[Ardour-Dev] Alsa works, Ardour/Jack fails

Patrick Shirkey pshirkey at boosthardware.com
Tue Jan 13 03:43:11 PST 2009

Mike Mazarick wrote:
>  Patrick Shirkey wrote:
>> This may be related to volume levels? Have you tried adjusting the
>> output of ardour or the alsamixer settings?
> Yes.   However,  I should mention that as a rule I'm testing this out by
> selecting the output on the 'Ardour Mixer' strip.  This works for the first
> 24 channels, but I get the 'bad guitar cord' effect on the last 4 channels. 
>> Also, have you tried using another jack app to playback audio to each
>> channel like alsaplayer for example?
> Aplay seems to work fine.  Of course, I don't have an 'ardour equivalent' so
> that I can determine if it is the driver or alsa/jack.
> Since the driver I'm using isn't in the alsa tree, all the 'normal stuff'
> has to be done by hand and I'm unsure if the RealTime is effective.   Using
> 'setpci' and giving the audio devices higher priority doesn't seem to have
> an impact.
> I am not completely familiar with the universe of Linux audio.   If there is
> another app which uses Jack to test this situation, 
alsaplayer -o jack somefile.wav

or there are several other mp3 players too like amarok and possibly 
there is also a jack_play app for testing. Or you could wrap aplay with 
the jack wrapper app but I currently forget it's name.

> it would greatly
> simplify things and help me figure out the driver vs jack vs ardour issue.
> Since Jack/Ardour works with RME and other cards, I'm thinking driver, but
> it would help if it was confirmed that it also worked with other sync'd
> cards like several Delta 1010s in a system.

Definitely. Several people have advanced setups like the above.
>> What you are doing with 4 synced sound cards is fairly unusual and if
>> you are using alsa dmix to run them as one card there could well be
>> some outstanding bugs in the driver You could also try running them in
> sync
>> with netjack.
> That's what I get for trying to 'kill two birds with one stone', providing
> QC on a driver by 'stress testing' it's limits and working up a new
> application.
> It becomes necessary to carefully craft the stone.
>> Are you using the plughw interface?
> In order to simplify this situation (and because I'm mainly interested in
> 'pro level' stuff rather than consumer), I make it a point to remove all
> pulseaudio stuff.   It may be useful at some point in the future for me
> (later), but there are configuration error messages that show up in the
> /var/log/messages file that are distracting.
plughw is the software managed hw interface for alsa which may allow 
smoother operations with multiple devices as one device setup whihc you 
are using.


jackd -d alsa -d plughw:0 -r 44100 -n2 -p 1024

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Patrick Shirkey
Boost Hardware Ltd.

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