ALSA Output - only first Cue works

[tatrapikao]

Hi there,

I am trying to achieve the following:

4-Channel Wav playing its 4 Channels individually to 4 Outputs on a 4 Channel Interface (Behringer UCM404HD). As Jack and gstreamer are currently broken and Pulse (or Pipewire) tries hard to only deliver downmixed Stereo (no panner involved) i thought maybe using plain old ALSA would be the way. And it is - the File plays to the 4 Outputs. Yeah! Unfortunately this works only for the first Cue in the List. The Cues that are following are configured the same but drop the following error (even if the first cue in list is not playing):

lisp.plugins.gst_backend.gst_utils.GstError: ../ext/alsa/gstalsasink.c(884): gst_alsasink_open (): /GstPipeline:pipeline4/GstAlsaSink:sink:

Device 'surround40:CARD=U192k,DEV=0' is busy

This happens with the Flatpack version on fedora 43.

Any hint would be welcome.

[s0600204]

Hi,

External sound card devices, when operated with ALSA, typically run in exclusive mode, where the first application/utility that uses a channel on a sound card has exclusive use of that channel until it releases it (invariably by exiting). (This is how ALSA is written, not a failing in LiSP.)

Where LiSP doesn't make this any easier is that, due to how media cues work, each media cue is seen (by ALSA) as a different application.

To get round this, you will need to create an .asoundrc file in your user's home folder (if one doesn't already exist), and configure a virtual PCM device that uses dmix. Documentation can be found here: https://www.alsa-project.org/wiki/Asoundrc

And no, it's not straight forward. But that's ALSA for you, unfortunately.

And remember to give your virtual PCM device a name so it appears in the ALSA device selection dropdown within LiSP:

To make your custom PCM objects appear correctly in this list requires adding a 'hint.description' line to them.

[tatrapikao]

Hi, as the project was on hold for some time, this came to my desk again just today - as i wrote an .asoundrc file in home i get a working dmix plug that i can test and see via aplay. But under no cirumstances i can see it in LSP. I tried:

• putting config to ~/.asoundrc
• putting config in /etc/asound.conf
• reinstalling lsp
• rebooting
• yes - i put hint.description line in the config

this is it:

pcm.behringer {
type hw
card 0
device 0
}

ctl.behringer {
type hw
card 0
device 0
}

pcm.verfassung {
type plug
slave.pcm "dmixer"
hint.description "VERFASSUNG"
}

pcm.dmixer {
type dmix
ipc_key 1024
slave {
pcm "Behringer"
}
}

[tatrapikao]

hmm.. I gave up on this one and went and installed another distro.. Now everything works as intended with pipewire. Linuxmint seems to have a 4Channel Profile for the Behringer Soundcard that seems to be missing in fedora..