Re: How to map 2 channels from a 32-channel USB device to L/R?

[Richard Cooke <rcooke@xxxxxxxxxx>]

@Sean

I popped in to the church to get this info and try again with the analog output cable.

Just powered up the QU and rebooted my PC.  I am trying to email from an account I created for this pc.  If that bombs I will resend from my account.

So I did:

camera@cameras:~$ pactl list sources

And got:

Source #0
State: SUSPENDED
Name: alsa_output.usb-Allen_Heath_Ltd_QU-24-01.multichannel-output.monitor
Description: Monitor of QU-24 Multichannel
Driver: module-alsa-card.c
Sample Specification: s32le 32ch 48000Hz
Channel Map: front-left,front-right,rear-left,rear-right,front-center,lfe,side-left,side-right,aux0,aux1,aux2,aux3,aux4,aux5,aux6,aux7,aux8,aux9,aux10,aux11,aux12,aux13,aux14,aux15,aux16,aux17,aux18,aux19,aux20,aux21,aux22,aux23
Owner Module: 7
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB,   rear-left: 65536 / 100% / 0.00 dB,   rear-right: 65536 / 100% / 0.00 dB,   front-center: 65536 / 100% / 0.00 dB,   lfe: 65536 / 100% / 0.00 dB,   side-left: 65536 / 100% / 0.00 dB,   side-right: 65536 / 100% / 0.00 dB,   aux0: 65536 / 100% / 0.00 dB,   aux1: 65536 / 100% / 0.00 dB,   aux2: 65536 / 100% / 0.00 dB,   aux3: 65536 / 100% / 0.00 dB,   aux4: 65536 / 100% / 0.00 dB,   aux5: 65536 / 100% / 0.00 dB,   aux6: 65536 / 100% / 0.00 dB,   aux7: 65536 / 100% / 0.00 dB,   aux8: 65536 / 100% / 0.00 dB,   aux9: 65536 / 100% / 0.00 dB,   aux10: 65536 / 100% / 0.00 dB,   aux11: 65536 / 100% / 0.00 dB,   aux12: 65536 / 100% / 0.00 dB,   aux13: 65536 / 100% / 0.00 dB,   aux14: 65536 / 100% / 0.00 dB,   aux15: 65536 / 100% / 0.00 dB,   aux16: 65536 / 100% / 0.00 dB,   aux17: 65536 / 100% / 0.00 dB,   aux18: 65536 / 100% / 0.00 dB,   aux19: 65536 / 100% / 0.00 dB,   aux20: 65536 / 100% / 0.00 dB,   aux21: 65536 / 100% / 0.00 dB,   aux22: 65536 / 100% / 0.00 dB,   aux23: 65536 / 100% / 0.00 dB
       balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor of Sink: alsa_output.usb-Allen_Heath_Ltd_QU-24-01.multichannel-output
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY 
Properties:
device.description = "Monitor of QU-24 Multichannel"
device.class = "monitor"
alsa.card = "1"
alsa.card_name = "QU-24"
alsa.long_card_name = "Allen&Heath Ltd QU-24 at usb-0000:00:14.0-2.4, high speed"
alsa.driver_name = "snd_usb_audio"
device.bus_path = "pci-0000:00:14.0-usb-0:2.4:1.1"
sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb1/1-2/1-2.4/1-2.4:1.1/sound/card1"
udev.id = "usb-Allen_Heath_Ltd_QU-24-01"
device.bus = "usb"
device.vendor.id = "22f0"
device.vendor.name = "Allen&Heath Ltd"
device.product.id = "0007"
device.product.name = "QU-24"
device.serial = "Allen_Heath_Ltd_QU-24"
device.string = "1"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card-usb"
Formats:
pcm

Source #1
State: SUSPENDED
Name: alsa_input.usb-Allen_Heath_Ltd_QU-24-01.multichannel-input
Description: QU-24 Multichannel
Driver: module-alsa-card.c
Sample Specification: s32le 32ch 48000Hz
Channel Map: front-left,front-right,rear-left,rear-right,front-center,lfe,side-left,side-right,aux0,aux1,aux2,aux3,aux4,aux5,aux6,aux7,aux8,aux9,aux10,aux11,aux12,aux13,aux14,aux15,aux16,aux17,aux18,aux19,aux20,aux21,aux22,aux23
Owner Module: 7
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB,   rear-left: 65536 / 100% / 0.00 dB,   rear-right: 65536 / 100% / 0.00 dB,   front-center: 65536 / 100% / 0.00 dB,   lfe: 65536 / 100% / 0.00 dB,   side-left: 65536 / 100% / 0.00 dB,   side-right: 65536 / 100% / 0.00 dB,   aux0: 65536 / 100% / 0.00 dB,   aux1: 65536 / 100% / 0.00 dB,   aux2: 65536 / 100% / 0.00 dB,   aux3: 65536 / 100% / 0.00 dB,   aux4: 65536 / 100% / 0.00 dB,   aux5: 65536 / 100% / 0.00 dB,   aux6: 65536 / 100% / 0.00 dB,   aux7: 65536 / 100% / 0.00 dB,   aux8: 65536 / 100% / 0.00 dB,   aux9: 65536 / 100% / 0.00 dB,   aux10: 65536 / 100% / 0.00 dB,   aux11: 65536 / 100% / 0.00 dB,   aux12: 65536 / 100% / 0.00 dB,   aux13: 65536 / 100% / 0.00 dB,   aux14: 65536 / 100% / 0.00 dB,   aux15: 65536 / 100% / 0.00 dB,   aux16: 65536 / 100% / 0.00 dB,   aux17: 65536 / 100% / 0.00 dB,   aux18: 65536 / 100% / 0.00 dB,   aux19: 65536 / 100% / 0.00 dB,   aux20: 65536 / 100% / 0.00 dB,   aux21: 65536 / 100% / 0.00 dB,   aux22: 65536 / 100% / 0.00 dB,   aux23: 65536 / 100% / 0.00 dB
       balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor of Sink: n/a
Latency: 0 usec, configured 0 usec
Flags: HARDWARE DECIBEL_VOLUME LATENCY 
Properties:
alsa.resolution_bits = "32"
device.api = "alsa"
device.class = "sound"
alsa.class = "generic"
alsa.subclass = "generic-mix"
alsa.name = "USB Audio"
alsa.id = "USB Audio"
alsa.subdevice = "0"
alsa.subdevice_name = "subdevice #0"
alsa.device = "0"
alsa.card = "1"
alsa.card_name = "QU-24"
alsa.long_card_name = "Allen&Heath Ltd QU-24 at usb-0000:00:14.0-2.4, high speed"
alsa.driver_name = "snd_usb_audio"
device.bus_path = "pci-0000:00:14.0-usb-0:2.4:1.1"
sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb1/1-2/1-2.4/1-2.4:1.1/sound/card1"
udev.id = "usb-Allen_Heath_Ltd_QU-24-01"
device.bus = "usb"
device.vendor.id = "22f0"
device.vendor.name = "Allen&Heath Ltd"
device.product.id = "0007"
device.product.name = "QU-24"
device.serial = "Allen_Heath_Ltd_QU-24"
device.string = "hw:1"
device.buffering.buffer_size = "1048576"
device.buffering.fragment_size = "524288"
device.access_mode = "mmap+timer"
device.profile.name = "multichannel-input"
device.profile.description = "Multichannel"
device.description = "QU-24 Multichannel"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card-usb"
Ports:
multichannel-input: Multichannel Input (priority: 0)
Active Port: multichannel-input
Formats:
pcm

Source #2
State: SUSPENDED
Name: alsa_output.pci-0000_00_1f.3.analog-stereo.monitor
Description: Monitor of Built-in Audio Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s32le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 8
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB
       balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor of Sink: alsa_output.pci-0000_00_1f.3.analog-stereo
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY 
Properties:
device.description = "Monitor of Built-in Audio Analog Stereo"
device.class = "monitor"
alsa.card = "0"
alsa.card_name = "HDA Intel PCH"
alsa.long_card_name = "HDA Intel PCH at 0xf7320000 irq 130"
alsa.driver_name = "snd_hda_intel"
device.bus_path = "pci-0000:00:1f.3"
sysfs.path = "/devices/pci0000:00/0000:00:1f.3/sound/card0"
device.bus = "pci"
device.vendor.id = "8086"
device.vendor.name = "Intel Corporation"
device.product.id = "a2f0"
device.product.name = "200 Series PCH HD Audio"
device.form_factor = "internal"
device.string = "0"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card-pci"
Formats:
pcm

Source #3
State: SUSPENDED
Name: alsa_input.pci-0000_00_1f.3.analog-stereo
Description: Built-in Audio Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s32le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 8
Mute: no
Volume: front-left: 17948 /  27% / -33.75 dB,   front-right: 17948 /  27% / -33.75 dB
       balance 0.00
Base Volume: 6554 /  10% / -60.00 dB
Monitor of Sink: n/a
Latency: 0 usec, configured 0 usec
Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY 
Properties:
alsa.resolution_bits = "32"
device.api = "alsa"
device.class = "sound"
alsa.class = "generic"
alsa.subclass = "generic-mix"
alsa.name = "ALC662 rev3 Analog"
alsa.id = "ALC662 rev3 Analog"
alsa.subdevice = "0"
alsa.subdevice_name = "subdevice #0"
alsa.device = "0"
alsa.card = "0"
alsa.card_name = "HDA Intel PCH"
alsa.long_card_name = "HDA Intel PCH at 0xf7320000 irq 130"
alsa.driver_name = "snd_hda_intel"
device.bus_path = "pci-0000:00:1f.3"
sysfs.path = "/devices/pci0000:00/0000:00:1f.3/sound/card0"
device.bus = "pci"
device.vendor.id = "8086"
device.vendor.name = "Intel Corporation"
device.product.id = "a2f0"
device.product.name = "200 Series PCH HD Audio"
device.form_factor = "internal"
device.string = "front:0"
device.buffering.buffer_size = "705600"
device.buffering.fragment_size = "352800"
device.access_mode = "mmap+timer"
device.profile.name = "analog-stereo"
device.profile.description = "Analog Stereo"
device.description = "Built-in Audio Analog Stereo"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card-pci"
Ports:
analog-input-front-mic: Front Microphone (priority: 8500, available)
analog-input-rear-mic: Rear Microphone (priority: 8200, not available)
analog-input-linein: Line In (priority: 8100, not available)
Active Port: analog-input-front-mic
Formats:
pcm

Source #4
State: IDLE
Name: Source.monitor
Description: Monitor of Null Output
Driver: module-null-sink.c
Sample Specification: float32le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 26
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB
       balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor of Sink: Source
Latency: 0 usec, configured 2000000 usec
Flags: DECIBEL_VOLUME LATENCY 
Properties:
device.description = "Monitor of Null Output"
device.class = "monitor"
device.icon_name = "audio-input-microphone"
Formats:
pcm

Source #5
State: SUSPENDED
Name: VirtualMic
Description: Virtual Source VirtualMic on Monitor of Null Output
Driver: module-virtual-source.c
Sample Specification: float32le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 27
Mute: no
Volume: front-left: 65536 / 100%,   front-right: 65536 / 100%
       balance 0.00
Base Volume: 65536 / 100%
Monitor of Sink: n/a
Latency: 0 usec, configured 0 usec
Flags: HW_MUTE_CTRL LATENCY 
Properties:
device.master_device = "Source.monitor"
device.class = "filter"
device.vsource.name = "VirtualMic"
device.description = "Virtual Source VirtualMic on Monitor of Null Output"
device.icon_name = "audio-input-microphone"
Formats:
pcm

Richard Cooke

(Sent from my iPhone)

On Jul 11, 2022, at 3:25 AM, Sean Greenslade <sean@xxxxxxxxxxxxxxxxxx> wrote:

On Sun, Jul 10, 2022 at 09:41:16PM -0400, Richard Cooke wrote:

On 2022-07-10 4:14 PM, Sean Greenslade wrote:

You should (in theory) be able to use module-remap-sink or

module-remap-source to create a virtual 2-channel sink/source using

specific channels from the 32 channel one. See:

https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/Modules/#module-remap-sink

It may require some experimentation to figure out what names pulse is

assigning to each channel, since the first 8 channels are given

standardized 7.1-channel names. Take a look here for the string names

that module-remap-* is looking for in channel_map:

https://github.com/pulseaudio/pulseaudio/blob/7f4d7fcf5f6407913e50604c6195d0d5356195b1/src/pulse/channelmap.c#L39

Thanks Sean!  I was working on it again today, I posted the latest update to

another website:

https://linuxmusicians.com/viewtopic.php?f=27&t=24713&sid=e80ee72d0f2e1b23402e32e62ca0bf6f

In summary, I can see only two MIDI devices in the signal patch window.  I

do not see the 32-channels of audio data that I know is there - because

Audacity can access it.

So I assume I am missing something in my config to expose those channels.

I'll read through your links too, in  case the missing piece is in there.

Part of my frustration is I can only see the QU when its powered up.  The

streaming PC is on all the time, but we cannot leave the QU powered up

because of the main power amps.  Bad things could easily happen if I play

around with signals while the whole system is live!  Or while left

unattended.

I re-added the mailing list, although this is perhapes straying away
from a pulse-specific discussion.

You mention "Catlia" in your forum post, which I assume is a typo. There
are two similar programs in the KXStudio lineup, "Catia" and "Carla".
I'm assuming you're using catia, which is a patchbay for the JACK audio
server. JACK is similar to Pulseaudio in that it is a sound routing
engine and not a direct soundcard driver. In Linux, the soundcard driver
is ALSA. Both JACK and Pulse make use of ALSA to interact with the
hardware sound devices. Generally speaking you would only use one sound
server. Although there are ways to run both simultaneously and to route
audio between the two, that's definitely an advanced setup.

Note that Catia cannot control Pulseaudio at all, and while Carla
technically has the ability to use Pulse as its backend, it doesn't
expose the Pulse sources / sinks in a useful way to provide the type of
routing you're looking to do.

From your screenshot, it appears that JACK has not taken control of the
ALSA device for your 32-channel mixer, or it's not configured correctly
to detect and expose the full channel count. You should probably find a
JACK mailing list if you want to go down that route, although I believe
Pulse is fully capable of accomplishing the task you laid out in your
original email.

One side note: MIDI is not the same as audio. If you're only concerned
about routing audio signals around, you can completely ignore MIDI.

To give some more concrete suggestions, can you do a fresh reboot of the
streaming PC, turn on and connect the mixer, then run the following
command and post its output:

$ pactl list sources

--Sean