Can't start Jack

I’m having trouble starting jack. It seems to be because ALSA: Cannot open PCM device alsa_pcm for playback. Nothing else is running audio afaik. I haven’t adjusted any audio settings to my knowledge. The only changes I had made to the system were to do with a tablet input and graphics.

I’m using Karmic, the 2.6.31-9-rt kernel and my 1010LT; the mobo’s audio is disabled via the bios.

Every few reboots jack will start ok, but I don’t understand why (though I’ve tried very hard to work it out!). Today I’ve rebooted a few times and jack just won’t fire up. Here’s the message output:

11:34:39.162 Patchbay deactivated. 11:34:39.164 Statistics reset. 11:34:39.304 ALSA connection graph change. 11:34:39.458 ALSA connection change. 11:34:40.844 JACK is starting... 11:34:40.846 /usr/bin/jackd -R -dalsa -dhw:0 -r44100 -p1024 -n2 no message buffer overruns jackd 0.116.1 Copyright 2001-2005 Paul Davis and others. jackd comes with ABSOLUTELY NO WARRANTY This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details JACK compiled with System V SHM support. loading driver .. apparent rate = 44100 creating alsa driver ... hw:0|hw:0|1024|2|44100|0|0|nomon|swmeter|-|32bit control device hw:0 11:34:40.903 JACK was started with PID=7543. ALSA: Cannot open PCM device alsa_pcm for playback. Falling back to capture-only mode cannot load driver module alsa 11:34:41.284 JACK was stopped successfully. 11:34:41.285 Post-shutdown script... 11:34:41.286 killall jackd jackd: no process found 11:34:41.750 Post-shutdown script terminated with exit status=256. 11:34:43.021 Could not connect to JACK server as client. - Overall operation failed. - Unable to connect to server. Please check the messages window for more info.

I’ve had problems where even though the onboard interface is disabled in the BIOS, it isn’t really disabled - it seems to simply mean that if a (Windows?) OS queries the BIOS to find out about the audio, the BIOS pretends the interface isn’t there. If you load a real OS like linux it finds the interface still sitting on the PCI bus and installs (or tries to install) drivers for it.
This then means that you can get plagued by the ALSA Audio Interface Muddle - where hw0 and hw1 are arbitarily assigned depending upon which driver module happens to get loaded first by the kernel, so you think you are starting JACK connected to the 1010 and you are really connecting it to the onboard audio driver.
If it fails again, try starting JACK with hw1 and see if it works.

linuxdsp you are a Genius! I set hw=1 in jack and off it went :smiley: All my headaches suddenly disappeared and all I see ahead is a bright weekend. It never crossed my mind that the bios may be faking it.

I remember in the mists of time there was a method of forcing hw:0 & hw:1 to stick to the same audio cards forever. Anyone remember how that routine works?

There are some config file changes you can make to force the hw0 / 1 config - I’ll have to go and look at how I configured my machine. I’ll post some more information when I have it.

There’s some information here which might be useful:

specifically this section

“How to choose a particular order for multiple installed cards”

I hope this is useful - I haven’t had to do this configuration on Ubuntu - my machine is running Mandriva so the config may be different but the principle is generally the same.

thank you, that page rings bells and I should be able to sort it out without further ado