[PlanetCCRMA] Re: Problem with /usr/bin/jackstart

Ron Pepper feffer777@yahoo.com
Wed Aug 10 13:32:02 2005

--- Mark Knecht <markknecht@gmail.com> wrote:

> On 8/6/05, Ron Pepper <feffer777@yahoo.com> wrote:
> > --- Mark Knecht <markknecht@gmail.com> wrote:
> > 
> > > Right. You can see from the message above that it doesn't like
> n=4
> > > and
> > > sseems to want you to use n=2.
> > >
> > > In terms of latency, n=2/p=1024 is the same as n=4/p=512.
> > 
> > > So realtime is loaded but apparently your user account is not
> able
> > > to
> > > access the capability...
> > 
> > > I load realtime like this:
> > >
> > > modprobe realtime gid=408 any=1
> > >
> > > This grants group 408 the rights to use realtime capabilities.
> In
> > > my
> > > /etc/group file I have this line:
> > > realtime:x:408:mark
> > 
> > > which places user mark in group 408. With my laptop I can then
> run
> > > jackd -R
> > 
> > Thanks for breaking it down for me. So I added a group and then
> got:
> > [rp@localhost ~]$ jackd -d alsa -r 44100 -n 2 -p 1024 -d hw
> > result: a long string of "**** alsa_pcm: xrun of at least 0.031
> > msecs"
> Right, so without realtime capabilities your system needs to run
> with
> more latency. You would try 2/2048 or 2/4096, etc. I'm not saying
> these would be of any value in real life but rather it's jsut the
> way
> you'd get things to run without realtime and without xruns.
> Below why dod you switch beack to -n 4?????
> > 
> > Then tried:
> > [rp@localhost ~]$ jackd -d alsa -r 44100 -n 4 -p 1024 -d hw
> > jackd 0.99.36
> > 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
> > 
> > JACK compiled with System V SHM support.
> > `default' server already active
> > 
> > Does this mean jack is already running or that another sound
> server
> > is running and blocking it? When I then try to run xmms, I must
> quit
> > the terminal and use the ALSA plugin for output. The Jack plugin
> > freezes xmms when I try it.
> Yes, Jack was still running somewhere. This is not good and would
> have
> stopped JAck from starting if it was already running. You would run
> ps aux
> to see the process stack and then kill any jack processes that are
> running. Note that this may leave behind fifos in memory somewhere
> and
> still confuse JAck. If you're not reasy to clean all this stuff up
> by
> hand yet then possibly a reboot would be better for you.
> > 
> > > What confuses me about all of this is that I thought Fernando's
> > > scripts set all this up automatically...
> > 
> > My system is somewhat of a hybrid. When I first installed FC3, it
> > didn't recognize the soundcard. I found the ALSA site and finally
> > sorted out that I needed to configure a module for my "special"
> sound
> > chip. While struggling to do this, I was helped by Rick B. who
> also
> > pointed me to CCRMA. I then loaded a CCRMA kernel and pointed
> > Synaptic to Fernando's repositories. Since I finally got xmms etc
> > working, I was worried about tearing it all down again to install
> a
> > pure CCRMA system. I intend to do this at some point, but want to
> get
> > more familiar with CLI and Linux in general first. 
> There is no reason that I know of that would require you to do
> this.
> If Synaptic says this are set up correctly then they probably are.
> > Am I right in
> > thinking that I need to use Jack as my sound server in order to
> do
> > the dual activities of playing an audio-stream from xmms and
> > recording it?
> No, you have some terminology mixed up here:
> 1) Alsa is the sound server.
> 2) Alsa will only handle one client at a time so with Alsa running
> you
> can run alsaplayer OR xmms or mplater one at a time.
> 3) Jack is a way of connecting multiple audio apps to each other
> and
> to Alsa, but Jack is the only app that connects to Alsa so it's the
> 'one app' in #2 above.
> 4) Multiple apps can then connect to Jack. Jack does routing and
> summing so Jack makes Alsa think there is only one app and Jack
> routes
> all the Jackified audio from app to app.
> If you are running Gnome or KDE and start their sound server then
> you
> *may* get in the way of starting Alsa. It does not sound like you
> have
> this problem. Most of these sound servers support being an Alsa
> client
> these days but I find it best to not start them at all if possible,
> at
> least until you get the other stuff working correctly.
> I'm disappointed that no one else has stepped into this
> conversation.
> I feel that I must be overlooking some obvious PlanetCCRMA/FCx item
> that would make things work better for you. Unfortunately (for you)
> I
> do most of my audio on Gentoo now where set p is not so mysterious
> for
> me. Unfortunately that's not really a good option for someone newer
> to
> Linux. I did spend a few minutes looking through Fernando's
> installation instructions and admit I cannot see what you might
> have
> forgotten.
> Let's keep trying. 
> - Mark

Thanks for explaining details about the relationship between ALSA,
Jack and sound apps. I'm still somewhat concerned that my sound card
is even full duplex capable. I checked a couple of sites and it seems
my options are to ask the manufacturer (Creative or Dell) or to make
a test and play a stream and record it at the same time. Of course,
this is what I've been trying, but unable to do under FC3. Since the
machine dual boots with XP, I went to the windows side and tried to
play and record at the same time. Windows Sound Recorder wasn't
installed, so that may be a sign. Anyway, I downloaded a demo
recording app and made the test. The recorder seemed to "hear" the
audio (equilizer bars moved appropriately), but the resulting MP3 was
silent when played back. This was the same behaviour I got with FC3.
So now I'm really concerned that the on-board sound chip may only be
half-duplex. Is there any other test that anyone knows about to tell
me for sure?

Maybe my best next step would be to buy and install a new soundcard.
What do you think? If so what would be a good choice? I'm not
interested in high end audio like many of CCRMA's users, but only
good quality for listening to music while I work, and being able to 
play and record audio streams at the same time. 


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