Being the OP (I think) I didn't mean to stir controversy with my questions.
As
has been pointed out there are different ways to get to your preferred
configuration. Be that qjackctl, your own home brew, or some combination
of things.
Personally, most of the time, I just want it to
work so I can get about MY business and not the business of becoming a
guru on some part of the chain I need to get MY business done.
(My
OP came from a desire to figure out why a particular configuration
seemed to be so finicky. A particular laptop, the alsa interface, and
USB in/out ports presented by a Behringer X32, plugging the same usb
cable into another laptop, just worked every time. In order to
troubleshoot, I thought maybe I'd gain more insight by mimicking what
qjackctl does from the command line. But, when I tried to duplicate a
qjackctl start from the command line, was stymied as to how.)
The
entire linux audio (generic and pro) and the evolution thereof makes it
very difficult to get a clear picture of how it all works and how to
get what you want. (I've been a hardware/software engineer for 40 years,
messing with jack for the last 10 and still have questions...) To a new
comer or someone coming from a different audio platform, it would be
hard not to wonder if linux audiophiles aren't trying to make appear you
need to be some sort of linux mage to make it work. When in fact, you
just need to be a persistent investigator due to it's evolution (and
lack of cohesive end user documentation, again, because of it's
evolution). Oh, and some background in software, hardware, signal
processing, and system configuration doesn't hurt... For those who just
want to make music or record something quick...better stick to other
platforms and cough up the money that requires.
For
me the corner case argument is moot. There a myriad of use cases and
work flows. In my case, I, mostly, do theater work where playing
prerecorded tracks, controlling various devices (mixers, projectors,
sound fx, players, etc.), and following a script is typical. For sound,
that typically, means using player apps that may or may not be jack
aware (though, when the choice is mine, I just use LinuxShowPlayer,
since it knows JACK), so having the pulse ports just appear when jack is
started (by whatever means) is nice. And, while I RARELY use Skype,
being able to play youtube without having to mess around is handy. Yes, I
know I could get it all to play nice with just jack...but, that's not
what I prefer to use my time doing.
And, for full disclosure, I
use JACK to get to MIDI in ShowControl, the open source theater
production control software we are developing. But, I don't have any
desire to know more about the internals of jack than I need to to use it
as a tool. (but I need to figure out how to get that to start with the
preferred sound configuration...so I'll be looking in detail at things
like Christopher's jack-select, alas, deeper into the rabbit hole.) ;)
It's all good...just complicated. :)