[linux-audio-user] jack trouble

Chris Metzler cmetzler at speakeasy.net
Sun Mar 14 00:02:32 EST 2004


I'm coming into this late; and I'm just got started doing Linux audio
stuff fairly recently, so I could be worse than useless here; but
anyway . . .


On Wed, 10 Mar 2004 11:03:00 +0100
"C. Villard" <chvillard at wanadoo.fr> wrote:
>
> 
> So I'm trying to launch jack and, as root, I type #jackd -d alsa -r 
> 44100 and here is what I get :
> 
>     jackd 0.95.0
>     Copyright 2001-2003 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
>      
>     loading driver ..
>     apparent rate = 44100
>     creating alsa driver ...
>     hw:0|hw:0|1024|2|44100|0|0|nomon|swmeter|rt|32bit
>     control device hw:0
>     configuring for 44100Hz, period = 1024 frames, buffer = 2 periods
>     Couldn't open hw:0 for 32bit samples trying 24bit instead
>     Couldn't open hw:0 for 24bit samples trying 16bit instead
>     Couldn't open hw:0 for 32bit samples trying 24bit instead
>     Couldn't open hw:0 for 24bit samples trying 16bit instead
> 
> 
> And I'm obliged to do a Ctrl C to stop the process and Iget the mess :
> 
>     jack main caught signal 2

So, my question here is:  what's the problem?  This looks to me like
jackd started just fine.  You told it to talk to the ALSA driver and
to use a sample rate of 44100 Hz.  You didn't specify any other
parameters, so for those it used the default values.  The man page
for jackd says that it first tries 32-bit samples, bouncing down
to 16-bit samples if 32 or 24 aren't possible with the soundcard
you're using.  So it looks to me like it started just fine.  And that
message you got when you ctrl-c'd it ("jack main caught signal 2") is
what jackd always says when I ctrl-c it.  So, it looks like it started
just fine.


> 
> When switching verbose option for starting jack, jackd -vd alsa -r 
> 44100, I get also thiese lines :
		[ snip a lot of normal stuff ]
>     
>      
>     **** alsa_pcm: xrun of at least 0.912 msecs
>
>     **** alsa_pcm: xrun of at least 5.614 msecs
>
>     **** alsa_pcm: xrun of at least 27.009 msecs
>
>     **** alsa_pcm: xrun of at least 9.031 msecs

	[ with load stuff snipped ]

OK, so you're getting xruns.  But that doesn't say to me that jackd
isn't working -- merely that it's running suboptimally.

Or am I missing something here?

-c

-- 
Chris Metzler			cmetzler at speakeasy.snip-me.net
		(remove "snip-me." to email)

"As a child I understood how to give; I have forgotten this grace since I
have become civilized." - Chief Luther Standing Bear
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