Python: OSError: [Errno -9985] Device unavailable when using Snowboy and SpeechRecognition on Raspberry PI 3B+

Question

我正在我的 3B+ 上构建个人助理。我现在想做的是使用 Snowboy 检测我的热词（完美无缺），然后在检测到热词后，使用 SpeechRecognizer 接收语音命令。热词检测工作正常，调用 sr.Microphone() 时发生错误。

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

Snowboy 工作正常。程序按预期运行，直到检测到热词。我认为这一定与 Snowboy 和 SpeechRecognition 试图使用麦克风这一事实有关。另请注意，SpeechRecognition 本身可以正常工作。如果我创建一个只使用 SpeechRecognition 而不是 Snowboy 的程序，它会按预期工作。

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

如果我能提供更多信息，请告诉我。

Answer 1

解决方法是在初始化麦克风之前终止snowboy 例如：

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，两者（Snowboy 和 SpeechRec）都尝试连接到您的麦克风。并且第二次连接尝试将被拒绝。

几天前我遇到了同样的问题。 @Mezex 的解决方案很好，在我的情况下需要很长时间才能关闭 Snowboy 并打开 SpeechRec（大约 2 或 3 秒，直到它准备好收听）

我的方案参考了ALSA。有个插件叫dsnoop，有点类似于设备文件，可以被多个程序调用。

文件 /etc/asound.config 决定了如何处理您的 hole 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获得您麦克风的名称 In my case it is "wm8960soundcard"

默认调用pcm.!default。它引用 caputre 的输入流（您的麦克风），它引用 array。这是通过多个任务同时调用的 type dsnoop。

看看https://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html，插件列表都有

我知道这有点复杂，但对我来说这是最好的解决方案。希望对您有所帮助。

Python: OSError: [Errno -9985] Device unavailable when using Snowboy and SpeechRecognition on Raspberry PI 3B+

Python: OSError: [Errno -9985] Device unavailable when using Snowboy and SpeechRecognition on Raspberry PI 3B+

speech-recognition

python-3.x

raspberry-pi3

snowboy

raspbian-buster