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).
Regards,
Sergei.
Mon, 8 Sep 2014 16:32:27 -0700 от "Paul A. Steckler" <steck@xxxxxxxxxxxxx>:
Well, I meant, keep PulseAudio running, but still use ALSA without
using the PulseAudio server device, which
other applications may want to use.
-- Paul
On Mon, Sep 8, 2014 at 4:11 PM, Sergei Steshenko
<steshenko_sergei@xxxxxxx> wrote:
>
>
>
> Fri, 5 Sep 2014 09:38:54 -0700 от "Paul A. Steckler" <steck@xxxxxxxxxxxxx>:
>
> I have an app that uses the ALSA library on Linux.
>
> The app calls snd_pcm_open() to open the capture device. Currently,
> I use "default" as the name of the device. According to "arecord -L", the
> default device is the PulseAudio server.
>
> Is there a way to bypass PulseAudio, and communicate with the
> hardware directly?
>
> I've tried using "sysdefault" and "hw:0,0" as the name of the device,
> and in both cases, I get an error that the device is busy. Is that because
> PulseAudio has monopolized the device?
>
> -- Paul
>
>
> "Is there a way to bypass PulseAudio" - one can (simply) stop PulseAudio
> server, e.g.: http://jan.newmarch.name/LinuxSound/Sampled/PulseAudio/ ->
> http://www.linuxplanet.com/linuxplanet/tutorials/7130/2 .
>
> Regards,
> Sergei.
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