[LAD] [Jack-Devel] jackd/jackdbus : D-Bus or not D-Bus...

Krzysztof Foltman wdev at foltman.com
Tue May 19 13:24:03 UTC 2009

Paul Davis wrote:

> there are other applications that want to start (and potentially) stop
> jack. if a d-bus aware version of jack is installed instead of the
> non-dbus-aware one, then applications that do not use the control API
> for this will fail. ergo: installing the dbus aware version
> (potentially) breaks the operation of control apps that predate the
> control API. not the end of the world, but not good either.

The current state is that it starts the "unintended" version of jackd,
and confuses almost everyone in the process. Or fails to start the
server at all, because DBUS version is already running in background,
confusing everyone else.

In my opinion, plain refusal to start with incompatible version is less
dangerous, because it gives the end users a necessary information (about
different pieces of software being incompatible). The users may then
decide if they prefer the "proven-but-possibly-dead-end" tool set
(qjackctl and friends) or "still-experimental-but-promising" tool set
(laditools etc).

The current model is misleading. In some cases it doesn't tell when the
system works differently to what user intended. In other cases, it
doesn't explain the primary cause for the server failing to start. My
reaction to this kind of software is to uninstall it as quickly as possible.

> also, the current jack ecosystem is already deeply confused by the
> existence of jack1 and jack2, which have a few very subtle but
> important differences. adding yet another
> almost-the-same-but-different option is a PR disaster waiting to
> happen.

Well, the damage is already done, see Fons' email and probably dozens of
people who had the same experience but never bothered to report it. I
think people who spent some time with Linux audio have plenty of
experience with incompatible parallel APIs - OSS vs ALSA, ALSA vs JACK,
JACK MIDI vs ALSA sequencer, raw MIDI vs sequencer MIDI. That's Linux
Audio SNAFU. At least when you have JACK MIDI vs ALSA seq MIDI problem,
nothing is pretending to work, the apps just don't see each other's MIDI
ports (+/- a2jmidid, but that's for advanced users).

On the other hand, this "two conflicting JACK executables that appear to
be compatible but aren't, and they may be picked randomly in some
instances" is a whole new thing, and nobody is used to it yet ;)


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