Launch Jack Audio Connection Kit daemon with realtime scheduling

Today, it is very simple to launch the Jack Audio Connection Kit daemon with realtime scheduling, with a no-root user.
When Jack Audio Connection Kit is installed, it adds specific "limit" to jackuser group, into Pluggable Authentication Modules (pam).
Cf. the /etc/security/limits.conf file.

So the only need is to add the user which must need to launch the Jack Audio Connection Kit daemon with realtime scheduling into the jackuser group:
/usr/sbin/usermod -G jackuser "username"

Then, use the -R option when launching Jack Audio Connection Kit daemon:
jackd -R ...

N.B.: those instructions have been performed (at least) under Fedora 8

Use MIDI software "soundfonts mapping"

This is a quick "how to", to use softwares installed like explained on this post:
- launch Jack Audio Connection Kit daemon with options according to your configuration (let's said you are using ALSA)
jackd -R -d alsa
The -R option is used for "real-time", I explain it into my next post.
- launch a fluidsynth GUI frontend
qsynth
- setup the wished soundfonts (there we're using the path of the fluid R3 soundfonts), setup->Soundfonts->Open and selects the path /usr/share/soundfonts/FluidR3_GM.SF2 (under Fedora 8),
- finally launch Rosegarden and play MIDI files or Rosegarden Studio of your choice
rosegarden
- you may need to update configuration of the MIDI devices, Studio->Manage MIDI devices.

N.B.: those instructions have been performed (at least) under Fedora 8

Setup MIDI software "soundfonts mapping" (instead of hardware)

In this post, I've (quickly) explained how to set up environment to play MIDI file, loading soundfonts into wavetable of the sound card.
Nevertheless, the soundfonts which can be loaded into the sound card is obviously limited to available memory and so compromise must be done between quality and size.

Instead of this, it is possible to use software "soundfonts mapping". Today, there is lots of very powerful and mature softwares although all must be set up with caution to avoid latency issue.
There is various interesting explanations on the subject, for instance Planet CCRMA at home, and Linux MAO.

This is the software which an be used (prefixed by corresponding package name under Fedora):
- jack (Jack Audio Connection Kit): a low-latency audio server,
- qjackctl: a simple application to control the JACK sound server,
- fluidsynth: a real-time software synthesizer based on the SoundFont 2 specifications,
- qsynth: a fluidsynth GUI front-end application,
- fluid-soundfont-R3: fluid R3 soundfonts of good quality,
- rosegarden4: a professional audio and MIDI sequencer, score editor, and general purpose music composition and editing environment.

N.B.: those instructions have been performed (at least) under Fedora 8

Prepare Fedora environment to become an audio plateform

After some search of interesting tools to play midi musics (with external devices) under GNU/Linux, I finally find an unbelievable project: Planet CCRMA at home.
They provide all needed packages for updating an environment "to transform it into an audio workstation with a low-latency kernel".

There is rich installation information on the official site.

My first aim is to discover the astonishing features of Rosegarden.
To get it fully installed, I have had to install some additional packages XML::Twig and LilyPond:
yum install perl-XML-Twig lilypond

Currently the real-time kernel does not boot on my computer, I'll surely post information about this later ...

N.B.: those instructions have been performed (at least) under Fedora 8

Play MIDI under GNU/Linux with ALSA

There is lots of articles on the subject but it is not so trivial to get needed information to use ALSA tools to play MIDI files.

This is some quick information:
- the first is obviously to have a working ALSA installation,
- if you have several sound cards, ensure the default is well the wanted one (for instance using system-config-soundcard under Fedora),
- then it is important to ensure not having mute channel(s), you can use alsamixer for this,
- then ensure to have a way to load soundfonts into the wavetable of the sound card; for instance of sound card managed AWE32/Emu10k1 sound driver, you can install the awesfx package
yum install awesfx
- get a soundfonts to load, for instance this one,
- at any moment, to check if there is a loaded soundfonts:
cat /proc/asound/card?/wavetableD?
- you can clear currently loaded soundfounts but you want to keep it:
/bin/asfxload -i
- then load it:
/bin/asfxload "soundfonts file path"
- find the "addresses" into the "/proc/asound/card?/wavetableD?" file (for instance: 17:0 17:1 17:2 17:3),
- finally test installation using aplaymidi to play a MIDI file
aplaymidi -p "addresses"* "MIDI file path"
* addresses must be coma separated, 17:0,17:1,17:2,17:3 for instance.