Amplifier la capture alsa au-delà de 100 % ?

Utiliser le module softvol, il est expliqué ici :

http://blog.tpa.me.uk/2013/10/23/alsa-pre-amp-volume-boost-the-simple-explanation/

# Set your DEFAULT device to the softvol plug-in
# NOT to a hardware card device
#
# The "!" means completely override the previous default
# Not just changing/adding to it.
pcm.!default {
  type plug
  slave.pcm "softvol"
}

# Configure softvol
pcm.softvol {
  type softvol

  # Send softvol's output to dmix
  slave {
    pcm "dmix"
    # If you wanted to you could send the output to a card directly
    # But in most cases it's better to send it to dmix and let
    # dmix handle where to send it. You can add a whole extra section
    # to configure dmix and where it sends output, but I'm
    # not covering that here.

    ## Use Card 0 Device 0 instead of dmix
    # pcm "hw:0,0"
    ## Use Card 2 Device 0 instead of dmix
    # pcm "hw:2,0"
  }

  # Add a control slider in your mixer interfaces
  # i.e. KMix and alsamixer
  control {
    name "Pre-Amp"
    card <CardNumberYouWantControlToShowOn>
    # i.e. card 0 or card 2
  }

  # Minimum dB when slider is at 0%
  min_dB -5.0

  # Maximum DB when slider is at 100%
  max_dB 40.0

  # How many levels the slider should go through
  # i.e. how granular do you want your control to be
  resolution 12
}