PyAudio 未捕获正确的音频数据

Question

我无法获取 PyAudio 流来从我的 USB 麦克风捕获音频数据。

我正在 Ubuntu 上运行 Python 程序（Ubuntu 14.04.3 LTS）。我已将 ALSA 配置为将我的 USB 麦克风设置为默认声卡，并通过运行测试这项工作是否正常：

arecord -D plughw:0,0 -f cd test.wav

然后使用播放该音频

aplay -D plughw:0,0 test.wav

我的/etc/modprobe.d/alsa-base.conf 文件如下所示：

# autoloader aliases
install sound-slot-0 /sbin/modprobe snd-card-0
install sound-slot-1 /sbin/modprobe snd-card-1
install sound-slot-2 /sbin/modprobe snd-card-2
install sound-slot-3 /sbin/modprobe snd-card-3
install sound-slot-4 /sbin/modprobe snd-card-4
install sound-slot-5 /sbin/modprobe snd-card-5
install sound-slot-6 /sbin/modprobe snd-card-6
install sound-slot-7 /sbin/modprobe snd-card-7

# Cause optional modules to be loaded above generic modules
install snd /sbin/modprobe --ignore-install snd $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-ioctl32 ; /sbin/modprobe --quiet --use-blacklist snd-seq ; }
#
# Workaround at bug #499695 (reverted in Ubuntu see LP #319505)
install snd-pcm /sbin/modprobe --ignore-install snd-pcm $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-pcm-oss ; : ; }
install snd-mixer /sbin/modprobe --ignore-install snd-mixer $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-mixer-oss ; : ; }
install snd-seq /sbin/modprobe --ignore-install snd-seq $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; /sbin/modprobe --quiet --use-blacklist snd-seq-oss ; : ; }
#
install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; : ; }
# Cause optional modules to be loaded above sound card driver modules
install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-emu10k1-synth ; }
install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq ; }

# Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway)
install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist saa7134-alsa ; : ; }
# Prevent abnormal drivers from grabbing index 0
options bt87x index=-2
options cx88_alsa index=-2
options saa7134-alsa index=-2
options snd-atiixp-modem index=-2
options snd-intel8x0m index=-2
options snd-via82xx-modem index=-2
# options snd-usb-audio index=-2
options snd-usb-audio index=0
options snd-usb-caiaq index=-2
options snd-usb-ua101 index=-2
options snd-usb-us122l index=-2
options snd-usb-usx2y index=-2
# Ubuntu #62691, enable MPU for snd-cmipci
options snd-cmipci mpu_port=0x330 fm_port=0x388
# Keep snd-pcsp from being loaded as first soundcard
options snd-pcsp index=-2

我已经成功安装了 PyAudio，但是当我打开一个流时，我没有得到任何音频数据。我的理解是使用 PyAudio 打开流时使用默认设备（除非我没有设置的 input_device_index 参数另有指定）。

    p = pyaudio.PyAudio()
    stream = p.open(
        format=pyaudio.paInt16,
        channels=1,
        rate=18000,
        input=True,
        frames_per_buffer=1024
    )

当我运行PyAudio().get_device_info_by_index(0) 时，我得到：

{'defaultSampleRate': 16000.0, 'defaultLowOutputLatency': 0.0239375, 'defaultLowInputLatency': 0.0239375, 'maxInputChannels': 1L, 'structVersion': 2L, 'hostApi': 0L, 'index': 0, 'defaultHighOutputLatency': 0.096, 'maxOutputChannels': 2L, 'name': u'Jabra SPEAK 410 USB: Audio (hw:0,0)', 'defaultHighInputLatency': 0.096}

^（Jabra SPEAK 410 USB：音频）是我的 USB 麦克风。

这些是 PyAudio 在加载时（甚至在打开流之前）吐出的日志。不过，我在网上阅读过，我可以忽略大部分错误。

ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib confmisc.c:1286:(snd_func_refer) Unable to find definition 'cards.USB-Audio.pcm.hdmi.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM hdmi
ALSA lib confmisc.c:1286:(snd_func_refer) Unable to find definition 'cards.USB-Audio.pcm.hdmi.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM hdmi
ALSA lib confmisc.c:1286:(snd_func_refer) Unable to find definition 'cards.USB-Audio.pcm.modem.0:CARD=0'
ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline:CARD=0,DEV=0
ALSA lib confmisc.c:1286:(snd_func_refer) Unable to find definition 'cards.USB-Audio.pcm.modem.0:CARD=0'
ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline:CARD=0,DEV=0
ALSA lib confmisc.c:1286:(snd_func_refer) Unable to find definition 'cards.USB-Audio.pcm.modem.0:CARD=0'
ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM phoneline
ALSA lib confmisc.c:1286:(snd_func_refer) Unable to find definition 'cards.USB-Audio.pcm.modem.0:CARD=0'
ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM phoneline
bt_audio_service_open: connect() failed: Connection refused (111)
bt_audio_service_open: connect() failed: Connection refused (111)
bt_audio_service_open: connect() failed: Connection refused (111)
bt_audio_service_open: connect() failed: Connection refused (111)
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

看起来流打开时正在收集数据，但没有捕获任何声音。我的麦克风已打开，未静音，并设置为以 86 级捕获音频。

我认为默认设备未正确设置（使用 ALSA），因为当我这样做时：

arecord test.wav

和

aplay test.wav

没有任何记录。

Answer 1

想通了。看起来 Ubuntu 带有 PulseAudio 和 ALSA。 PulseAudio 正在劫持默认设备位置。

这有点“死板”，但我刚刚完全删除了 PulseAudio，问题就消失了。

sudo apt-get autoremove pulseaudio