[CentOS] USB audio on Centos-7

On Fri, Sep 29, 2017 at 09:02:08PM -0400, Fred Smith wrote:
> On Wed, Sep 27, 2017 at 12:08:59PM -0400, Fred Smith wrote:
> > On Wed, Sep 27, 2017 at 02:06:35PM +1000, Kahlil Hodgson wrote:

Below is an email from last year, and this is a followup or at
least related, so I'm including it below for your reference.

Using this USB "sound card" (it's not a card...) I can (as related
below) record input from a tape deckwith Audacity.

But what I haven't figured out how to do, though there must be some
incantation that works, is to simply play audio input coming in via
the USB device, through the speakers. Between Alsa and Pulse, I have
tried every option I can imagine that should make it work, but no go.

Anybody know what settings should be used for sending audio coming
into the system via a USB audio device, to the speakers?

thanks in advance!

Fred
> > > Most of the useful audacity stuff is in their wiki:
> > > 
> > > http://wiki.audacityteam.org/wiki/USB_mic_on_Linux
> > > 
> > > seems like a good place to start.
> > 
> > thanks, that probably is a good place to start. some of that
> > may be pretty old, but I'm checking it out. One could wish it
> > wasn't quite so terse, in spots.
> > 
> > Fred
> 
> OK, I spent several hours messing with it, including trying the
> things shown at the audacity URL above. But at that point, it was
> as if there was no input device there. gave up, went to bed.
> 
> next day I noticed that no audio played at all even without the 
> USB device, not from a DVD, nor a MP3 file, nor from any web
> video. so I figured some bit of hardware had gotten into some
> "I'm gonna play dead" state, so I did a full power off and reboot,
> after which I had normal audio again.
> 
> so I plugged in the USB device again and fed some audio into its
> line in. fired up Audacity and was able to select the USB device
> as its input, and it records!
> 
> the recording, when played back, is kinda jumpy, as if bits of
> it got lost on record, but otherwise doesn't sound too bad.
> Wondering if I need to try a realtime kernel... (or maybe I 
> should just pause the Folding At Home client while recording...
> there's a thing to try! :)
> 
> thanks for the hint!
> 
> Fred
> 
> -- 
> ---- Fred Smith -- fredex at fcshome.stoneham.ma.us -----------------------------
>   "And he will be called Wonderful Counselor, Mighty God, Everlasting Father,
>   Prince of Peace. Of the increase of his government there will be no end. He 
>  will reign on David's throne and over his kingdom, establishing and upholding
>       it with justice and righteousness from that time on and forever."
> ------------------------------- Isaiah 9:7 (niv) ------------------------------
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-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us -----------------------------
                         God made him who had no sin
                      to be sin for us, so that in him
                 we might become the righteousness of God."
--------------------------- Corinthians 5:21 ---------------------------------