[arch-general] Basic questions about Linux's sound system

[Peter Nabbefeld]

Am 31.01.2017 um 11:43 schrieb Ralf Mardorf:
> Hi,
>
> I only replied because your graphic shows "Rosegarden". If you should
> use Rosegarden, you should get rid of pulseaudio.
>
> [rocketmouse at archlinux ~]$ pacman -Qi rosegarden | grep Dep
> Depends On      : liblrdf  dssi  fftw  lirc  perl  qt5-tools  shared-mime-info  liblo>=0.28
> Optional Deps   : lilypond: notation display
>
> Pulseaudio is not good for this kind of task.
>
> ALSA is the only thing required for sound, since it's the layer with
> the audio drivers. Pulseaudio needs ALSA, but ALSA doesn't need
> pulseaudio. The people responsible for pulseaudio made a lot of noise
> when pulseaudio didn't work correctly with ALSA, while ALSA on it's own
> worked. It's a "consortium" of coders who cause a lot of trouble, not
> only with pulseaudio. Soundservers such as pulseaudio or jackd provide
> some comfort. For the desktop I just use the bell (beep of the PC
> speaker) and an audio interface for webradio, videos and things like
> this. Only for audio productions I'm using a sound server, jackd. You
> only need crappy sound servers such as pulseaudio for software that is
> bad programmed, AFAIK it's skype or if you want to listen to webradio
> and recycle bin crackles at the same time, without using ALSA's dmix.
> AFAIK pulseaudio allows you to play a video and a media player at the
> same time using different sample rates. In short, without some kind of
> "patch bay" only one app could use a single audio device. A sound
> server provides the comfort to connect several apps to a single audio
> device. From my audio engineer's point of view, everybody who uses
> pulseaudio either makes something fundamentally wrong or is a lazy
> android who wants to listen to several sound sources at the same time,
> without configuring plain ALSA to do it. I doubt that many humans
> seriously like to listen to several sound sources at the same time. For
> audio productions OTOH it makes sense to have a virtual patch bay that
> is real-time capable and in addition easily allows to chose sample rate
> and frames, so jackd makes sense for such a task, but even in
> this context using pulseaudio still would be counter-productive.
>
> IMO pulseaudio is good for absolutely nothing, but just could be the
> cause for serious issues.
>
> I installed a dummy package, just in case pulseaudio should be a
> hard dependency for software, that actually doesn't need it, because I
> don't want to rebuild those packages without the pulseaudio requirement.
>
> [rocketmouse at archlinux ~]$ pactree -r pulseaudio
> pulseaudio
> └─pulseaudio-alsa
>   ├─cinnamon-settings-daemon
>   │ ├─cinnamon
>   │ └─cinnamon-control-center
>   │   └─cinnamon
>   └─vokoscreen
> [rocketmouse at archlinux ~]$ pacman -Qi pulseaudio | head -12
> Name            : pulseaudio
> Version         : 2013.08.18-1
> Description     : Dummy package
> Architecture    : any
> URL             : None
> Licenses        : None
> Groups          : None
> Provides        : pulseaudio
> Depends On      : None
> Optional Deps   : None
> Required By     : pulseaudio-alsa
> Optional For    : fluidsynth  phonon-qt4  phonon-qt5  speech-dispatcher
>
> It's to funny, I never used cinnamon and never used vokoscreen,so I
> could remove them. However, in the past I used some software with a hard
> dependency to pulseaudio without having pulseaudio installed. Much
> likely cinnamon and vokoscreen will work without pulseaudio, too. The
> old AUR once provided gnome-settings-daemon-nopulse.
>
> [rocketmouse at archlinux ~]$ ls /var/aur3/gnome-settings-daemon-nopulse/
> gnome-settings-daemon.install  PKGBUILD
>
> Regards,
> Ralf
>

Thank You Ralf,

now as I understand Pulseaudio ist also a sound server, I've changed my 
overview to this - hopefully this time it's correct:


                     +-----------+
                     |   Totem   |
    +------------+   +-----------+   +-----------------+
    | Rosegarden |   | GStreamer |   | Appl. using PA  |
    +------------+---+-----------+---+-----------------+
    |   Jack     |            Pulseaudio (PA)          |
    +------------+-------------------------------------+
    |        ALSA           -          Bluez           |
    +--------------------------------------------------+

As I need Jack for Rosegarden (though I'd not really need Rosegarden, 
just playing a little bit around for interest in it as an application), 
I'd next look which programs use PA to find out, if it is needed by any 
important piece of software, so I could probably remove it.

However, I'll need bluez-alsa then to get my headset working, because 
bluez > 5 doesn't support that anymore (probably even dependent on PA).

Kind regards
Peter