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Problem with qjackctl when using multiple devices
Hello,
My audio/developer workstation has 4 audio/MIDI devices, they are:
M-Audio Audiophile 192 (vintage PCI, circa 2005 when they first came out)
EMU 0204 USB
AMD/ATI Southbridge onboard HD Audio with HDMI audio, etc..
Akai MPK Mini USB
...of course, I don't need all of those devices running at the same time, they're mostly there just for testing.
I'm having 2 issues with qjackctl:
1. qjackctl doesn't always list the interfaces in the same order, but it's recalling the selected interface based on index. For example, if I select hw:2 as my interface, that might be the EMU 0204 now, but when I reboot, hw:2 might be the AMD/ATI onboard audio, which may not even be able to start with the same settings as the 0204.
2. The Akai MPK Mini isn't an audio device, it's only for MIDI, but it's showing up as an interface (it may just be mis-reporting itself, I don't know)
#1 I think you could fix by having qjackctl remember the selected device by it's device ID or device name, instead of by the device index, as the kernel may not enumerate multiple devices in the same order at every reboot.
Re. Problem with qjackctl when using multiple devices
qjackctl just lists and identifies all system audio pcm devices exactly as the ALSA system software stack enumerates them.
it's a fact that sound devices are listed in the order their respective drivers are eventually loaded at boot time or detected whenever they're plugged in (this is the case of the removable USB devices).
unfortunately this order of events isn't always deterministic as you may already noticed.
the solution is to force fixed slot indexes for each kernel device module--you tell that on the /etc/modprobe.conf or /etc/modprobe.d entries while on kernel system configuration settings or whatever it gets called on your distro of choice (mine is openSUSE and it's all done under YaST Hardware Settings / Sound devices)
you may also go and read this topic on ALSA wiki. it gives you all the necessary insight ;)
whether the MPK gets listed as a PCM device is beyond me. however. i do have a MPK25 here and it's listed there too. i just mark it once with some higher slot index on the modprobe.conf settings and gone with it :)
cheers
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