ubuntu studio 10.04 and novation x-station - trying to record audio 1 and 2

[Pablo]

jay gallivan escribió:
> Thanks for your reply. I'm a total newbie to all of this.
Hi Jay,

Pulseaudio is a linux sound system (audio server) desktop oriented and 
Jack (Jack Audio Connection Kit) is another one, oriented towards music 
production (low latency, anything to anywhere connections...). Both use 
the alsa drivers (jack can also use the ffado drivers for firewire audio 
devices but this is not your case) but apart from that, they are very 
different beasts.

Timidity is a default midi server. It can do jack, but it doesn't by 
default. In a musical environment timidity is not as used as qsynth for 
example, which is "jackified" by default. But you must load a soundfont 
in qsynth.

In order to use Rosegarden (the audio part) you need the jack audio 
server and forget about pulseaudio interfaces (once jack takes hold of 
your soundcard, pulseaudio is useless, and, hopefully, harmless). You 
launch the server by means of a graphical front-end called qjackctl 
(Jack Control in the sound and video menu). First, you press "setup" to 
configure the jack audio server. In the interface field you select your 
usb audio card (you will see a generic usb-audio or similar, I guess). 
Then press start to activate jack.

If jack does not start, this is the first problem you should solve (more 
below).

If it starts, then the jack audio clients, like rosegarden, and many 
more (most music oriented programs are jack-aware by default) will show 
their ports in the connect window, audio tab, when you launch them.
The MIDI tab stands for jack MIDI which is not used by Rosegarden 
nowadays. The alsa tab refers to alsa  sequencer or alsa MIDI. It has 
nothing to do with jack but it is there for convenience because several 
synths and sequencers use the alsa sequencer for MIDI and jack for 
audio. Some newer ones use jack MIDI and jack audio but not Rosegarden.

This explains that you could capture midi in Rosegarden despite the jack 
server was not active.

Also, take into account that Rosegarden does not make sounds by itself 
and it has not any default synth that makes it work out of the box.. It 
needs either a software synth plugin or an external synth, either 
software (say, qsynth, zynaddsubfx...) or hardware.  But this is a 
second step. The first step is jack setup.

In order to have jack working in realtime mode (recommended) you need, 
as a user, some priorities that you can check in a terminal with:

ulimit -r (this is realtime priority for the user)
ulimit -l (this is memlock limit for the user)

You need the first one at ninety-something and the second one, unlimited 
or a reasonable amount of your RAM, in kB. In turn, to gain these 
privileges, there must be a file called:

/etc/security/limits.d/audio.conf

with the relevant lines. So please, do a:

cat /etc/security/limits.d/audio.conf

and you must have something like:

@audio - rtprio 99
@audio - memlock unlimited

Now you (you the user) have to belong to the "audio" group. Check in a 
terminal with:

groups

If you see audio (between others) you are done. If you don't, you must do:

sudo adduser user audio

where "user" is your login name. Then reboot and you will have the 
system prepared to use jack
(check again with the ulimit commands)



>
> I don't see anything in Patchbay. In PulseAudio Manager I see 
> X-Station analong stero as a sink and the same as sources for stereo 
> and stereo monitor.

Just don't use pulseaudio.
>
> When I connect (via Connect) X-Station to Timidity I am able to play 
> the keyboard and hear the results via my computer's speakers. And I 
> can record and playback via Rosegarden when I connect X-Station to 
> Rosegarden.
Don't use timidity unless you do it jack-aware.

>
> I've tried Audacity on my Windows XP box and I've been able to 
> pickup/record from the X-Station audio ports - though merged into a 
> single track for some reason.
>
> So it seems that the X-Station is doing what it's supposed to do. But 
> that (some component of ) Ubuntu Studio is dropping the X-Station 
> audio. Any thoughts on that?
See above.

Cheers! Pablo