title: alsa cannot read control invalid argument - raspberry pi
body: <p>I am trying to record audio with the PS Eye on a raspberry pi model b plus (I have tried with older b models and the same issue occurs as below).</p>
  
  <p>I am able to record, and playback the recording with arecord/aplay so the mic is working. However, I want to increase the mic volume as the recording is very low.</p>
  
  <p>When I attempt this in alsamixer, it exits with the following error when I use F6 to change to the PS Eye soundcard:</p>
  
  <pre><code>cannot load mixer controls: Invalid argument
  </code></pre>
  
  <p>I also notice that the alsa-utils service will fail when the PS Eye is plugged in (fine otherwise):</p>
  
  <pre><code>sudo service alsa-utils restart
  [FAIL] Shutting down ALSA...warning: 'alsactl store' failed with error message 'alsactl: get_control:259: Cannot read control '2,0,0,Mic Capture Volume,0': Invalid argument'...failed.
  [....] Setting up ALSA...warning: 'alsactl restore' failed with error message 'No state is present for card CameraB409241
  Found hardware: "USB-Audio" "USB Mixer" "USB1415:2000" "" ""
  Hardware is initialized using a generic method
  No state is present for card CameraB409241'...amixer: Mixer hw:1 load error: Invalid argument
  amixer: Mixer hw:1 load error: Invalid argument
  amixer: Mixer hw:1 load error: Invalid argument
  amixer: Mixer hw:1 load error: Invalid argument
  amixer: Mixer hw:1 load error: Invalid argument
  ...
  done.
  </code></pre>
  
  <p>The problem seems to be the controls definition of the PS Eye. I would like to know the following:</p>
  
  <ol>
  <li><p>Where does alsamixer load the controls for a particular device from? Are they in the driver?</p></li>
  <li><p>Is there a way to increase the mic volume another way?</p></li>
  </ol>
  
  <p>I am not using Pulseaudio yet but will try it if I can't fix this in alsa.</p>
  
  <p>thanks</p>
  
  <p>Sytem logs:
  Without pulseaudio installed, neither restarting alsa or trying to open the controls in alsamixer produce anything in the system log. If pulse audio is installed however, trying to open the controls in alsamixer gives:</p>
  
  <pre><code>Oct 30 10:21:26 signaler pulseaudio[19000]: [pulseaudio] alsa-util.c: Unable to load mixer: Invalid argument
  Oct 30 10:21:27 signaler pulseaudio[19000]: [pulseaudio] server-lookup.c: Unable to contact D-Bus: org.freedesktop.DBus.Error.NotSupported: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
  Oct 30 10:21:27 signaler pulseaudio[19000]: [pulseaudio] main.c: Unable to contact D-Bus: org.freedesktop.DBus.Error.NotSupported: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
  </code></pre>