REW on Linux with USB ADAC not operational

[tombarclay]

System : LinuxMint20.2
ADAC : Yellowtec PUC2

Problem, Plug in USB ADAC and its seen by system as usb device (in terminal > lsusb to print out usb address etc) but REW does not see the device in the preferences soundcard tab.
What do I need to do the connect the device to the application ? Any help appreciated.

 

[John Mulcahy]

I am no Linux expert so can't help, but Pavel posted this in another forum which may be relevant: REW is programmed in java which supports only alsa in linux (no PA nor jackd), and enumerates cards only (i.e. devices listed by aplay -l). The alsa javasound layer does not list PCM devices (listed by aplay -L), e.g. those defined in .asoundrc.

 

[jschwender]

please check the output of the following commands: arecord -l and aplay -l
Check the alsa modules loaded by cat /proc/asound/modules
(run this as logged in user in a terminal window or on a console).

 

[tombarclay]

Thanks for all your replies. Having beat my head against the issue for a couple of days my conclusion is that its not (yet) suitable for a Linux deployment. John Mulchay's reply somewhat confirms this. I have decided to us it under Windows for the time being.
As an aside I have played around with Ubuntu Studio ,(as it claims to be fully configured for Audio work), to try and understand the issues of using my YellowTech USB card within that framework. Eventually I hope to understand the config issues with ALSA, JACK and PULSAUDIO layers etc to revisit the REW question. It seems to me that adding a Java JACK layer would be a way to go ... but I guess that is for the future. Thanks again. ... Tom

 

[jschwender]

Jack is only a audio routing application – for i/o it relies on ALSA. ALSA is kernel-integrated. Pulseaudio is same as Jack only a sound routing application. So at the end neither a JACK-Java nor a PulseAudio-Java makes sense for measuring purposes, because it is a fundamental requirement that you have a direct access to input and output audio data stream without any re-coding. Most of the a USB sound interfaces out there are compatible with USB-AUDIO protocol, and works under Linux+ALSA using a class driver, and without any further configuration or driver installation.

 

[jschwender]

I spoke to the manufacturer, they say, the device is UAC2 compliant, but the linux detection fails ( he did not say why…) and recommended a special firmware which makes it work under linux:
https://www.yellowtec.de/puc2/downloads.html
I don't have the hardware, therefore i cannot try and test. Maybe you do.

 

[tombarclay]

Thanks for your help. I will try the PUC to firmware change over the weekend and get back to you. Having absorbed your explanation of the Linux sound API layering, though not yet fully understanding, I dumped the ALSA devices and PCMs using aplay and arecord commands (see attached) and it appears that FULL PUC2 2 channel play and record interface is not exposed. This fits with what you say. Lets see what the firmware change brings !!!

 

[amarillo]

I have a similar problem. I'm trying to get a TASCAM US-122L running under linux (ubuntu 18.04, kernel version 5.4.0).
I more or less followed alsa-project.org/wiki/Matrix:Module-usb-us122l and managed to get the card working with jackd (it shows also in
cat /proc/asound/cards ).

However, it is not listed either in aplay -l nor in arecord -l. From what I read above, I won't be able to use jack within REW ?

I'm not very familiar with Linux sound layers yet (ALSA, PulseAudio, jack), but since I saw that it is possible to create virtual ALSA devices and/or alsa-to-jack bridges I'm wondering if this would be an option. But before I spend hours trying that, I thought I'd ask before if anyone has experience with that or already knows that this won't work...

Any advice welcome!

 

[jschwender]

That sounds to me like a locking issue. Alsa devices can only be accessed exclusively: if one application grabs it, other applications cannot connect to it. That is one of the main reasons why higher layer routing systems like PulseAudio or Jack exist, they can deal with multiple in and out streams simultanously. Despite this, this locking is not a bug, it is a feature: because shared access always means some kind of signal processing, and this is sometimes something you definetly don't want, especially for measurements. Solving this problem is to find out what application locks the device and shut down this application. I have no explicit experience with Jack, but i bet there is a service running that grabs the alsa devices – with PulseAudio, this is definetly the case. If i start a pulse mixer for example, rew does not find alsa devices any more. If i stop this application, it takes like 4 seconds until rew finds them (after restarting rew). Same with other alsa applications. Audacity is another example that grabs the alsa device, locks it and if i start rew it does not find them.

 

[amarillo]

Thanks. I don't think it is a locking issue though. I've seen what you describe in the past, but then aplay -l would show something like this:

card 0: PCH [HDA Intel PCH], device 0: ALC3235 Analog [ALC3235 Analog]
Subdevices: 0/1

(where 0/1 indicates, that it is not available but locked)

However, I've disabled PulseAudio and also jack, but no luck with getting the usb_stream device working. It simply doesn't show in aplay -l, and only seems to work when the .asound.rc is present that registers the 'usb_stream' device somehow. I've noticed that it won't show up in other programs either (e.g. even the jack GUI frontend), but I can manually use 'usb_stream:1' as an ALSA device name and it works.
In REW, there is no option to manually enter a device name, I guess it simply lists in the dropdown menu what aplay -l shows ?

 

[jschwender]

When i quickly look over the code of the module, it seems that this is still a "first proof of concept " implementation and intended to provide jack-pcm functionality, It looks like it is not working with snd_usb_audio, and therefore alsa provides no device except for the jack interface.

 

[tombarclay]

HI again, it seems that my PUC2 is currently not compliant with UAC2. Its a hardware issue and the manufacturer has quoted me for an upgrade (approx £250 UKPounds) to make it accept the required 2.5 firmware upgrade. Needless to say as a retired electronics design engineer I am not prepared to make that investment and have dedicated an old Windows laptop as my REW platform. I am thankful to all as I now have a better understanding of the roles that US , ALSA, JACK and PulseAdio play.