Re: [Jack-Devel] adjusting default settings installed in ubuntu studio

Le Fri, 01 Jun 2012 19:22:47 -0500,
Scottalavender <[hidden]> a écrit :

> 
> 
> 
> Sent via the Samsung Galaxy S™ II Skyrocket™, an AT&T 4G LTE
> smartphone.
> 
> -------- Original message --------
> Subject: Re: Re: [Jack-Devel] adjusting default settings installed in
> ubuntu studio From: [hidden] 
> To: Scott Lavender <[hidden]> 
> CC: [hidden] 
> 
> On , Scott Lavender <[hidden]> wrote:
> > i to improve the "out of the box" performance by adjusting these
> > settings.
> 
> All the settings are available from the QJackCtl "setup" dialog. Also
> you can start jackd from the command line if you prefer.
> 
> $ jackd -h for info on how to do that.
> 
> There's no need to modify packages for changing the frames / buffers
> etc :D -Harry
> 
> Harry, I am quite capable of adjusting the setting for my computer.
> However as project lead for Ubuntu Studio I want to moderate the
> installed setting for the default installation in order to improve
> the "out the box performance".

For me, the ideal setting is to run jack all the time. For this to work
with every sound related software, I thing that the best way to
archive that is to load snd-aloop as first sound card. That way, all
the alsa only sound software will use aloop as default, a simple
script, launched by qjacjctl, will connect this virtual alsa device with
jack in full duplex:
( http://linuxaudio.org/mailarchive/lau/2012/4/4/189446 )
With such a setting, I am able to get ride of all the audio layers like
pulseaudio. It just work. A big applaud and thank you to the
developers that made it possible!

A simple ~/.asoundrc can be included into the skeleton for new users.
In my case, it is as simple than:

cat ~/.asoundrc
# playback PCM device: using loopback subdevice 0,0
pcm.amix {
  type dmix
  ipc_key 219345
  slave.pcm "hw:Loopback,0,0"
}

# capture PCM device: using loopback subdevice 0,1
pcm.asnoop {
  type dsnoop
  ipc_key 219346
  slave.pcm "hw:Loopback,0,1"
}

# duplex device combining our PCM devices defined above
pcm.aduplex {
  type asym
  playback.pcm "amix"
  capture.pcm "asnoop"
}

# ------------------------------------------------------
# for jack alsa_in and alsa_out: looped-back signal at other ends
pcm.ploop {
  type plug
  slave.pcm "hw:Loopback,1,1"
}

pcm.cloop {
  type dsnoop
  ipc_key 219348
  slave.pcm "hw:Loopback,1,0"
}

# ------------------------------------------------------
# default device

pcm.!default {
  type plug
  slave.pcm "aduplex"
}

I really think this is the best setup for a pro-audio environment
where a bridge between jack and alsa is needed.

The script launched by qjackctl after jackd(bus) start:
cat ~/bin/loop2jack
#!/bin/sh
# Launch the wanted software after jackd start.
# Usage: loop2jack sample_rate
# where sample_rate is jackd sample rate
# To launch it from qjackctl:
# loop2jack %r

## launch and configure the ALSA <-> JACK bridge
# clients creation
/usr/bin/alsa_out -j ploop -dploop -q 1 2>&1 1> /dev/null &
/usr/bin/alsa_in -j  cloop -dcloop -q 1 2>&1 1> /dev/null &

# 1 second wait before connection of the ports
sleep 1

# cloop ports -> jack output ports 
jack_connect cloop:capture_1 system:playback_1
jack_connect cloop:capture_2 system:playback_2

# jack input ports -> ploop
jack_connect system:capture_1 ploop:playback_1
jack_connect system:capture_2 ploop:playback_2

## You can add whatever else is needed here:
## Timidity++ in server mode
# TODO: launch timidity only if it is not running.
timidity -iA -B2,8 -Oj -EFreverb=0 -s $1 2>&1 1> /dev/null &

# done
exit 0


-- 
"We have the heroes we deserve."

1338643040.14576_0.ltw:2,a <20120602151959.2ba8780e at tuxstudio>