jackd/alsa: only 2 channels of 4 found on usb-interface Lexicon Omega (ALSA: cannot set channel count to 4 for capture)

Hi,

it isn't easy to describe but i will try and give you all information
which seem to interfer with the bug ..

Sorry, my system is running with german language output.

First my environment :

Description: Ubuntu 18.04.5 LTS
Release: 18.04

Kernel:
5.4.0-54-generic #60~18.04.1-Ubuntu SMP Fri Nov 6 17:25:16 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

alsa:
$ apt list --installed|grep -i alsa
alsa-base/bionic,bionic,now 1.0.25+dfsg-0ubuntu5 all [installiert]
alsa-utils/bionic,now 1.1.3-1ubuntu1 amd64 [installiert]
libsox-fmt-alsa/bionic-updates,bionic-security,now 14.4.2-3ubuntu0.18.04.1 amd64 [Installiert,automatisch]
libzita-alsa-pcmi0/bionic,now 0.2.0-4ubuntu2 amd64 [Installiert,automatisch]

jackd:
apt list --installed|grep -i jackd
jackd/bionic,bionic,now 5 all [Installiert,automatisch]
jackd2/bionic,now 1.9.12~dfsg-2 amd64 [Installiert,automatisch]
libjack-jackd2-0/bionic,now 1.9.12~dfsg-2 amd64 [Installiert,automatisch]
libjack-jackd2-dev/bionic,now 1.9.12~dfsg-2 amd64 [installiert]

My interface (Omega) :
$ aplay -l
**** Liste der Hardware-Geräte (PLAYBACK) ****
Karte 0: PCH [HDA Intel PCH], Gerät 0: ALC887-VD Analog [ALC887-VD Analog]
  Sub-Geräte: 1/1
  Sub-Gerät #0: subdevice #0
Karte 0: PCH [HDA Intel PCH], Gerät 1: ALC887-VD Digital [ALC887-VD Digital]
  Sub-Geräte: 1/1
  Sub-Gerät #0: subdevice #0
Karte 0: PCH [HDA Intel PCH], Gerät 3: HDMI 0 [HDMI 0]
  Sub-Geräte: 1/1
  Sub-Gerät #0: subdevice #0
Karte 0: PCH [HDA Intel PCH], Gerät 7: HDMI 1 [HDMI 1]
  Sub-Geräte: 1/1
  Sub-Gerät #0: subdevice #0
Karte 1: Omega [Lexicon Omega], Gerät 0: USB Audio [USB Audio]
  Sub-Geräte: 1/1
  Sub-Gerät #0: subdevice #0
Karte 1: Omega [Lexicon Omega], Gerät 1: USB Audio [USB Audio #1]
  Sub-Geräte: 1/1
  Sub-Gerät #0: subdevice #0

The problem:

I try to record some audio, using the usb-audio-interface Lexicon Omega.

This interface has 4 capture channels, but all efforts to get them working/configured failed.

Here is the commandline wich is working (but only two capture-channels !)

$ /usr/bin/jackd -T -ndefault -dalsa -r4800 -p256 -n3 H -D -d hw:Omega -i2 -o2
jackdmp 1.9.12
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2016 Grame.
Copyright 2016-2017 Filipe Coelho.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in realtime mode with priority 10
self-connect-mode is "Don't restrict self connect requests"
audio_reservation_init
Acquire audio card Audio1
creating alsa driver ... hw:Omega|hw:Omega|256|3|4800|2|2|nomon|swmeter|-|32bit
configuring for 4800Hz, period = 256 frames (53.3 ms), buffer = 3 periods
ALSA: final selected sample format for capture: 24bit little-endian in 3bytes format
ALSA: use 3 periods for capture
ALSA: final selected sample format for playback: 24bit little-endian in 3bytes format
ALSA: use 3 periods for playback

The same with 4 capture-channels fails:

$ /usr/bin/jackd -T -ndefault -dalsa -r4800 -p256 -n3 H -D -d hw:Omega -i4 -o2
jackdmp 1.9.12
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2016 Grame.
Copyright 2016-2017 Filipe Coelho.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in realtime mode with priority 10
self-connect-mode is "Don't restrict self connect requests"
audio_reservation_init
Acquire audio card Audio1
creating alsa driver ... hw:Omega|hw:Omega|256|3|4800|4|2|nomon|swmeter|-|32bit
configuring for 4800Hz, period = 256 frames (53.3 ms), buffer = 3 periods
ALSA: final selected sample format for capture: 24bit little-endian in 3bytes format
ALSA: cannot set channel count to 4 for capture
ALSA: cannot configure capture channel
JackTemporaryException : now quits...
Released audio card Audio1
audio_reservation_finish
Cannot initialize driver
JackServer::Open failed with -1
Failed to open server

So, one could say the interface is broken, but i tested on an older system (Ubuntustudio 16.04):

$ uname -a
4.10.0-42-lowlatency #46~16.04.1-Ubuntu SMP PREEMPT Mon Dec 4 17:13:40 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

$ apt list --installed|grep -i alsa
alsa-base/bionic,bionic,now 1.0.25+dfsg-0ubuntu5 all [installiert]
alsa-tools/bionic,now 1.1.3-1 amd64 [installiert]
alsa-tools-gui/bionic,now 1.1.3-1 amd64 [installiert]
alsa-utils/bionic,now 1.1.3-1ubuntu1 amd64 [installiert]
gstreamer1.0-alsa/bionic-updates,now 1.14.5-0ubuntu1~18.04.1 amd64 [installiert]
libsox-fmt-alsa/bionic-updates,bionic-security,now 14.4.2-3ubuntu0.18.04.1 amd64 [installiert]
libzita-alsa-pcmi0/bionic,now 0.2.0-4ubuntu2 amd64 [installiert]

$ apt list --installed|grep -i jackd
jackd/bionic,bionic,now 5 all [installiert]
jackd2/bionic,now 1.9.12~dfsg-2 amd64 [installiert]
jackd2-firewire/bionic,now 1.9.12~dfsg-2 amd64 [installiert]
libjack-jackd2-0/bionic,now 1.9.12~dfsg-2 amd64 [installiert]
libjack-jackd2-dev/bionic,now 1.9.12~dfsg-2 amd64 [installiert]

jackd is configure via qjackctl, no specification of channelcount (only default-value:0 ).

Here's the output of jackd starting (finding 4 capture channels + 2 playback channels)

--- snip---
Tue Nov 17 12:23:43 2020: Starting jack server...

Tue Nov 17 12:23:43 2020: JACK server starting in realtime mode with priority 10

Tue Nov 17 12:23:43 2020: self-connect-mode is "Don't restrict self connect requests"

Tue Nov 17 12:23:43 2020: Jack: JackPosixThread::StartImp : create non RT thread

Tue Nov 17 12:23:43 2020: Jack: JackPosixThread::ThreadHandler : start

Tue Nov 17 12:23:43 2020: Jack: capture device hw:Omega

Tue Nov 17 12:23:43 2020: Jack: playback device hw:Omega

Tue Nov 17 12:23:43 2020: Jack: apparent rate = 44100

Tue Nov 17 12:23:43 2020: Jack: frames per period = 256

Tue Nov 17 12:23:43 2020: Jack: JackDriver::Open capture_driver_name = hw:Omega

Tue Nov 17 12:23:43 2020: Jack: JackDriver::Open playback_driver_name = hw:Omega

Tue Nov 17 12:23:43 2020: Jack: Check protocol client = 8 server = 8

Tue Nov 17 12:23:43 2020: Jack: JackEngine::ClientInternalOpen: name = system

Tue Nov 17 12:23:43 2020: Jack: JackEngine::AllocateRefNum ref = 0

Tue Nov 17 12:23:43 2020: Jack: JackLinuxFutex::Allocate name = jack_sem.505_default_system val = 0

Tue Nov 17 12:23:43 2020: Jack: JackEngine::NotifyAddClient: name = system

Tue Nov 17 12:23:43 2020: Jack: JackGraphManager::SetBufferSize size = 256

Tue Nov 17 12:23:43 2020: Jack: JackConnectionManager::DirectConnect first: ref1 = 0 ref2 = 0

Tue Nov 17 12:23:43 2020: Jack: JackGraphManager::ConnectRefNum cur_index = 0 ref1 = 0 ref2 = 0

Tue Nov 17 12:23:43 2020: Jack: JackDriver::SetupDriverSync driver sem in flush mode

Tue Nov 17 12:23:43 2020: Acquired audio card Audio1

Tue Nov 17 12:23:43 2020: creating alsa driver ... hw:Omega|hw:Omega|256|2|44100|0|0|hwmon|swmeter|-|32bit

Tue Nov 17 12:23:43 2020: configuring for 44100Hz, period = 256 frames (5.8 ms), buffer = 2 periods

Tue Nov 17 12:23:43 2020: ALSA: final selected sample format for capture: 24bit little-endian in 3bytes format

Tue Nov 17 12:23:43 2020: ALSA: use 2 periods for capture

Tue Nov 17 12:23:43 2020: ALSA: final selected sample format for playback: 24bit little-endian in 3bytes format

Tue Nov 17 12:23:43 2020: ALSA: use 2 periods for playback

--- snip--

The attachment shows you there are 4 capture-channels.

The bug is described here by another person too:
https://linuxmusicians.com/viewtopic.php?f=64&t=21380

My opinion is that somewhere in development of kernel alsa has lost it's
capability to configure more than 2 capture-channels.
I wonder why nobody else is complaining, maybe because it's an usb-device ?

If you need more information, please tell me which,
i will provide them.

best regards Harry
---
ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.20
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC0', '/dev/snd/hwC0D2', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D9p', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D2c', '/dev/snd/pcmC0D1p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CurrentDesktop: XFCE
DistroRelease: Ubuntu 18.04
HibernationDevice:
 RESUME=none
 #RESUME=UUID=dfde7c59-5c49-4cce-9ba4-b8ac106ae5cb
InstallationDate: Installed on 2017-05-20 (1277 days ago)
InstallationMedia: Xubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215)
IwConfig:
 lo no wireless extensions.

 enp0s31f6 no wireless extensions.
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 046d:c501 Logitech, Inc. Cordless Mouse Receiver
 Bus 001 Device 002: ID 05e3:0716 Genesys Logic, Inc. USB 2.0 Multislot Card Reader/Writer
 Bus 001 Device 004: ID 046a:010e Cherry GmbH
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: System manufacturer System Product Name
Package: linux-hwe-5.4
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-54-generic root=UUID=af5502e5-b124-4e34-a0d2-ece834ccdc87 ro rootflags=subvol=@ ipv6.disable=1 fastboot plymouth:debug ipv6.disable=1
ProcVersionSignature: Ubuntu 5.4.0-54.60~18.04.1-generic 5.4.65
RelatedPackageVersions:
 linux-restricted-modules-5.4.0-54-generic N/A
 linux-backports-modules-5.4.0-54-generic N/A
 linux-firmware 1.173.19
RfKill:

Tags: bionic
Uname: Linux 5.4.0-54-generic x86_64
UpgradeStatus: Upgraded to bionic on 2018-11-23 (726 days ago)
UserGroups: adm audio cdrom davfs2 fax lpadmin netdev netzuser plugdev sambashare scanner sudo vboxusers video wireshark
_MarkForUpload: True
dmi.bios.date: 05/16/2018
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 3805
dmi.board.asset.tag: Default string
dmi.board.name: H170-PRO/USB 3.1
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr3805:bd05/16/2018:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnH170-PRO/USB3.1:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: SKU
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer