Re: sound problems... pulseaudio/pavucontrol

ken <gebser@xxxxxxxxxxxx> · Tue, 4 Apr 2017 19:28:27 -0400

On 04/03/2017 07:47 PM, Fred Smith wrote:
On Mon, Apr 03, 2017 at 12:53:54PM -0400, ken wrote:
On 04/02/2017 01:31 PM, Kay Schenk wrote:

On 03/29/2017 06:43 AM, ken wrote:
On 03/28/2017 08:53 PM, ken wrote:
The www has failed me with this, so I'm trying you guys.  Sound worked
great out of the box when I installed 7.2... Yay!  I could watch all
kinds of videos, like on facebook and youtube.  And I could listen to
most podcasts too.  But then something happened. It was either a
kernel upgrade or that I installed vlc (for watching videos on DVD)
and the whole stack of codecs for it... I don't know exactly when, but
at some point I no longer had sound with youtube  and other web
videos.  The videos played fine, just no sound.  Note that using vlc,
both video and the audio with it play just fine.  I need to select the
audio driver (from a list in a vlc menu), however, else the sound
won't work in vlc either.

If I go into the Applications menu, then System Tools -> Settings ->
Sound, under "Choose a device for sound output:" there are no devices
listed.  There used to be.

If I run "aplayer file.wav", nothing plays (no sound at all) and I get
the error "main:786: audio open error: No such file or directory".
If, on the other hand, I run "aplay file.wav -D plughw:0" (i.e.,
specify the/a device), I do get sound, the file does play.

I ran alsa-info.sh and it posted tons of info from it on my setup at
http://www.alsa-project.org/db/?f=1dba91886be054df4816000768a0f5b109947a48.

Yet it still doesn't tell me what's missing.

Anyone here have an idea...? or thoughts about where to look next?

tia,
ken
Still poking around my system for a solution, I found this comment at
the top of /usr/lib/systemd/system/alsa-state.service and two other
files in the same directory:

# Note that two different ALSA card state management schemes exist and
they
# can be switched using a file exist check -
/etc/alsa/state-daemon.conf .
The /etc/alsa/state-daemon.conf file consists of one line:

# Remove this file to disable the alsactl daemon mode
I understand that a daemon continually runs, waiting for an event and
then acts in some way in response, but it has to mean something more in
this context.  Anyone familiar with the internals of this?

I am not on systemd right now. I'm on CentOS 6.8. However, on an
openSUSE version I was. Sound problems were the bane of my
existence forever it seemed. So it maye take you a while to
troubleshoot this. Using JUST alsa you should be able to play
sound files at the command line. See:
http://www.alsa-project.org/main/index.php/Main_Page

I think I may have installed pulse-audio to get things working
under systemd with my GUI. What is your GUI? This may be a factor.

Thanks for the thought.  This is quite plausible.  I did a little
reading at the site you suggested and then at another which was
linked off of that.  I didn't find anything helpful at either place
yet... well, except that in the audio stack alsa is just one layer;
jack and pulseaudio ride on top of it.  Apparently sound on linux
can use all of them-- and others on both of the same layers-- all at
the same time.  This is probably what makes the configuration of
them all so challenging.

In the middle of reading those sites I decided to see if audacity (a
quite sophisticated and solid program) could somehow handle sound. I
installed it and fired it up.  Out of the box it didn't work.  But I
simply had to choose the correct device from audacity's drop-down
menu and, viola, it would produce sound from a loaded file.  Cool.

Right after that, I tried running "aplay
/usr/share/sounds/alsa/Front_Right.wav" and that worked.  Previously
it didn't, although (as noted above)  that same command when
specifying the device did (i.e., "aplay
/usr/share/sounds/alsa/Front_Right.wav -D plughw:0").  So apparently
installing and/or running audacity fixed something, but not
everything.

Another trippy discovery:  I used rpm to verify all the files
installed with all the alsa* packages and there were absolutely no
changes to any of them... they're all exactly as they were when
first installed.  Since sound worked exquisitely when I first
installed 7.2 on this box and no alsa files have been changed since
then, it's hard to find the fault with alsa.

Although aplay is back to working without having to specify the
device, I still don't get sound out of youtube videos (even though I
checked the settings and restarted Firefox), and gnome3's System
Settings -> Sound still lists no devices at all.  These are two
major failures.
Are you, perchance, using Firefox-52? At version 52, they switched
Firefox to use Pulse instead of Alsa. So you'll probably need to
fire up pavucontrol and mess with its sliders to get firefox audio
working.

Good call, Fred.  Just today I got a message when, doing testing, a 
message came up in Firefox that I needed to install pulseaudio.* Well, I 
never installed pulseaudio, but it's already installed,** so it must 
have been installed when I first installed 7.2 on this machine.  So then 
I tried, as you suggested, to start up pavucontrol and play around with 
it.  However, pavucontrol was not installed. So yumd'd it down and 
installed, then clicked on it in the Applications -> Sound & Video menu, 
but I just got a window pop with the message, "Fatal Error: Unable to 
connect to PulseAudio: OK".  Well, at least I finally have an explicit 
statement from the system that there's a problem.

*Okay, now we know you're a psychic.  Along with that Firefox message 
was a button for more info.  I clicked and it went to a webpage which 
basically said the same thing in more detail and with a link (allegedly) 
to more info, 
https://support.mozilla.org/t5/Videos-sound-pictures-and/Fix-common-audio-and-video-issues/ta-p/401. 

**As I did a day or two ago with alsa packages, I used rpm to verify all 
the pulse* packages (rpm -qaVv pulseaudio*) and found that none of the 
files in any of the packages had been altered at all.

I'm on Centos-7.3, and when I switched from 7.2 I found that some
things now are controlled by pavucontrol, and not by the volume
control in the top panel (I'm using Mate, not Gnome,... Gah, how can
anyone stand Gnome 3.x??) It's kind of a pain, I haven't yet found
a way to localize controls for all the various audio-producing tools
in one place. Does anyone know how to do that?

Sorry, I've never seen anything like that.

Does anyone know how to restart audio in systemd?  That might still
be worth looking into.
# systemctl list-unit-files --type=service
...
alsa-restore.service                          static
alsa-state.service                            static
alsa-store.service                            static
...

The above command showed the three alsa services, but nothing for the 
other audio software I've been poking around in: pulseaudio, jack, oss.  
Nor did I see anything else listed which told me it had anything 
directly to do with the system's audio.  Moreover, I don't have alsa 
running as a daemon.  So unless I'm misunderstanding what systemd does, 
I don't think it's playing a role in my sound problems.

Before doing audacity, I tried gnome's mplayer.  Geez, is that a
stinky pile of code.  Just selecting a directory where a file could
be selected ended up locking up the app; I had to do a kill to get
it off my screen.  Does that actually work for anyone?  If so, what
kind of files or net locations does it work for?

Thanks once more for your thoughtful suggestions.

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