Quel Pilote graphique utilises tu ?
Comment est il installé ? Es tu en x86_66 ?

Que donne ProjectM ou le lecteur l'utilisant lancé en ligne de commande ?
je suis en x86_64 et je ne connai pas de lecteur qui utilise projectM.
J'utilise projectM-pulseaudio et selon le contrôle de volume ProjectM reçois bien du son.
[jeremy2491@jeremy2491 ~]$ projectM-pulseaudio
dir:/usr/share/projectM/config.inp 
reading ~/.projectM/config.inp 
configFile: /home/jeremy2491/.projectM/config.inp
MAX SAMPLES:2048
load config END 
device name is  "alsa_output.pci_8086_293e_sound_card_0.monitor" 
reconnecting with "alsa_output.pci_8086_293e_sound_card_0.monitor" 
unconnected: connecting... 
connectHelper:  "alsa_output.pci_8086_293e_sound_card_0.monitor"
/home/jeremy2491/.projectM/config.inp 
Aspect Correction = 1
Easter Egg Parameter = 1
FPS = 35
Fullscreen = false
Hard Cut Sensitivity = 10
Menu Font = /usr/share/projectM/fonts/VeraMono.ttf
Mesh X = 32
Mesh Y = 24
Preset Duration = 30
Preset Path = /usr/share/projectM/presets
Shuffle Enabled = 1
Smooth Preset Duration = 5
Smooth Transition Duration = 5
Texture Size = 1024
Title Font = /usr/share/projectM/fonts/Vera.ttf
Window Height = 512
Window Width = 512
n = 5  # in seconds
Preset Duration = 30              # in seconds
Easter Egg Parameter = 1

Hard Cut Sensitivity = 10       # Lower to make hard cuts more frequent
Aspect Correction = true    # Custom Shape Aspect Correction

Preset Path = /usr/share/projectM/presets # preset location
Title Font = /usr/share/projectM/fonts/Vera.ttf
Menu Font = /usr/share/projectM/fonts/VeraMono.ttf
vlc 1.1.x devrait utiliser project-M mais c'est dans la branche instalble de vlc...