5 - Les serveurs son : JACK, PipeWire, PulseAudio et autres...

jeansef@sff:~$ cat /proc/asound/cards
 1 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xd4144000 irq 127
 2 [NVidia         ]: HDA-Intel - HDA NVidia
                      HDA NVidia at 0xd4000000 irq 17
 3 [XPRESSCAM1080FH]: USB-Audio - NGS XPRESSCAM1080FHD
                      BC-250217-XH NGS XPRESSCAM1080FHD at usb-0000:00:14.0-8, high speed
 4 [UMC1820        ]: USB-Audio - UMC1820
                      BEHRINGER UMC1820 at usb-0000:00:14.0-9, high speed
 7 [WEBCAM         ]: USB-Audio - C270 HD WEBCAM
                      C270 HD WEBCAM at usb-0000:00:14.0-10.2, high speed

jeansef@sff:~$ cat /etc/security/limits.d/audio.conf 
# Provided by the jackd package.
#
# Changes to this file will be preserved.
#
# If you want to enable/disable realtime permissions, run
#
#    dpkg-reconfigure -p high jackd2

@audio   -  rtprio     95
@audio   -  memlock    unlimited
#@audio   -  nice      -19

jeansef@sff:~$ uname -a
Linux sff 6.12.63+deb13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.63-1 (2025-12-30) x86_64 GNU/Linux

jeansef@sff:~/.config/pipewire/pipewire.conf.d$ cat 99-umc1820-routing.conf 
#création d'un module 'loopback' avec une description lisible:
context.modules = [
{ name = libpipewire-module-loopback
        args = {
            node.description = "OBS_Micro"
            capture.props = {
                node.name = "capture.obs_micro"
                target.object = "alsa_input.usb-BEHRINGER_UMC1820_BFAAEA29-00.pro-input-0"
                audio.position = [ AUX0 ] 
                stream.dont-remix = true
                node.passive = true
            }
            playback.props = {
                node.name = "obs_micro_input"
                media.class = "Audio/Source"
                audio.position = [ MONO ]
            }
        }
    }
#un autre pour la gratte
    { name = libpipewire-module-loopback
        args = {
            node.description = "OBS_Guitare"
            capture.props = {
                node.name = "capture.obs_guitare"
                target.object = "alsa_input.usb-BEHRINGER_UMC1820_BFAAEA29-00.pro-input-0"
                audio.position = [ AUX1 ]
                stream.dont-remix = true
                node.passive = true
            }
            playback.props = {
                node.name = "obs_guitare_input"
                media.class = "Audio/Source"
                audio.position = [ FL FR ]
            }
        }
    }
#un autre pour la batterie avec 6 micros
    { name = libpipewire-module-loopback
        args = {
            node.description = "OBS_Batterie_Mix"                                                                                                                                                                 
            capture.props = {                                                                                                                                                                                     
                node.name = "capture.obs_batterie"                                                                                                                                                                
                target.object = "alsa_input.usb-BEHRINGER_UMC1820_BFAAEA29-00.pro-input-0"                                                                                                                        
                audio.position = [ AUX2 AUX3 AUX4 AUX5 AUX6 AUX7 ]                                                                                                                                                
                stream.dont-remix = true                                                                                                                                                                          
                node.passive = true                                                                                                                                                                               
            }                                                                                                                                                                                                     
            playback.props = {                                                                                                                                                                                    
                node.name = "obs_batterie_input"                                                                                                                                                                  
                media.class = "Audio/Source"                                                                                                                                                                      
                audio.position = [ FL FR ]                                                                                                                                                                        
            }                                                                                                                                                                                                     
        }
    }
]
# la seule optimisation pour le moment:
context.properties = {
    default.clock.rate = 48000
    default.clock.quantum = 256
}