关于读取系统声级的最简单方法的任何线索是什么？
我计划创建一个由短 LED 灯带制成的均衡器，并将它们连接到 Arduino 或 RaspberryPi。我已经看到了很多例子，如何使用输入、麦克风等来做到这一点，但对于整体输出却没有那么多。在这一点上，我不在乎程序特定或系统范围，当我真正得到读数时我很高兴。欢迎任何建议。
- 编辑 -
基于如何从 python 中的麦克风获取声音输入，并即时处理它？我将 PCM_CAPTURE 更改为 PCM_PLAYBACK，这导致 python 说在输出/播放时无法读取。
我现在正在尝试创建一个环回设备，其想法是将播放传输回单独的捕获并读取它，但到目前为止还没有运气，我不知道这种方式有多整洁/干净。我真的无法想象这是要走的路。
有人使用 Python 和 PulseAudio 实现了这一点，请参阅此博客文章。作者编写了一个脚本来轮询系统范围的峰值声级，以将其馈送到 VU 表。他还在 Bitbucket 上提供了源代码，请点击此处。
我已经在 Ubuntu 上对其进行了测试，它对我有用（尽管只能从命令行，而不是在交互式 Python 会话中）。涉及的一些额外工作是安装用于与 Python 接口的 ctypes PulseAudio 包装器（源代码中的链接），并可能在脚本中将 SINK_NAME 设置为正确的值。
我从博客 PulseAudio 收集到的内容非常适合这项工作，但也许还有更好的方法。
几乎任何类型的混音器（软件或硬件）都应该能够将声音输出重新路由到输入。对于 Windows，有内置的Stereo Mix，对于 Linux，有几种解决方案（我听说过PulseAudio的好消息，但我无法证明自己——本教程中的一些步骤可能会有所帮助）。
这样你就可以将它路由到 Python - 你已经阅读的麦克风级别的示例应该也可以正常工作。
我找到了这个github 解决方案：
我将 python 程序设置为一个单独的实例，这样它就不会落后于我的主程序。然后每 33 毫秒 (30 fps) 轮询 IPC 泡菜。我稍微修改了代码，如下所示：
#!/usr/bin/env python
# -*- coding: utf-8 -*-
#==============================================================================
#
# vu_meter.py - Listen to microphone left/right and generate vu level
#
#==============================================================================
"""
FROM: https://github.com/kmein/vu-meter
.gitignore NOT INSTALLED
LICENSE NOT INSTALLED
README.md NOT INSTALLED
amplitude.py THIS MODULE
record.py NOT INSTALLED
vu_constants.py THIS MODULE
vu_meter.py THIS MODULE
ENHANCEMENTS:
1) Support Python environment variable for automatic python 2 / 3 selection
2) Add UTF-8 to support Python 2 (not necessary in this program though)
3) Reset maximal between songs (gap when 10 samples of zero strength)
4) Remove console output and write values to ramdisk (/run/user/1000)
5) Optional 'stereo' parameter to measure left & right channels
6) Utilize numpy which is usually auto-installed on distros
7) Include separate amplitute.py & vu_constants.py in main
8) Remove unused functions from Amplitude class
"""
from __future__ import print_function # Must be first import
from __future__ import with_statement # Error handling for file opens
import pyaudio
import numpy as np # January 24, 2021 support separate 2 channels
import sys
import math
import struct
#from amplitude import Amplitude
RATE = 44100
INPUT_BLOCK_TIME = 0.05
INPUT_FRAMES_PER_BLOCK = int(RATE*INPUT_BLOCK_TIME)
SHORT_NORMALIZE = 1.0 / 32768.0
# Mono output
VU_METER_FNAME = "/run/user/1000/mserve.vu-meter-mono.txt"
# Stereo output (Left and Right)
VU_METER_LEFT_FNAME = "/run/user/1000/mserve.vu-meter-left.txt"
VU_METER_RIGHT_FNAME = "/run/user/1000/mserve.vu-meter-right.txt"
class Amplitude(object):
''' an abstraction for Amplitudes (with an underlying float value)
that packages a display function and many more
January 25, 2021 - Remove unused add, subb, gt, eq, int & str functions
'''
def __init__(self, value=0):
self.value = value
def __lt__(self, other):
return self.value < other.value
def to_int(self, scale=1):
''' convert an amplitude to an integer given a scale such that one can
choose the precision of the resulting integer '''
return int(self.value * scale)
@staticmethod
def from_data(block):
''' generate an Amplitude object based on a block of audio input data '''
count = len(block) / 2
shorts = struct.unpack("%dh" % count, block)
sum_squares = sum(s**2 * SHORT_NORMALIZE**2 for s in shorts)
return Amplitude(math.sqrt(sum_squares / count))
def display(self, mark, scale=50, fn=VU_METER_FNAME):
''' display an amplitude and another (marked) maximal Amplitude
graphically '''
int_val = self.to_int(scale)
mark_val = mark.to_int(scale)
delta = abs(int_val - mark_val)
# print(int_val * '*', (delta-1) * ' ', '|',mark_val,int_val,delta)
# January 23, 2021: Write values to ramdisk instead of displaying
with open(fn, "w") as vufile:
vufile.write(str(mark_val) + " " + str(int_val))
def parse_data(data, channel_ndx, channel_cnt, maximal):
'''
Process data from one channel
'''
data = np.fromstring(data,dtype=np.int16)[channel_ndx::channel_cnt]
data = data.tostring()
amp = Amplitude.from_data(data)
gap = amp.value # For signal test below.
if amp > maximal:
maximal = amp
return amp, maximal, gap
def main():
# January 24, 2021 separate left and right channels
parameter = 'mono'
if (len(sys.argv)) == 2:
parameter = sys.argv[1] # Null = 'mono', 'stereo' = Left & Right
audio = pyaudio.PyAudio()
reset_baseline_count = 0
try:
stream = audio.open(format=pyaudio.paInt16,
channels=2,
rate=RATE,
input=True,
frames_per_buffer=INPUT_FRAMES_PER_BLOCK
)
maximal = Amplitude()
maximal_l = maximal_r = maximal
while True:
data = stream.read(INPUT_FRAMES_PER_BLOCK)
# January 24, 2021 separate left and right channels
if parameter == 'stereo':
ampl, maximal_l, gap = parse_data(data, 0, 2, maximal_l)
ampr, maximal_r, gap = parse_data(data, 1, 2, maximal_r)
if maximal_r < maximal_l:
# A momentary spike to left channel inherited by right
maximal_r = maximal_l
if maximal_l < maximal_r:
# A momentary spike to right channel inherited by left
maximal_l = maximal_r
else:
# Mono - processing all dadta
amp = Amplitude.from_data(data)
gap = amp.value # For signal test below.
if amp > maximal:
maximal = amp
# New code January 23, to reset next song's maximal during gap
if gap == 0.0:
reset_baseline_count += 1
if reset_baseline_count == 10:
maximal = Amplitude()
maximal_l = maximal_r = maximal
# print('maximual reset', maximal.value)
else:
reset_baseline_count = 0
# January 24, 2021 separate left and right channels
if parameter == 'stereo':
ampl.display(scale=200, mark=maximal_l, fn=VU_METER_LEFT_FNAME)
ampr.display(scale=200, mark=maximal_r, fn=VU_METER_RIGHT_FNAME)
else:
# Mono processing one channel combined sound
amp.display(scale=200, mark=maximal, fn=VU_METER_FNAME)
finally:
stream.stop_stream()
stream.close()
audio.terminate()
if __name__ == "__main__":
main()