PulseAudio and sound apps (was: Re: Orphaning a few packages)

[Fernando Lopez-Lezcano]

On Thu, 2009-04-23 at 23:01 +0200, Lennart Poettering wrote:
> On Thu, 23.04.09 15:36, Callum Lerwick (seg at haxxed.com) wrote:
> 
> > > That solution (Jack on top of PA) does not work not because of mmap
> > > access requirements of Jack. It does not work because Jack and PA are
> > > _conceptually_ different and cater to different segments of the audio
> > > users of Fedora and other distros. 
> > > 
> > > Jack is designed for very very low latency. Jack needs access to the
> > > hardware devices. It cannot and should not run on "top of something
> > > else". The requirement is not capricious. It is designed that way, and
> > > works very well. Please don't break it. 
> > 
> > +1
> > 
> > The thing to do route Pulseaudio through Jack. Pulseaudio already has a
> > Jack plugin.
> 
> As I already pointed out there is no point in running PA and JACK on
> top of each other. Certainly not JACK on top of PA and not the other
> way either.
> 
> PA and JACK have different purposes. For pro audio PA needs to go out
> of the way and that's what it does with the device reservation
> logic. 
> 
> The Jack plugin for PA is more a toy for exotic uses. It is nothing to
> enable by default. Running PA on JACK is simply pointless, there is
> simply no reason why you'd want that. 

Sorry, no, no reason that you can see. 

> You don't want to have event
> sounds mixed in your pro audio stream, you don't want ekiga audio in
> it, and you don't want flash sounds or rhythmbox or totem streams
> it. 

In the general case that is probably true. 

> The whole discussion of something like this is just complete and
> utter nonsense.

Nope. The dividing line between the two worlds is actually made of
shades of grey, we don't live in a black and white world. Just because
you don't do it or can't think of an application does not mean it is
"utter nonsense"[*]. 

> So, no, "the thing" is NOT "to route PA through Jack". The thing is to
> not have them interfere with each other and cooperate. And that's what
> has been implemented now.

Sure, on that we agree completely. 
-- Fernando


[*] for example: an art installation that takes several audio feeds
coming from web browsers and processes them through a "professional"
audio chain running under Jack, records the multichannel output to
Ardour and then perhaps ships the whole thing to another place maybe
halfway around the world using netjack or jacktrip. Yes, people do that
kind of thing :-)

Well, of course, thinking about it, you can also say this is "utter
nonsense"... oh well...