====== AUDIO, SON, CARTES-SON, ETC. ======


===== Loopback =====
Permettre d'écouter ce qui arrive depuis l'entrée micro ou ligne :
Pour PulseAudio
<code bash>
pactl load-module module-loopback
</code>

Charger le module //loopback// au démarrage
<code bash>
sudo sh -c ' echo "load-module module-loopback" >>  /etc/pulse/default.pa '
</code>

Pour ALSA...
<code bash>
sudo modprobe snd_aloop
</code>

<code bash>
# create/edit ~/.asoundrc and paste in the following (a bit of alsa black magic):

pcm.!default {
  type asym
  playback.pcm "LoopAndReal"
  #capture.pcm "looprec"
  capture.pcm "hw:0,0"
}

pcm.looprec {
    type hw
    card "Loopback"
    device 1
    subdevice 0
}

pcm.LoopAndReal {
  type plug
  slave.pcm mdev
  route_policy "duplicate"
}

pcm.mdev {
  type multi
  slaves.a.pcm pcm.MixReale
  slaves.a.channels 2
  slaves.b.pcm pcm.MixLoopback
  slaves.b.channels 2
  bindings.0.slave a
  bindings.0.channel 0
  bindings.1.slave a
  bindings.1.channel 1
  bindings.2.slave b
  bindings.2.channel 0
  bindings.3.slave b
  bindings.3.channel 1
}

pcm.MixReale {
  type dmix
  ipc_key 1024
  slave {
    pcm "hw:0,0"
    rate 48000
    #rate 44100
    periods 128
    period_time 0
    period_size 1024 # must be power of 2
    buffer_size 8192
  }
}

pcm.MixLoopback {
  type dmix
  ipc_key 1025
  slave {
    pcm "hw:Loopback,0,0"
    rate 48000
    #rate 44100
    periods 128
    period_time 0
    period_size 1024 # must be power of 2
    buffer_size 8192
  }
}
</code>

Ajouter à ''/etc/modprobe.d/alsa-base.conf''
<code bash>
options snd-aloop index=-2
</code>



===== Pas de /dev/dsp ? =====

<code bash>
Error: audio: /dev/dsp: No such file or directory
</code>

If the audio mixer application is reporting that no mixer is available, or gives an error:
<code bash>
audio: /dev/dsp: No such file or directory
</code>
It is necessary to load the ''snd-pcm-oss module''.


=== Créer /dev/dsp pour les applications ALSA qui écrivent directement vers le périph de sortie ===
<code bash>
padsp executable_name > /dev/dsp
</code>

===== STOCKER LES RÉGLAGES ALSAMIXER =====
<code bash>
$alsactl store
</code>