Hello folks,
I use two USB 7.1 sound cards (C-Media chip CM6533 I think) on a Raspi 4. I
wanted to split the 8 channel sound cards to have 8 single stereo outputs.
For this I wanted to use the ALSA dshare plugin. My problem: I cannot use
two virtual sound cards from two different real sound cards at the same
time.
For better explanation here my asound.conf with a minimal configuration to
demonstrate my problem:
You can see two sound cards hw:1,0 and hw:2,0. Form card1 I created with
dshare stereo1 and from card2 I created stereo2.
pcm_slave.card1 {
pcm "hw:1,0"
channels 8
}
pcm.stereo1 {
type plug
slave.pcm {
type dshare
ipc_key 1111
slave card1
bindings.0 0
bindings.1 1
}
}
pcm_slave.card2{
pcm "hw:2,0"
channels 8
}
pcm.stereo2 {
type plug
slave.pcm {
type dshare
ipc_key 2222
slave card2
bindings.0 0
bindings.1 1
}
}
I cannot playback an audio file via aplay from stereo1 and stereo2 at the
same time. If I have started the playback from stereo1 and then want to
start the playback from stereo2 I get the following error:
pi@raspberrypi:~ $ aplay -Dplug:stereo2 /var/lib/mpd/music/example.mp3
ALSA lib pcm_direct.c:1271:(snd1_pcm_direct_initialize_slave) unable to
install hw params
ALSA lib pcm_dshare.c:778:(snd_pcm_dshare_open) unable to initialize slave
aplay: main:828: audio open error: Input/output error
Please can anyone help me. I have no clue how to solve this. Actually, this
setup worked before with an BeagleBoneBlack with an old Ubuntu. I have no
idea why this should not work with my Raspi 4.
Here is my output of alsa-info:
http://alsa-project.org/db/?f=754e988bd2b94cd4679060d1fa7d19c87b1d0077
Thanks in advance.
Best wishes,
Andreas
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