write(np.fromstring(stream.read(CHUNK),dtype=np.int16))
stream.stop_stream()
stream.close()
p.terminate()

Cython版本

import pyaudio
import numpy as np

cdef int RATE   = 16000
cdef int CHUNK  = 1024
cdef int i      
p               =   pyaudio.PyAudio()

player = p.open(format=pyaudio.paInt16, channels=1, rate=RATE, output=True, frames_per_buffer=CHUNK)
stream = p.open(format=pyaudio.paInt16, channels=1, rate=RATE, input=True, frames_per_buffer=CHUNK)

for i in range(500): #do this for 10 seconds
    player.write(np.fromstring(stream.read(CHUNK),dtype=np.int16))
stream.stop_stream()
stream.close()
p.terminate()

Answer 1

下面的代码将采用默认输入设备，并将记录的内容输出到默认输出设备中。

import PyAudio
import numpy as np

p = pyaudio.PyAudio()

CHANNELS = 2
RATE = 44100

def callback(in_data, frame_count, time_info, flag):
    # using Numpy to convert to array for processing
    # audio_data = np.fromstring(in_data, dtype=np.float32)
    return in_data, pyaudio.paContinue

stream = p.open(format=pyaudio.paFloat32,
                channels=CHANNELS,
                rate=RATE,
                output=True,
                input=True,
                stream_callback=callback)

stream.start_stream()

while stream.is_active():
    time.sleep(20)
    stream.stop_stream()
    print("Stream is stopped")

stream.close()

p.terminate()

这将持续20秒并停止。方法回调用于处理信号： audio_data = np.fromstring(in_data, dtype=np.float32)

return in_data是将后处理数据发送回输出设备的位置。

注释块的默认参数为1024，如PyAudio文档中所述： http://people.csail.mit.edu/hubert/pyaudio/docs/#pyaudio.PyAudio.open

Answer 2

我正在做一个类似的项目。我修改了你的代码，现在摊位都不见了。大块越大，延迟越大。所以我把它放低了。

import pyaudio
import numpy as np

CHUNK = 2**5
RATE = 44100
LEN = 10

p = pyaudio.PyAudio()

stream = p.open(format=pyaudio.paInt16, channels=1, rate=RATE, input=True, frames_per_buffer=CHUNK)
player = p.open(format=pyaudio.paInt16, channels=1, rate=RATE, output=True, frames_per_buffer=CHUNK)


for i in range(int(LEN*RATE/CHUNK)): #go for a LEN seconds
    data = np.fromstring(stream.read(CHUNK),dtype=np.int16)
    player.write(data,CHUNK)


stream.stop_stream()
stream.close()
p.terminate()

Answer 3

我相信您缺少CHUNK作为player.write调用的第二个参数。

player.write(np.fromstring(stream.read(CHUNK),dtype=np.int16),CHUNK)

另外，不确定它的格式是否有错误。但是player.write需要被标记到for循环中

每pyaudio site需要RATE / CHUNK * RECORD_SECONDS，而不是RECORD *RATE/CHUNK，因为python在/除法之前执行*乘法。

for i in range(int(20*RATE/CHUNK)): #do this for 10 seconds
    player.write(np.fromstring(stream.read(CHUNK),dtype=np.int16),CHUNK)

stream.stop_stream()
stream.close()
p.terminate()

最后，您可能需要将rate增加到44100，将CHUNK增加到1024，并将CHANNEL增加到2以获得更好的保真度。