PyAudio正在工作,但每次都会发出错误消息

Question

我正在使用PyAudio来录制麦克风的输入.

由于音频录制对我来说很好,我应该尝试简单地抑制其错误消息吗？还是有办法解决它们？

ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib audio/pcm_bluetooth.c:1613:(audioservice_expect) BT_GET_CAPABILITIES failed : Input/output error(5)
ALSA lib audio/pcm_bluetooth.c:1613:(audioservice_expect) BT_GET_CAPABILITIES failed : Input/output error(5)
ALSA lib audio/pcm_bluetooth.c:1613:(audioservice_expect) BT_GET_CAPABILITIES failed : Input/output error(5)
ALSA lib audio/pcm_bluetooth.c:1613:(audioservice_expect) BT_GET_CAPABILITIES failed : Input/output error(5)
ALSA lib pcm_dmix.c:957:(snd_pcm_dmix_open) The dmix plugin supports only playback stream
ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave
Cannot connect to server socket err = No such file or directory
Cannot connect to server socket
jack server is not running or cannot be started

Answer 1

您可以尝试清理ALSA配置,例如,

ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side

是由/usr/share/alsa/alsa.conf:

pcm.rear cards.pcm.rear
pcm.center_lfe cards.pcm.center_lfe
pcm.side cards.pcm.side

一旦您注释掉这些行,那些错误消息就会消失.您可能还想检查~/.asoundrc和/etc/asound.conf.

这就是说,其中一些消息告诉你的配置有问题,尽管它们不会引起任何实际问题.我不建议您清理alsa.conf它,因为它最初来自ALSA,更新alsa-lib时可能会被覆盖.

有一种方法可以在Python中抑制消息,这里有一个示例代码:

#!/usr/bin/env python
from ctypes import *
import pyaudio

# From alsa-lib Git 3fd4ab9be0db7c7430ebd258f2717a976381715d
# $ grep -rn snd_lib_error_handler_t
# include/error.h:59:typedef void (*snd_lib_error_handler_t)(const char *file, int line, const char *function, int err, const char *fmt, ...) /* __attribute__ ((format (printf, 5, 6))) */;
# Define our error handler type
ERROR_HANDLER_FUNC = CFUNCTYPE(None, c_char_p, c_int, c_char_p, c_int, c_char_p)
def py_error_handler(filename, line, function, err, fmt):
  print 'messages are yummy'
c_error_handler = ERROR_HANDLER_FUNC(py_error_handler)

asound = cdll.LoadLibrary('libasound.so')
# Set error handler
asound.snd_lib_error_set_handler(c_error_handler)
# Initialize PyAudio
p = pyaudio.PyAudio()
p.terminate()

print '-'*40
# Reset to default error handler
asound.snd_lib_error_set_handler(None)
# Re-initialize
p = pyaudio.PyAudio()
p.terminate()

我的电脑输出:

messages are yummy
messages are yummy
messages are yummy
messages are yummy
messages are yummy
messages are yummy
----------------------------------------
ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_dmix.c:957:(snd_pcm_dmix_open) The dmix plugin supports only playback stream
ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave

这些消息由alsa-lib打印出来,而不是PyAudio或PortAudio.代码直接使用alsa-lib snd_lib_error_set_handler函数来设置错误处理程序py_error_handler,您可以使用它来删除任何消息.

我检查过其他Python ALSA绑定,pyalsa和PyAlsaAudio,它们不支持设置错误处理程序.但是,PortAudio 存在问题,所有ALSA错误消息似乎都被抑制了.

Answer 2

所有这些都是真实的,也是一个很好的解决方案.我刚来这里建议一种更好的方法来重用错误处理程序代码:

from ctypes import *
from contextlib import contextmanager
import pyaudio

ERROR_HANDLER_FUNC = CFUNCTYPE(None, c_char_p, c_int, c_char_p, c_int, c_char_p)

def py_error_handler(filename, line, function, err, fmt):
    pass

c_error_handler = ERROR_HANDLER_FUNC(py_error_handler)

@contextmanager
def noalsaerr():
    asound = cdll.LoadLibrary('libasound.so')
    asound.snd_lib_error_set_handler(c_error_handler)
    yield
    asound.snd_lib_error_set_handler(None)

执行此操作后,您可以使用noalsaerr上下文重新使用错误处理程序:

with noalsaerr():
    p = pyaudio.PyAudio()
stream = p.open(format=pyaudio.paFloat32, channels=1, rate=44100, output=1)
...

Answer 3

我面临着同样的问题。

2>/dev/null只需在命令末尾添加即可解决我的问题。我只是想抑制错误消息，它成功了。

例如： python marvin.py 2>/dev/null

Answer 4

sounddevice模块将抑制这些消息，请参阅https://github.com/spatialaudio/python-sounddevice/issues/11。