Re: [gentoo-user] USB Audio ?

[Mick]

On Tuesday, 14 May 2019 04:24:46 BST Jack wrote:
> On 2019.05.13 23:10, tuxic@××××××.de wrote:
> > Hi,
> >
> > is it somehow possible to play USB-Audio on a PC without one of these
> > USB-dongle-"soundcards" (DACs)?
> >
> > I searched the web and only got links to those dongles...
> >
> > On the other hand: On the forum of the developers board one post
> > spokes of a "dummy" USB-Audio device...
> >
> > How can I acchieve this?
> >
> > Thanks for any help in advance!
> > Cheers!
> > Meino
>
> It's not clear what you really want.  Why would you want USB audio
> without an actual USB audio device?  Without a USB audio
> dongle/device/whatever, what would you have to actually produce
> sound?    I can imagine a "dummy" USB audio device - but I can imagine
> it for testing the software, but not actually producing any sound, so
> why would you want it?
>
> Jack

As Jack said, a USB connector passes digital signals from your audio source 
(PC media player) to a USB connected device, which is able to convert the 
digital signals to analogue audio (DAC chip).  Without such a converter you 
wouldn't be able to hear sound coming out of whatever you connected to the USB 
port.

If you connect USB speakers, a soundbar, USB-C earphones and the like, they 
all have some DAC converter chip on them to turn the binary USB input into 
audible sound.  There's Class 1 and Class 2 USB audio devices.  Class 1 can 
process up to a maximum of 24-bit/96kHz files, while Class 2 can reach up to 
24-bit/192kHz - if you have this quality of audio files.

A dummy audio driver pretends it is an audio device for testing the audio on 
your PC, but it will not produce audio output.

I found this page explaining how USB audio works:

https://www.edn.com/design/consumer/4376143/Fundamentals-of-USB-Audio

-- 
Regards,
Mick