[SOLVED]USB Microphone cannot be used by more than one application at the same time?

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mrVent
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[SOLVED]USB Microphone cannot be used by more than one application at the same time?

Post by mrVent »

Good day to you all!

A few months ago, I switched to Mint Cinnamon as my main system. Most of it is running perfectly smooth without any issues.
However, there is one major problem with my microphone. I'm using a Tonor Q9 Mono with a USB connection.

The device is PnP, and gets recognized correctly as an audio input device. I can select it as default input device in the pulseaudio GUI sound config utility. The level is also picked up correctly, and I can use it in Audacity without any problems.

However, for some reason, it originally did not want to work with ANY internet browser I tried. Vivaldi, chrome and firefox all gave the same result: I can select the Q9 as an input device, but there is absolutely ZERO sound picked up when making a recording on vocaroo or using GoToMeeting.

Interestingly, I managed to get it working with GoToMeeting by selecting a different input device (the internal microphone from the Thinkpad I'm using) system-side and selecting the Q9 only in Gotomeeting. Unfortunately, this has stopped working as of today. Vocaroo has still not picked up any sound input from the microphone in all this time, even with only one tab open.

All this has led me to believe that the microphone for some reason can only be used by one application at the same time, including the system itself. Why this is eludes me, and I would really appreciate any help.

Additional info: I have customized my /etc/pulse/daemon.conf to get the most quality out of my sound card, but have otherwise not touched any sound config files.
Last edited by mrVent on Fri Jan 15, 2021 9:09 am, edited 1 time in total.
Hoser Rob
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Re: USB Microphone cannot be used by more than one application at the same time

Post by Hoser Rob »

I suspect that's actually pretty normal behavior, see the 1st answer here: https://askubuntu.com/questions/963545/ ... ltaneously
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MrEen
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Re: USB Microphone cannot be used by more than one application at the same time

Post by MrEen »

If you're selecting the microphone manually in applications, you are usually forcing it to that application. Instead, leave the applications on default and make sure the mic is the default input on the Input Devices tab of pavucontrol by making sure the check mark for it is highlighted.
mrVent
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Re: USB Microphone cannot be used by more than one application at the same time

Post by mrVent »

@Hoser Rob:

That question pertains to using two input devices at the same time, whilst mine describes a problem that one input device can't be accessed outside of the local system. I appreciate you taking the time to link this, but I really hope that my problem does not stem from an intentional design choice of the OS.


@MrEen:

I've tried that previously, but did a quick re-check just to be sure. No improvement, unfortunately. When it is selected as fallback / default device, it still outputs no sound outside of Audacity and the configuration window.
Can you elaborate on "forcing it to that application"?
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MrEen
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Re: USB Microphone cannot be used by more than one application at the same time

Post by MrEen »

Your Audacity settings. Do they point to the device such as hw:2,0 (Some USB device here), or to default. If they point to the hardware, then only Audacity can access that hardware, until Audacity is closed.
mrVent
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Re: USB Microphone cannot be used by more than one application at the same time

Post by mrVent »

The Audacity settings are on "default", as before. It seems to use ALSA instead of pulse, though, from what I can gather.
Could the issue be pulseaudio-related?
Hoser Rob
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Re: USB Microphone cannot be used by more than one application at the same time

Post by Hoser Rob »

mrVent wrote:
Thu Jan 14, 2021 3:24 am
The Audacity settings are on "default", as before. It seems to use ALSA instead of pulse, though, from what I can gather.
Could the issue be pulseaudio-related?
pulseaudio is a layer on top of ALSA, which all Linux audio goes through. It's the base layer and yes, Linux audio can be a bit convoluted.

And trying to rephrase questions in such a way as to avoid hearing what you don't want to hear doesn;t help either. Whether intentional on the part of the OS or not (I think not), I think what I cited in my 1st post here is still correct.
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MrEen
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Re: USB Microphone cannot be used by more than one application at the same time

Post by MrEen »

mrVent wrote:
Thu Jan 14, 2021 3:24 am
Could the issue be pulseaudio-related?
It could. With pavucontrol showing the proper mic as fallback, change the Audacity settings to pulse instead of default and see if that helps.

Also check this command when there are issues:

Code: Select all

sudo fuser -v /dev/snd/*
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Re: USB Microphone cannot be used by more than one application at the same time

Post by mrVent »

Audacity unfortunately only gives me the option to use ALSA. It's a drop-down-menu, but the only entry is "ALSA". I remember reading somewhere that it doesn't provide pulseaudio compatibility. This might just be the reason it worked with the microphone at all.

Following my intuition that it's pulse-related, I went ahead and removed the pulseaudio package with the terminal - and lo and behold, Vocaroo was able to pick up the microphones audio stream. It was very loud and crackly, but it picked it up. I'd call that a massive step forward!

Audacity has been working fine the entire time since pulseaudios removal and it continued to record when the Q9 was selected directly and played the recording back without problem and distortion. Which makes sense considering that it relies on ALSA instead of pulse.

Of course, now the settings I made on the pulseaudio config are moot, since they're not used anymore. Does anyone know where the config files for sample rate etc lie for ALSA or am I barking up the wrong tree wanting to configure ALSA itself?
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Re: USB Microphone cannot be used by more than one application at the same time

Post by mrVent »

Good news!

I found the solution.

The problem was indeed pulseaudio-related; it was a single line in the configuration I wrote after a tutorial.
The offending line was "enable-remixing = no". This line pertains to allowing applications to remix the channels of an input device.
Since the Q9 is a mono input device, the browser needed it to be a stereo source in order to work with it, which my setting disallowed. Therefore the browser had access to the device, but could not send a valid input to the webpage.

After setting the enable-remixing option to yes, everything works as I wanted it to without having to give up on my higher quality pulseaudio config file. I found the solution on the "Troubleshooting pulseaudio" page under this link in an archwiki site: https://wiki.archlinux.org/index.php/Pu ... ixing_=_no

For anyone interested, I read that config of ALSA is possible, but you probably have to tinker with the modules and create the /etc/asound.conf yourself.

Thank you to everyone who helped and offered advice nonetheless. Without your ideas, I might have stumbled in the dark much longer. I'll mark this as solved now.
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MrEen
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Re: [SOLVED]USB Microphone cannot be used by more than one application at the same time?

Post by MrEen »

Nice work finding a solution mrVent! :D

And thanks for sharing the fix.

Regarding /etc/asound.conf (or ~/.asoundrc) I would generally say stay away from that. You're pretty much guaranteed of breaking PulseAudio using it. Many times people have had their sound troubles fixed by simply deleting the file they copied from somewhere on the net. Advanced users sometimes don't use PulseAudio and do need to create that file themselves, and have to learn what needs to be in the file specific to their hardware.
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