Python: OSError：[Errno -9985]在树莓派3B+上使用雪童和SpeechRecognition时设备不可用

Question

我正在我的3B+上构建一个个人助理。我现在要做的就是用雪花公子来检测我的热词(工作得很完美)，然后在检测到热词之后，用SpeechRecognizer来接收语音命令。热词检测工作正常，错误发生在调用sr.Microphone()时。

示例代码：

import speech_recognition as sr
import snowboydecoder

def detected_callback():
    r = sr.Recognizer()
    with sr.Microphone() as source:
        print('Ready...')
        r.adjust_for_ambient_noise(source, duration=.2)
        audio = r.listen(source)

    try:
        command = r.recognize_google(audio).lower()
        print('You said: ' + command + '\n')

    except sr.UnknownValueError:
        print('Your last command couldn\'t be heard')
        comand = None

detector = snowboydecoder.HotwordDetector("SnowboyDependencies/Ancilla.pmdl", sensitivity=.5, audio_gain=1)
detector.start(detected_callback)

我收到以下输出：

INFO:snowboy:Keyword 1 detected at time: 2020-03-24 21:53:35
Expression 'ret' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 1736
Expression 'AlsaOpen( &alsaApi->baseHostApiRep, params, streamDir, &self->pcm )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 1904
Expression 'PaAlsaStreamComponent_Initialize( &self->capture, alsaApi, inParams, StreamDirection_In, NULL != callback )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 2171
Expression 'PaAlsaStream_Initialize( stream, alsaHostApi, inputParameters, outputParameters, sampleRate, framesPerBuffer, callback, streamFlags, userData )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 2840
Traceback (most recent call last):
  File "sttTest.py", line 43, in <module>
    detector.start(detected_callback)
  File "/home/pi/AncillaFiles/SnowboyDependencies/snowboydecoder.py", line 221, in start
    callback()
  File "sttTest.py", line 27, in detected_callback
    with sr.Microphone(device_index = 2, sample_rate = 44100, chunk_size = 512) as source:
  File "/home/pi/.local/lib/python3.7/site-packages/speech_recognition/__init__.py", line 141, in __enter__
    input=True,  # stream is an input stream
  File "/usr/local/lib/python3.7/dist-packages/pyaudio.py", line 750, in open
    stream = Stream(self, *args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/pyaudio.py", line 441, in __init__
    self._stream = pa.open(**arguments)
OSError: [Errno -9985] Device unavailable

雪童工作得很好。程序按预期运行，直到检测到hotword为止。我想这一定与雪童和SpeechRecognition试图使用麦克风的事实有关。还要注意的是，SpeechRecognition本身工作得很好。如果我创建了一个只使用SpeechRecognition而不使用雪人的程序，它会按预期工作。

我在运行Raspbian Buster的Raspberry Pi 3b+上使用Python3。

如果我能提供更多信息，请让我知道。

Answer 1

解决方案是在初始化麦克风Ex之前终止snowboy：

import speech_recognition as sr
import snowboydecoder

def detected_callback():
    detector.terminate() #change here
    r = sr.Recognizer()
    with sr.Microphone() as source:
        print('Ready...')
        r.adjust_for_ambient_noise(source, duration=.2)
        audio = r.listen(source)

    try:
        command = r.recognize_google(audio).lower()
        print('You said: ' + command + '\n')

    except sr.UnknownValueError:
        print('Your last command couldn\'t be heard')
        comand = None

detector = snowboydecoder.HotwordDetector("SnowboyDependencies/Ancilla.pmdl", sensitivity=.5, audio_gain=1)
detector.start(detected_callback)

Answer 2

问题是，(雪人和SpeechRec)都试图连接到你的麦克风。并且第二个连接尝试将被拒绝。

几天前我也遇到了同样的问题。来自@Mezex的解决方案很好，在我的情况下，只需很长时间就可以关闭雪人男孩并打开SpeechRec (大约2到3秒，直到它准备好收听)

我的解决方案是ALSA。有一个名为dsnoop的插件，它类似于设备文件，可以被多个程序调用。

文件/etc/asound.config决定如何处理您的孔操作系统的声音。如果将其更改为：

defaults.pcm.rate_converter "samplerate"

pcm.!default {
    type asym
    playback.pcm "playback"
    capture.pcm "capture"
}

pcm.playback {
    type plug
    slave.pcm "dmixed"
}

pcm.capture {
    type plug
    slave.pcm "array"
}

pcm.dmixed {
    type dmix
    slave.pcm "hw:name_of_your_speaker"
    ipc_key 555555
}

pcm.array {
    type dsnoop
    slave {
        pcm "hw:name_of_your_Mic"
        channels 2
    }
    ipc_key 666666
}

并删除您的~/asoundrc文件，它应该可以工作。

您将通过arecord -l In my case it is "wm8960soundcard"获得麦克风的名称

默认情况下会调用pcm.!default。它指的是caputre的输入流(麦克风)，后者指的是array。这是通过可由多个任务同时调用的type dsnoop实现的。

看看https://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html，里面列出了所有的插件

我知道这有点复杂，但对我来说这是最好的解决方案。希望这能帮上忙。