I want to run four identical USB audio devices, but ALSA shows only two of them on one machine (all four operate properly when plugged in alone).
It seems they are detected (and initialised) properly:
cat /proc/asound/modules
0 snd_usb_audio
1 snd_usb_audio
2 snd_usb_audio
3 snd_usb_audio
cat /proc/asound/cards
0 [Device ]: USB-Audio - USB PnP Sound Device
C-Media Electronics Inc. USB PnP Sound Device at usb-0000:00:12.2-3.1, full spe
1 [Device_1 ]: USB-Audio - USB PnP Sound Device
C-Media Electronics Inc. USB PnP Sound Device at usb-0000:00:12.2-3.2, full spe
2 [Device_2 ]: USB-Audio - USB PnP Sound Device
C-Media Electronics Inc. USB PnP Sound Device at usb-0000:00:12.2-3.3, full spe
3 [Device_3 ]: USB-Audio - USB PnP Sound Device
C-Media Electronics Inc. USB PnP Sound Device at usb-0000:00:12.2-3.4, full spe
cat /proc/asound/devices
0: [ 0] : control
16: [ 0- 0]: digital audio playback
24: [ 0- 0]: digital audio capture
32: [ 1] : control
33: : timer
48: [ 1- 0]: digital audio playback
56: [ 1- 0]: digital audio capture
64: [ 2] : control
80: [ 2- 0]: digital audio playback
88: [ 2- 0]: digital audio capture
96: [ 3] : control
112: [ 3- 0]: digital audio playback
120: [ 3- 0]: digital audio capture
aplay however shows only two of them.
./aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Device_1 [USB PnP Sound Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
What could be the limiting factor here?
controlCx
devices in/dev/snd/
? When you runstrace -e open aplay -l
, do all four get opened?