[LAD] two reasons for jack2 .. and the problems with it.

[Stéphane Letz]

Le 7 juin 2010 à 01:49, Robin Gareus a écrit :

> Well I did the switch: jackd here is now jackdmp.. and [almost]
> everything works just like before.
> 
> The motivation for this was to benefit from the re-loadable backend
> feature of jackdmp for two reasons:
> 
> - to be able to quickly switch between internal and external soundcards
> - have JACK sessions survive suspend/resume cycles (using dummy backend)
> 
> After some initial testing I was quite enthusiastic. It looks very
> smooth on the surface. but - or course - the devil is in the details:
> 
> Calling `jack_control sm` drops existing connections to system:* ports.
> OK. They may be different but here they're not. no problem: this can be
> remedied with a simple shell script.
> But worse: both patchage (v0.4.4) & qjackctl (v0.3.6.22) go haywire
> (either 100% CPU usage,  disconnect or crash) when replacing the
> back-end while they're running. I have not yet found a pattern in the
> app's behaviour.

Any log to help finding if jack2 is the problem?
> 
> Qjackctl's issue can be worked around by stopping it before doing the
> switch: 'dbus-send --system /org/rncbc/qjackctl org.rncbc.qjackctl.stop'
> but re-starting it after the switch fails if the qjackctl setup does not
> match the current active hardware (it tries to start a 2nd jackd
> instead); otherwise it works just fine.
> 
> ardour2 disconnects if I switch directly between two alsa backends.
> however going alsa,hw:0 -> dummy -> alsa,hw:1 works.
> 
> Clearly there's some issue remaining to be worked out.
> 
> The good news: both mplayer and alsa-plug have no problem with me
> changing the jackd-backend (while retaining sample-rate and buffersize)
> even while they're playing; so I'm good most of the time :)
> 
> The scripts I use are available at http://rg42.org/wiki/jack2contol
> 
> Has anyone else ventured down that road and has a similar setup running?
> Can someone reproduce these problems?
> 
> Cheers!
> robin


Stéphane