Can't get audio loopback devices to create?

1

Trying to install the audio loopback devices on Raspberry Pi 400 running the latest Raspberry Pi OS “bullseye”. Followed the instructions, and can’t seem to get the loopback devices created or initialized or something.

On boot, I get the error:
snd_aloop snd_aloop.0: cannot find the slot for index 10 (range 0-0) error: -19
snd_aloop snd_aloop.1: cannot find the slot for index 11 (range 0-0) error: -19
aloop: No loopback enabled

I thought perhaps there was a conflict with the existing hdmi sound card (I have a television as a display), so I also tried calling it snd-card-2 instead of snd-card-0 for the alias:
alias snd-card-2 snd-aloop
options snd-aloop enable=1,1 index=10,11

(as shown in the documentation).

k0in@raspberrypi:/ $ sudo modprobe snd-aloop
modprobe: ERROR: could not insert ‘snd_aloop’: No such device
k0in@raspberrypi:/ $ cat /proc/asound/cards
0 [vc4hdmi0 ]: vc4-hdmi - vc4-hdmi-0
vc4-hdmi-0
1 [vc4hdmi1 ]: vc4-hdmi - vc4-hdmi-1
vc4-hdmi-1

Any wisdom would be appreciated.

2

I’ve solved this issue by using index=0,1 instead of index=10,11

Still working through other issues.

This is fun, right?

1 Like
3

I get this error, too, but the workaround (index = 0,1) didn’t work for me. I get this error in dmesg:

[ 20.275656] snd_aloop snd_aloop.0: cannot find the slot for index 0 (range 0-3), error: -16
[ 20.275679] snd_aloop: probe of snd_aloop.0 failed with error -16
[ 20.275911] snd_aloop snd_aloop.1: cannot find the slot for index 1 (range 0-3), error: -16
[ 20.275922] snd_aloop: probe of snd_aloop.1 failed with error -16
[ 20.275983] aloop: No loopback enabled

Any suggestions?

Thanks.

Chris W6COV

4

Hi Chris,

Can you try this solution mentioned here:

I think if you increase the “limit” then you can add higher-number slot loopback devices. I can’t replicate the issue here, and I use 10 and 11 for mine.

–E
de W6EL

5

I tried this for /etc/modprobe.d/virtual-sound.conf:

alias snd-card-0 snd-aloop
options snd cards_limit=9
options snd-aloop enable=1,1 index=7,8

index 10,11 gave me errors. This gives me fewer errors, but I see this in dmesg:

[ 22.119288] snd_aloop snd_aloop.1: unable to register control minors

Any suggestions?

Thanks.

Chris W6COV