[CentOS] sound problems... config?

[ken]

On 03/28/2017 11:40 PM, Alice Wonder wrote:
> On 03/28/2017 05:53 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
>
> I have similar issue with USB headphones. Worked fine in 7.2 but in 
> 7.3 I frequently have to unplug and plug them back in before it 
> finally is able to be selected from the menus as my output.
>
> Once it is selected, it stays selected until next reboot. 

Alice,

Thanks for your reply.  I believe you and I are looking at two separate 
problems.  My system is capable of switching between the onboard 
speakers and the headphones with no problem at all (when the sound is 
working at all).  That is, when there's sound out of the onboards, I can 
plug in the headphones and sound instantly comes out of them, and vice 
versa... even in the middle of one and the same video.

In your case the problem may have more to do with USB.  USB is 
notoriously slow... at least it used to be.  This is due to timing, 
i.e., after loading the USB sub-system, the system has to query the USB 
device to find out what it is (e.g., mouse, joystick, headphones, 
touchpad, etc.) and there are a bazillion different kinds of USB 
devices... a long list of things to query.  Not only that, but a single 
query takes time: the system has to give the device time to respond-- it 
used to be a second or two.   And there are ever more USB devices.  
Maybe too your headphones are near the bottom of the long list of USB 
devices.

I don't know that this is your situation.  It could be something else (a 
half dozen other hang-ups).  But you might want to test by plugging in 
your USB headphones and then leaving the plug in, waiting a couple 
minutes to see if they start to work.

Alice, could you please post the output of these three commands (for 
comparison purposes):

uname -r
ps -ef|grep -i alsa
aplayer -L

Thanks.