[alsa-devel] how to link multi plugin to dsnoop ?

Vincent Meserette vmeserette at aldebaran-robotics.com
Wed May 11 15:35:39 CEST 2011

Hi all,

I would like to allow multiple applications to access the audio inputs and
outputs of my system at same time.
I succeded to make it for the audio outputs by using the dmix plugin, but I
don't know how to do it with the dsnoop plugin because it seems I cannot
link directly the multi plugin to dsnoop.
Here is the error message I have with the /etc/asound.conf file presented
below :

arecord -D"alduplex" -c4 -r48000 -fS16_LE /tmp/test.wav
ALSA lib pcm_direct.c:1490:(_snd_pcm_direct_get_slave_ipc_offset) Invalid
type 'multi' for slave PCM
arecord: main:654: audio open error: Invalid argument

Does someone know how can I route the multi plugin to dsnoop ?

Thanks in advance

My /etc/asound.conf file :

#output device
    type hw
    card 0

    type dmix
     ipc_key 1024
    ipc_perm 0666
        pcm AD1989A_outputs


#input device
pcm.4channelsDeinterleaved {
        type multi

        slaves.a.pcm "hw:0,0,0"
        slaves.a.channels 2
        slaves.b.pcm "hw:0,0,2"
        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.AD1989A_inputs {
        type route
        slave.pcm "4channelsDeinterleaved"
        ttable.0.0 1
        ttable.1.1 1
        ttable.2.2 1
        ttable.3.3 1

#4 channels dsnoop (plug-in for capture)
    type dsnoop
    ipc_key 1025
        ipc_perm 0666
        pcm AD1989A_inputs
        rate 48000
        channels 4


pcm.alduplex {
    type asym
    capture.pcm "aldsnoop"
    playback.pcm "aldmix"

### CTL DEVICES (controls)
ctl.mixer0 {
    type hw
    card 0

More information about the Alsa-devel mailing list