Sergei, Paul, list...
On Sep 9, 2014 11:01 AM, "Sergei Steshenko" <steshenko_ser...@list.ru>
wrote:
>
> What you want is impossible in principle, regardless of PulseAudio
specifically (i.e my statement applies to any kind of sound server with
similar functionality) and ALSA speicifically (i.e my statement applies to
any kind of direct HW access interface).
>
> The point is that for an HW device to function a stream of audio samples
must be sent into it, and the device must be configured WRT sample rate. If
a program takes control of a sound device, no other program can use it -
how do you imagine one program sending 44100Hz samples and at the same time
another program sending 96000Hz samples to the same device ?
>
> So PulseAudio is among other things a sophisticated mixer doing sample
rate conversion when necessary and adding streams with coefficients (i.e.
k1 * s1 + k2 * s2 + ... + kN * sN) from different sources, the
coefficients representing volumes, and sending the resulting stream into
the HW device.
>
> I yet to have find out whether PulseAudio can be running using one sound
card, and ALSA directly for another sound card (this is my setup - I have
two physical sound cards).
Sergei, the setup you describe is exactly the one I use all the time on my
laptop and on my desktop.
Laptop :
Internal sound card (Intel panther point) is the default Alsa device used
by Pulse for mic, speakers and headphone output.
External sound card (Audioquest Dragonfly USB) is the Alsa device used
directly by Guayadeque for playing music. Here I must use plughw since the
Dragonfly wants everything at 24 bits.
Desktop:
Internal sound card (Intel on-board) is the default Alsa device used by
Pulse for speakers and headphone out.
There is some kind of sound capability on the Nvidia graphics card I
recently installed, but it is currently unused.
Internal sound card (ASUS Xonar DX) analog out is the Alsa device used
directly by Guayadeque for playing music. I use the analogue output of the
DX through an old spare power amplifier to drive some decent speakers.
This way, system noises and other audio junk is handled gracefully by Pulse
and my music listening is not disturbed by Pulse resampling everything for
me.
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