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I have a problem when starting jack server, can you please help me find the solution?

$ tail -f ~/.log/jack/jackdbus.log
Sun Jan  8 18:55:14 2017: JACK server starting in realtime mode with priority 10
Sun Jan  8 18:55:14 2017: self-connect-mode is "Don't restrict self connect requests"
Sun Jan  8 18:55:14 2017: ERROR: Cannot lock down 82274202 byte memory area (Cannot allocate memory)
Sun Jan  8 18:55:14 2017: Acquired audio card Audio0
Sun Jan  8 18:55:14 2017: creating alsa driver ... hw:0|hw:0|1024|2|44100|0|0|nomon|swmeter|-|32bit
Sun Jan  8 18:55:14 2017: ERROR: ALSA: Cannot open PCM device alsa_pcm for playback. Falling back to capture-only mode
Sun Jan  8 18:55:14 2017: ERROR: Cannot initialize driver
Sun Jan  8 18:55:14 2017: ERROR: JackServer::Open failed with -1
Sun Jan  8 18:55:14 2017: ERROR: Failed to open server
Sun Jan  8 18:55:15 2017: Saving settings to 
"/home/home/.config/jack/conf.xml" ...
David Foerster
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Sugam
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1 Answers1

1

This error:

ERROR: ALSA: Cannot open PCM device alsa_pcm for playback.

gives me a hint of what might be going wrong.

In order to troubleshoot the jackd server, make first sure that ALSA is available and pulseaudio is switched off (or paused), to not grab and block the ALSA interface. Also, make sure the jackd server is no longer running, because that is also going to lock the ALSA interface.

You can try to play something directly on ALSA by loading a sound in audacity and selecting ALSA as an output in the preferences.

If this works, you can run jackd via CLI to see what output it creates, start simple, using the defaults

jackd -d alsa

Remember, ALSA is the low level sound card driver, it does not allow sharing, only one sound server can be using it at the same time, either pulseaudio or jack, but not both.

Markus Bawidamann
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