[pulseaudio-discuss] Changing default soundcard on attach/detach of soundcards

[Mark Brown]

On Fri, Jul 16, 2010 at 11:41:33AM -0500, pl bossart wrote:
> > Well right now there are several projects (outside of my own) going on
> > in this field, but there does seem to be a little bit of disparity with
> > upstream people.

> > One project specifically is coming from the ALSA side and will get
> > support in PA. This project is very likely to become the defacto method
> > of operation on embedded systems and thus I would hope that people at
> > MeeGo would talk more openly about what they are doing so as not to
> > reinvent the wheel.

> If you are talking about the audio scenarios developed by Liam, I
> don't think there's any sort of conflict. it's my understanding that
> the scenarios are mainly to configure the hardware routing and
> performance of a given audio device using specific settings (eg voice
> volume, etc).
> This thread is more about what output will be used if you have
> multiple audio accessories or peripherals. It's one level higher I
> guess.

I missed the start of this discussion so I'm missing some context here
but there may actually quite a bit of overlap here - on systems like
smartphones it's very common for all the audio to be a single integrated
subsystem with multiple paths through it and the CPU as only one node in
that system.  Things like Bluetooth headsets wouldn't appear as a
separate sound card, they'd appear as an output option on the existing
sound card, and many audio paths will be connected directly through the
hardware without entering the PulseAudio domain.

Since there can be multiple paths through the system you can also end up
with different streams on the CPU being routed separately - the classic
example is having an MP3 playing to headphones and simultaneously
ringtone/alert sounds routed to both headphones and speaker.