After upgrading 12.04 to a new kernel
Jack fails to aquire my Mobile Pre USB Soundcard with the following messages. When starting with Qjackctl or Cadence:
ERROR: cannot register object path "/org/freedesktop/ReserveDevice1/Audio2": A handler is already registered for /org/freedesktop/ReserveDevice1/Audio2
And when starting in the terminal:
creating alsa driver ... hw:2|hw:2|128|3|48000|0|0|nomon|swmeter|-|32bit Using ALSA driver USB-Audio running on card 2 - M Audio MobilePre at usb-0000:00:14.0-2, full speed configuring for 48000Hz, period = 128 frames (2.7 ms), buffer = 3 periods ALSA: final selected sample format for capture: 16bit little-endian ALSA: use 3 periods for capture ALSA: cannot set hardware parameters for capture ALSA: cannot configure capture channel Cannot initialize driver JackServer::Open failed with -1 Failed to open server
Pulse Audio is not running either:
E: [pulseaudio] module.c: Failed to load module "module-jack-source" (argument: ""): initialization failed.
All this worked perfectly well on the very same Laptop (Lenovo Ideapad) with 12.04 and it still works, if I just use the kernel, that came with KXStudio for 12.04.
I have 2 questions:
1.)What does this mean:" A handler is already registered" ? Who has registered that handler? Could I do anything about that?
2.)Is there a way to keep the USB-Soundcard from being (mis)configured by any automatisms such as dbus, pulseaudio etc? It may only be configured by Alsa and thus be available excluselively for Jack.
In the end I risked a total upgrade to 12.10 and now I experience a strange and amazing result: everything works so perfectly well that I suspected qjackctl is failing to detect any xruns. It is not: there simply are none.
Not only is the MAudio configured and switched on automagically, it also performs much much better than ever before. Even with the Pulse-jack bridge active I need to do really heavy stuff in Ardour3 to provoke an xrun at all.
While this is all nice and cool and swag and stuff I still would be happy to learn, what could have been the problem in 12.04. Anyway, I flag this issue solved OK?