树莓派3 Model B+在Python语音识别中无法使用USB麦克风求助

环境说明 #

• 设备：树莓派3 Model B+
• 音频输入：音频插孔麦克风搭配aux-usb转换器，USB设备编号为2
• 现状：arecord命令可正常录制音频，但运行Python语音识别代码时抛出大量ALSA相关错误

错误日志 #

ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.front.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM front
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround51.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround21
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround51.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround21
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround40.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround40
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround51.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround41
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround51.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround50
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround51.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround51
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.surround71.0:CARD=0'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM surround71
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.iec958.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM iec958
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.iec958.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM spdif
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.iec958.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM spdif
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.hdmi
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.hdmi
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_a52.c:823:(_snd_pcm_a52_open) a52 is only for playback
ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835_hdmi.pcm.iec958.0:CARD=0,AES0=6,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:4568:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5047:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2565:(snd_pcm_open_noupdate) Unknown PCM iec958:{AES0 0x6 AES1 0x82 AES2 0x0 AES3 0x2  CARD 0}
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock

测试代码 #

import speech_recognition as sr
from datetime import date


r = sr.Recognizer()
mic = sr.Microphone(device_index=2)

print("hello")

while True:
    with mic as source:
        audio = r.listen(source)
    words = r.recognize_google(audio)
    print(words)

解决步骤 #

1. 明确指定麦克风参数 #

speech_recognition可能默认调用系统默认音频设备，而默认配置指向了未启用的HDMI音频。修改代码，指定采样率或设备硬件地址：

# 指定采样率（USB麦克风常用16000或44100）
mic = sr.Microphone(device_index=2, sample_rate=16000)

# 或者直接指定设备硬件地址，先通过`arecord -l`查看，比如hw:2,0
mic = sr.Microphone(device_name="hw:2,0")

2. 修改ALSA默认配置 #

创建或编辑用户级ALSA配置文件~/.asoundrc，将默认音频设备指向编号2的USB设备：

nano ~/.asoundrc

添加以下内容并保存：

pcm.!default {
    type hw
    card 2
}

ctl.!default {
    type hw
    card 2
}

重启Python脚本即可生效。

3. 修复依赖缺失 #

错误中提到Jack服务器问题，安装相关依赖并升级pyaudio：

sudo apt-get install libjack-jackd2-dev portaudio19-dev
pip install --upgrade pyaudio

4. 添加代码异常处理 #

原代码未处理识别失败或网络错误，添加异常处理避免崩溃：

import speech_recognition as sr

r = sr.Recognizer()
mic = sr.Microphone(device_index=2, sample_rate=16000)

print("hello")

while True:
    with mic as source:
        r.adjust_for_ambient_noise(source)  # 自动调整环境噪音阈值
        print("正在监听...")
        audio = r.listen(source)
    try:
        # 指定识别语言，比如中文zh-CN
        words = r.recognize_google(audio, language="zh-CN")
        print(words)
    except sr.UnknownValueError:
        print("无法识别音频内容")
    except sr.RequestError as e:
        print(f"请求Google语音识别服务失败: {e}")

内容的提问来源于stack exchange，提问作者Jibreel Natsheh