[pulseaudio-discuss] [Fwd: Re: [Jack-Devel] pa vs jack2]

[Ng Oon-Ee]

Please find below some details from Jack2 dev nedko on the
dbus-specifics, with relation to a recent topic on starting
module-jack-sink/source on surrendering control of the sound card to
Jack.

        Patrick Shirkey <pshirkey at boosthardware.com> writes:
        
        > Hi,
        >
        > I just spotted this on the pa list.
        >
        >
        https://tango.0pointer.de/pipermail/pulseaudio-discuss/2009-October/005302.html
        >
        > ==================
        >
        >>  I'm sure the Jack folk know better than I on the D-Bus name,
        but
        >>  jack_control status seems to work fine to tell me when Jack
        is ready for
        >>  use, and it communicates via dbus as well...
        >
        > Last time I checked they had a name they were picking before
        > actually spawning off the jack audio daemon. As long as things
        are
        > that way round this is not useful for PA's needs.
        >
        > ==================
        >
        >
        > Can anyone confirm or deny? Seems to be a bit of a blocker to
        proper
        > dbus integration if PA cannot work with the existing jack2
        method for
        > registering a name with dbus.
        
        "jack_control status" does not check whether dbus name is owned.
        It
        checks whether JACK server is started. There are also a D-Bus
        signals
        that are emited when JACK server starts/stops. D-Bus name is
        reserved
        when controller is activated and that has nothing to do with
        whether
        JACK server is started. The controller object is the one who
        starts JACK
        server. It is a persistent endpoint to control and monitor JACK
        server.
        
        So, if pulseaudio needs polling, it can use the
        org.jackaudio.JackControl.IsStarted() method.
        
        If it needs notification mechanism, it should subscribe for the
        org.jackaudio.JackControl.ServerStarted and
        org.jackaudio.JackControl.ServerStopped signals.