USB is not working properly (playback and record are too loud?)

Question

I recently bought a cheap a USB Audio card and I have some issues with it.

It records audio so awful. Apparently the volume of the mic in is so loud and distorts. I figured out this in alsamixer. The input or output volumes assigned to this device cannot be changed.

My USB Audio card is listed by lsusb:

CODE: SELECT ALL
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
Bus 001 Device 004: ID 1130:f211 Tenx Technology, Inc. TP6911 Audio Headset

Another problem is that the recorded audio plays a little fast, maybe the sampling rate is also wrong.

Answer 1

There is a good tutorial on the ALSA website. Basically it boils down to this:

1. Add a soft volume device to your ~/.asoundrc:

   pcm.softvol {
       type            softvol
       slave {
           pcm         "<device name>"
       }
       control {
           name        "SoftMaster"
           card        0
       }
   }
   

   Instead of <device name>, you should put your PCM device there. You can list all devices by typing aplay -L. Then pick your headset as the slave device.

2. Add the new device as your default device in ~/.asoundrc:

   pcm.!default {
       type             plug
       slave.pcm       "softvol"
   }
   

I haven't tried this, but I think these are the most important steps from the above tutorial. In your case, I would also use dmix as well, but that is described in the tutorial in more detail. Hopefully, the above lines will get you started.

Answer 2

Have you tried using your microphone with Pulseaudio? Alsa is very much a tool of the past ( although it is still needed at times, especially w/ some of the microphones that are on the market these days ). Pulseaudio often takes care of a lot of the quality issues that are associated with microphone devices, and offers a number of really awesome features.

Basic installation steps below ( See my link at the end of this answer for more specific notes if you're trying to obtain the same configuration that I have on my RaspberryPi):

Install pulse audio / development packages

sudo apt-get install gstreamer0.10-pulseaudio libao4 libasound2-plugins libgconfmm-2.6-1c2 libglademm-2.4-1c2a libpulse-dev libpulse-mainloop-glib0 libpulse-mainloop-glib0-dbg libpulse0 libpulse0-dbg libsox-fmt-pulse paman paprefs pavucontrol pavumeter pulseaudio pulseaudio-dbg pulseaudio-esound-compat pulseaudio-esound-compat-dbg pulseaudio-module-bluetooth pulseaudio-module-gconf pulseaudio-module-jack pulseaudio-module-lirc pulseaudio-module-lirc-dbg pulseaudio-module-x11 pulseaudio-module-zeroconf pulseaudio-module-zeroconf-dbg pulseaudio-utils oss-compat -y

Change alsa to use pulse:

sudo \cp -pf /etc/asound.conf /etc/asound.conf.ORIG 
echo 'pcm.pulse {
    type pulse
}

ctl.pulse {
    type pulse
}

pcm.!default {
    type pulse
}

ctl.!default {
    type pulse
}' | sudo tee /etc/asound.conf

Make sure your camera device loads on boot:

# Disallow module loading after startup. This is a security feature since it disallows additional module loading during runtime and on user request.
_DISALLOW_MODULE_LOADING=$(grep "DISALLOW_MODULE_LOADING=1" /etc/default/pulseaudio | wc -l)
if [[ "${_DISALLOW_MODULE_LOADING}" = "0" ]]; then

  sudo \cp -pf /etc/default/pulseaudio /etc/default/pulseaudio.ORIG
  sudo sed -i "s,DISALLOW_MODULE_LOADING=1,DISALLOW_MODULE_LOADING=0,g" /etc/default/pulseaudio

fi

Prevent PulseAudio from sending the audio hardware to sleep.

# This is the important part that prevents PulseAudio from sending the audio hardware to sleep. 
sudo sed -i 's,#load-module module-suspend-on-idle,load-module module-suspend-on-idle,g' /etc/pulse/default.pa

Optimize the pulse audio daemon config:

sudo \cp -fvp /etc/pulse/daemon.conf /etc/pulse/daemon.conf.${_DATE}

echo "
# ScarlettPi added this
high-priority = yes
nice-level = 5
exit-idle-time = -1
resample-method = src-sinc-medium-quality
default-sample-format = s16le
default-sample-rate = 48000
default-sample-channels = 2" | sudo tee -a /etc/pulse/daemon.conf

Add your user to the pulse-access group. In my case, my user is pi.

# add pi user to audio groups
sudo adduser pi pulse-access

Reboot:

sudo shutdown -r now

When the system is up and running, make sure pulse audio is started:

/usr/bin/pulseaudio --start --log-target=syslog --log-level=debug --system=false

Now see if everything works!

Hope this helps you. If you need any more help troubleshooting just comment on answer and @ me.

More reading here: