Re: [gentoo-user] USB sound

[Mark Knecht]

On Tue, Apr 28, 2020 at 6:51 AM Peter Humphrey <peter@××××××××××××.uk>
wrote:
>
> On Tuesday, 28 April 2020 14:18:52 BST Mark Knecht wrote:
>
> Has KMail started misbehaving again? I'm certain I read a reply from
Michael,
> but now there's no trace of it after a reboot (see below). Anyway, I
created
> an /etc/asound.conf with the content he recommended. That gave me sound
back.
> Thanks Michael.
>

I don't use asound.conf on any of my machines. Be careful about mixing
instructions from multiple folks trying to help you. It will confuse us (or
me anyway) to no end.

> > 1) First, if you really don't want the intel stuff loaded then either
don't
> > build it in your kernel or (easier - it's what I do) just blacklist the
> > intel sound driver. The following link has some instructions which
explain
> > the process.
>
> > https://www.techtimejourney.net/how-to-blacklist-a-sound-card-in-linux/
>
> Thanks for the pointer, Mark.
>
> > Please provide the output of
> >
> > ls /proc/asound
> > cat /proc/asound/cards
> > cat /proc/asound/modules
>
> # ls /proc/asound
> card0  card2  Device   HDMI   modules  pcm  timers  version
> card1  cards  devices  hwdep  oss      seq  USB
>
> # cat /proc/asound/cards
>  0 [HDMI           ]: HDA-Intel - HDA ATI HDMI
>                       HDA ATI HDMI at 0xfbe60000 irq 59
>  1 [USB            ]: USB-Audio - HD Webcam USB
>                       HD Webcam USB HD Webcam USB at usb-0000:00:14.0-6,
high
> speed
>  2 [Device         ]: USB-Audio - USB Audio Device
>                       C-Media Electronics Inc. USB Audio Device at
> usb-0000:00:14.0-13, full speed
>
> # cat /proc/asound/modules
>  0 snd_hda_intel
>  1 snd_usb_audio
>  2 snd_usb_audio
>

OK, so card 0 is using snd_hda_intel. Card 0 is most likely the default
location that sound is going. Blacklisting it will help. That said you have
2 USB devices so we need to be careful about extra confusion there. For
simplicity you might just unplug the webcam (if you can - if this is a
built-in in a laptop then I understand you have limitations.)

> > 1) First, if you really don't want the intel stuff loaded then either
don't
> > build it in your kernel or (easier - it's what I do) just blacklist the
> > intel sound driver. The following link has some instructions which
explain
> > the process.
> >
> > https://www.techtimejourney.net/how-to-blacklist-a-sound-card-in-linux/
> >
> > Restart Alsa and double check the cards and modules shown in
/proc/asound.
> >
> > 2) As you are on KDE you likely have pulseaudio running. Run
pavucontrol,
> > run Firefox with some audio and see where you are sending Firefox audio.
>
> Nope. No pulseaudio.
>

What is the output of pulseaudio at the command line?

Or maybe just no pluseaudio tools, or whatever it's called on Gentoo
assuming it's a separate package. I'm no longer running Gentoo (I just find
this list the best place to get real info) A quick google for pavucontrol
suggests you can emerge media-sound/pavucontrol to get it.

Use KDE systemsettings, search for sound, choose 'Multimedia', Under 'Audio
Volume' what do you see? What device is set as default? (This part of
systemsettings is very similar to pavucontrol but it doesn't give you the
VU meters which are nicely visible to see what apps are generating audio.


> > 3) You probably don't have to mess with Alsa configuration itself to fix
> > this so keep it simple for now. We can go there later if need be.
>
> Meanwhile there are a few complications. First, I also have a webcam with
a
> microphone. I should have unplugged this before asking my question.
>

Agreed. Leave it disconnected for now for simplicity.

> Second, there's a sound driver in my Radeon Pro WX 5100, which I may want
to
> experiment with later if I can find a way to extract the sound from my
> DisplayPort link (not HDMI after all; I was mistaken about that in an
earlier
> thread). I can't disable it anyway, as far as I know. It may account for
the
> Intel modules.
>

No problem. Either blacklist the driver (easy) or rebuild the kernel
WITHOUT the driver (easy). Either should get rid of snd_hda_intel

> Third, I haven't any alsa packages installed, except for alsamixer which I
> installed to help with this problem (it didn't). There's no starting or
> stopping alsa; KDE seems to have what it needs without alsa specifically.
> That's why I had no asound.conf; it's also why I rebooted instead of doing
> something less heavy handed. Then again, why do I need an asound.conf?
>

No. The fact that you can cat "/proc/asound" asound being "Alsa Sound" says
Alsa is running. Alsa talks to your sound card hardware and provides a
"single application" interface to the sound cards. Pulseaudio provides a
mixer so that multiple apps can all send sound to your hardware.

I personally don't think you need asound.conf until you prove that you have
a need to do some sort of non-standard configuration. That _might_ be
defining a different default card but KDE can do that for you in system
settings so my recommendation is no asound.conf for now. Use KDE as it's
intended and (over the long run) I think it's more maintainable. However,
you are completely free to use your system any way you want.



> --
> Regards,
> Peter.
>
>
>