树莓派Raspberry Pi中使用PyAudio实现语音捕获及回放

注意：有个重要的问题，树莓派板载中没有MIC输入接口，需要外加USB声卡实现录音功能。而且要有耐心，声卡顺序等配置不当事，使用PyAudio稍有不当就会引起内核崩溃。耐心调整。

安装树莓派到tf卡

下载最新版本的raspbian，它有两个版本，如果你不需要桌面环境，可以下载lite版本，下载地址为：https://www.raspberrypi.org/downloads/ 下载完后是个zip包，请解压缩。

Mac电脑里请使用以下步骤：

插入tf读卡器并插入要写入镜像的tf卡，然后umount它，为写入准备

$ diskutil list
$ df
$ diskutil umount /dev/disk3s1

把解压后的img后缀的镜像写入tf卡里，完成后弹出tf卡，并取下插入树莓派

sudo dd bs=1m if=2017-11-29-raspbian-stretch-lite.img of=/dev/disk3 conv=sync
sudo diskutil eject /dev/disk3

树莓派默认安装后没有开启ssh，请连接鼠标、键盘、显示器登录本机开启ssh服务，默认的用户名为：pi 密码为： raspberry，登录后使用raspi-config开启ssh服务；

sudo raspi-config

更新系统并安装一些必要的工具

sudo apt-get update
sudo apt-get -y upgrade
sudo apt-get install -y git
sudo apt-get install -y python-pip

安装PyAudio

二进制安装

sudo apt-get install -y python-pyaudio

从源码安装

sudo apt-get install -y libportaudio0 libportaudio2 libportaudiocpp0 portaudio19-dev
sudo apt-get install -y python-dev
git clone http://people.csail.mit.edu/hubert/git/pyaudio.git
cd pyaudio
sudo python setup.py install

测试PyAudio

查看系统中的声卡顺序，在录音时要使用这里使用list.py获取设备信息，执行时可能会返回一些错误，不影响使用。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pyaudio
po = pyaudio.PyAudio()
for index in range(po.get_device_count()): 
    desc = po.get_device_info_by_index(index)
    #print desc
    print "index:%-5d  maxInputChannels: %-5d  device: %-40s  rate: %-10d" %  (index, desc["maxInputChannels"], desc["name"],  int(desc["defaultSampleRate"]))

python list.py

开始录音测试，使用record.py录音5秒，程序中使用的input_device_index=0要跟录音设备一致，否则可能引起系统内核崩溃，这个顺序是声卡的顺序，不受默认声卡配置影响，但是默认声卡会影响错误信息的输出。

# -*- coding:utf-8 -*-
import os
import pyaudio
import wave
import sys

CHUNK = 512
FORMAT = pyaudio.paInt16
CHANNELS = 1
RATE = 44100
RECORD_SECONDS = 5
WAVE_OUTPUT_FILENAME = "output.wav"

p = pyaudio.PyAudio()

stream = p.open(format=FORMAT,
                channels=CHANNELS,
                rate=RATE,
                input=True, input_device_index=2,
                frames_per_buffer=CHUNK)

print("* recording")

frames = []

for i in range(0, int(RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)
    frames.append(data)

print("* done recording")

stream.stop_stream()
stream.close()
p.terminate()

wf_path = os.path.join(sys.path[0], WAVE_OUTPUT_FILENAME)
wf = wave.open(wf_path, 'wb')
wf.setnchannels(CHANNELS)
wf.setsampwidth(p.get_sample_size(FORMAT))
wf.setframerate(RATE)
wf.writeframes(b''.join(frames))
wf.close()
print(wf_path)

python record.py

完成录音后，进行播放时需要播放软件，可以使用sox工具

sudo apt-get install -y sox

安装后play命令可用

play output.wav

估计你play时会遇到问题，USB默认顺序有可能不在0，而是1或者其它顺序，需要查看/proc/asound/cards确认回放设备的顺序

pi@raspberrypi:~ $ cat /proc/asound/cards
 0 [ALSA           ]: bcm2835 - bcm2835 ALSA
                      bcm2835 ALSA
 1 [Audio          ]: USB-Audio - USB Audio
                      Generic USB Audio at usb-3f980000.usb-1.4, high speed

然后在播放是使用参数指定

AUDIODEV=hw:1,0 play output.wav

调试声卡

还有好多调整声卡顺序、设置默认设备顺序的方式可以尝试一下；不过有可能出现各种各样的问题，甚至内核崩溃，这些之前都遇到过。

查看声卡信息

查看声卡的顺序

pi@raspberrypi:~ $ cat /proc/asound/cards 
 0 [ALSA           ]: bcm2835 - bcm2835 ALSA
                      bcm2835 ALSA
 1 [Audio          ]: USB-Audio - USB Audio
                      Generic USB Audio at usb-3f980000.usb-1.4, high speed

查看回放设备

pi@raspberrypi:~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Audio [USB Audio], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

查看录音设备

pi@raspberrypi:~ $ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Audio [USB Audio], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

查看设备名称和详细信息可以使用aplay -L或者arecord -L，用户可以根据这个名称信息选择播放或者采集设备

pi@raspberrypi:~ $ aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
default:CARD=ALSA
    bcm2835 ALSA, bcm2835 ALSA
    Default Audio Device
sysdefault:CARD=ALSA
    bcm2835 ALSA, bcm2835 ALSA
    Default Audio Device
dmix:CARD=ALSA,DEV=0
    bcm2835 ALSA, bcm2835 ALSA
    Direct sample mixing device
dmix:CARD=ALSA,DEV=1
    bcm2835 ALSA, bcm2835 IEC958/HDMI
    Direct sample mixing device
dsnoop:CARD=ALSA,DEV=0
    bcm2835 ALSA, bcm2835 ALSA
    Direct sample snooping device
dsnoop:CARD=ALSA,DEV=1
    bcm2835 ALSA, bcm2835 IEC958/HDMI
    Direct sample snooping device
hw:CARD=ALSA,DEV=0
    bcm2835 ALSA, bcm2835 ALSA
    Direct hardware device without any conversions
hw:CARD=ALSA,DEV=1
    bcm2835 ALSA, bcm2835 IEC958/HDMI
    Direct hardware device without any conversions
plughw:CARD=ALSA,DEV=0
    bcm2835 ALSA, bcm2835 ALSA
    Hardware device with all software conversions
plughw:CARD=ALSA,DEV=1
    bcm2835 ALSA, bcm2835 IEC958/HDMI
    Hardware device with all software conversions
default:CARD=Audio
    USB Audio, USB Audio
    Default Audio Device
sysdefault:CARD=Audio
    USB Audio, USB Audio
    Default Audio Device
front:CARD=Audio,DEV=0
    USB Audio, USB Audio
    Front speakers
surround21:CARD=Audio,DEV=0
    USB Audio, USB Audio
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=Audio,DEV=0
    USB Audio, USB Audio
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Audio,DEV=0
    USB Audio, USB Audio
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Audio,DEV=0
    USB Audio, USB Audio
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Audio,DEV=0
    USB Audio, USB Audio
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Audio,DEV=0
    USB Audio, USB Audio
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Audio,DEV=0
    USB Audio, USB Audio
    IEC958 (S/PDIF) Digital Audio Output
dmix:CARD=Audio,DEV=0
    USB Audio, USB Audio
    Direct sample mixing device
dsnoop:CARD=Audio,DEV=0
    USB Audio, USB Audio
    Direct sample snooping device
hw:CARD=Audio,DEV=0
    USB Audio, USB Audio
    Direct hardware device without any conversions
plughw:CARD=Audio,DEV=0
    USB Audio, USB Audio
    Hardware device with all software conversions

采集并回放

pi@raspberrypi:~ $ alsaloop -Cplughw:CARD=Audio -Pplughw:CARD=Audio

录音

arecord -D "plughw:1,0" -f S16_LE -r 8000 -d 5 arecord.wav

设置默认声卡

 $ sudo nano /etc/asound.conf

内容如下：

defaults.ctl.card 1
defaults.pcm.card 1
defaults.timer.card 1

重启生效，可对sox的play、arecord、aplay等程序生效，对于alsaloop不起作用。

可使用alsamixer查看默认声卡。

注意：上面的方式有时会引起内核崩溃，采用如下方式目前测试还未发现内核崩溃问题

nano ~/.asoundrc

内容如下，修改后重新运行程序，立即生效

pcm.!default{
  type asym
  playback.pcm{
    type plug
    slave.pcm "hw:1,0"
  }
  capture.pcm{
    type plug
    slave.pcm "hw:1,0"
  }
}

调整USB声卡顺序

调整USB声卡顺序到0，新建立一个文件/lib/modprobe.d/sagelit.conf ，内容如下

# Load USB audio before the internal soundcard
options snd_usb_audio index=0
options snd_bcm2835 index=1
# Make sure the sound cards are ordered the correct way in ALSA
options snd slots=snd_usb_audio,snd_bcm2835

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