The Linux MIDI-HOWTO
By Phil Kerr, phil@plus24.com
v1.20, May 2002
This document describes the hardware, software and procedures needed
to play and sequence using MIDI under Linux.
______________________________________________________________________
Table of Contents
1. Introduction.
2. Copyright of this document.
3. Where to get this document.
4. Acknowledgments.
5. Disclaimer.
6. Background to MIDI.
7. Configuring MIDI devices.
7.1 ALSA 0.9 quick install
7.2 Latency
8. Software.
8.1 Drivers
8.1.1 Alsa Driver
8.1.2 OSS
8.1.3 Notemidi
8.2 MIDI file players
8.2.1 KMid
8.2.2 Pmidi
8.2.3 TiMidity++
8.3 Sequencers
8.3.1 Brahms
8.3.2 Anthem
8.3.3 Jazz++
8.3.4 Linux Ultimate Music Editor
8.3.5 Melys
8.3.6 MidiMountain Sequencer
8.3.7 MusE
8.3.8 Rosegarden
8.4 MIDI Trackers
8.4.1 tektracker
8.4.2 ShakeTracker
8.5 Drum editors
8.5.1 DrumPatterns
8.6 Patch editors
8.6.1 JSynthLib
8.7 Software synths
8.7.1 Spiral Synth
8.7.2 UltraMaster Juno-6
8.7.3 Pure-Data (PD)
8.7.4 Csound
8.7.5 Bristol synthesiser emulator
8.8 Plugins
8.8.1 xmms-midi
8.9 Notation
8.9.1 Mup
8.9.2 Lilypond
8.10 Development
8.10.1 sfront
8.10.2 jMax
8.10.3 TSE3
8.10.4 KeyKit
9. MIDI Development.
9.1 Example 1
9.2 Example 2
9.3 Example 3
10. HOWTO Use MIDI Sequencers With Softsynths.
10.1 Introduction
10.2 Device Setup
10.3 Routing MIDI Events
10.3.1 aconnect
10.4 Graphical MIDI Patch Bays
10.4.1 aseqview
10.5 Applications
10.6 Sequencers
10.6.1 MusE
10.6.2 ttrk
10.6.3 Shaketracker
10.7 Software Synthesizer
10.7.1 Pure Data
10.7.2 Csound
10.7.3 Conclusion
10.8 Acknowledgments
11. Useful Links.
12. Feedback.
______________________________________________________________________
1. Introduction.
It covers:
· Configuring your MIDI interface
· Configuring and using softsynths
· Playing MIDI files
· Sequencing
· Controlling external MIDI equipment
· MIDI controlled software based sound synthesis
· Example MIDI code
2. Copyright of this document.
This HOWTO is copyrighted 2002 Phil Kerr.
The 'HOWTO Use MIDI Sequencers With Softsynths' is copyright 2002
Frank Barknecht.'
This document is distributed under the terms of the GNU Free
Documentation License. You should have received a copy along with it.
If not, it is available from:
<http://www.fsf.org/licenses/fdl.html>.
3. Where to get this document.
The official version of this document can be obtained from the Linux
Documentation Project: <http://www.tldp.org/>.
The homepage for the most recent version of this HOWTO is:
<http://www.midi-howto.com>
4. Acknowledgments.
This HOWTO is an expansion of the MIDI-SB mini-HOWTO written by Hideki
Saito. Many thanks for his contribution to the Linux community.
This HOWTO now contains Frank Barknecht's 'HOWTO Use MIDI Sequencers
With Softsynths'. Many thanks Frank.
Many of the code samples contained in this HOWTO originated from the
Linux Audio Developers (LAD) mailinglist. Many thanks to them for
allowing their inclusion.
5. Disclaimer.
Use the information in this document at your own risk.
I disavow any potential liability for the contents of this document.
Use of the concepts, examples, and/or other content of this document
is entirely at your own risk.
All copyrights are owned by their owners, unless specifically noted
otherwise.
Use of a term in this document should not be regarded as affecting the
validity of any trademark or service mark.
Naming of particular products or brands should not be seen as
endorsements.
You are strongly recommended to take a backup of your system before
major installation and backups at regular intervals.
6. Background to MIDI.
MIDI is a set of hardware and software protocols used by electronic
musical instruments to communicate. It was first released in 1982
and has become the de-facto communication standard between electronic
musical instruments. The protocol specifies the physical hardware
parameters for the cable and interfaces, and provides a well defined
set of communication protocols to exchange musical and timing data.
Prior to MIDI there were several analog, and later basic digital,
connection protocols. The earliest, circa. 1974, would transmit note
information as a voltage though a wire from one keyboard to another.
Later, 1980 - 1981, Roland created a basic digital protocol, DCB.
The MIDI Manufacturers Association (MMA), working with the equipment
manufacturers, defined a standard protocol and physical connection
which allowed equipment from all complying manufacturers to connect
and communicate with each other.
>From 1985 MIDI interfaces started to appear on home computers and
soon after sequencing programs appeared.
7. Configuring MIDI devices.
MIDI devices can be integrated into the soundcard or be a separate
device. External MIDI interfaces may be attached to either the serial
or USB port.
The first *and most important* thing you should do is check if your
card is supported!
<http://www.alsa-project.org/soundcards.php3>
<http://www.4front-tech.com/osshw.html>
Configuring MIDI devices varies with Linux distributions. A well
supported card may be configured when you install the OS.
The Linux kernel includes the OSS drivers and in the 2.5 kernel the
ALSA drivers. Most distributions provide a configuration tool (mostly
for soundcards), but if you are using the MIDI port of a sound card it
should be configured. Under RedHat you would use sndconfig, under
SuSE yast, and Mandrake, DrakConf.
If none of the above tools will configure your MIDI interface, or you
are experiencing problems, the following steps should be taken:
Does lsmod show any MIDI related modules? Here's a typical output
from an OSS based system.
______________________________________________________________________
[root@beatbox]# lsmod
Module Size Used by
lockd 32208 1 (autoclean)
sunrpc 54640 1 (autoclean) [lockd]
autofs 9456 2 (autoclean)
usb-ohci 12624 0 (unused)
usbcore 43632 1 [usb-ohci]
hisax 470096 0 (autoclean) (unused)
isdn 104208 0 (autoclean) [hisax]
slhc 4544 0 (autoclean) [isdn]
eepro100 16144 1 (autoclean)
#---- Soundcard modules
opl3 11376 2
mad16 7968 1
ad1848 16848 1 [mad16]
sb 34752 1 [mad16]
uart401 6384 1 [mad16 sb]
sound 58368 0 [opl3 mad16 ad1848 sb uart401]
soundlow 464 0 [sound]
soundcore 2800 6 [sb sound]
nls_cp437 3952 2 (autoclean)
vfat 9408 1 (autoclean)
fat 30432 1 (autoclean) [vfat]
ide-scsi 7664 0
______________________________________________________________________
Look for mpu401, olp3, uart401 and oss.
If you are using USB devices don't forget to check if the USB modules
are there.
To check the config cat the sndstat file:
______________________________________________________________________
[root@beatbox]# cat /dev/sndstat
OSS/Free:3.8s2++-971130
Load type: Driver loaded as a module
Kernel: Linux mega 2.2.17-21mdk #1 Thu Oct 5 13:16:08 CEST 2000 i686
Config options: 0
Installed drivers:
Card config:
Audio devices:
0: MAD16 WSS (82C930) (DUPLEX)
Synth devices:
0: Yamaha OPL3
Midi devices:
0: Mad16/Mozart
Timers:
0: System clock
Mixers:
0: MAD16 WSS (82C930)
______________________________________________________________________
We see here that the MIDI device is a mad16 and this is listed in the
lsmod output above.
If you see nothing related to MIDI check the contents of your
/etc/modules.conf file.
______________________________________________________________________
[root@beatbox]# cat /etc/modules.conf
alias net-pf-4 ipx
pre-install pcmcia_core /etc/rc.d/init.d/pcmcia start
alias usb-interface usb-ohci
alias parport_lowlevel parport_pc
alias block-major-11 scsi_hostadapter
pre-install plip modprobe parport_pc ; echo 7 > /proc/parport/0/irq
alias scsi_hostadapter ide-scsi
alias eth0 eepro100
alias eth1 hisax
#---- Soundcard
alias sound-slot-0 mad16
options sound dmabuf=1
alias midi opl3
options opl3 io=0x388
options sb support=1
options mad16 io=0x530 irq=5 dma=0 dma16=1 mpu_io=0x300 mpu_irq=7 joystick=1
______________________________________________________________________
Here's the output of /proc/modules to check to see if the MIDI modules
are loaded into the Kernel.
______________________________________________________________________
[root@mega /proc]# cat modules
0000-001f : dma1
0020-003f : pic1
0040-005f : timer
0060-006f : keyboard
0070-007f : rtc
0080-008f : dma page reg
00a0-00bf : pic2
00c0-00df : dma2
00f0-00ff : fpu
0170-0177 : ide1
01f0-01f7 : ide0
02f8-02ff : serial(auto)
#---- MIDI device
0300-0303 : MPU-401 UART
0376-0376 : ide1
0388-038b : Yamaha OPL3
03c0-03df : vga+
03f6-03f6 : ide0
03f8-03ff : serial(auto)
0530-0533 : MAD16 WSS config
0534-0537 : MAD16 WSS
de00-de1f : Intel Speedo3 Ethernet
f000-f007 : ide0
f008-f00f : ide1
______________________________________________________________________
You should see something similar to the above. If not you'll need to
install MIDI drivers.
If you are going to be using ALSA 0.5x divers, which you shouldn't do,
I suggest a good read of Valentijn Sessink's Alsa-sound-mini-HOWTO
which can be found at the link below:
<http://www.linuxdoc.org/HOWTO/mini/Alsa-sound.html>
You are strongly recommended to use ALSA greater than version 0.9.
For ALSA drivers later than 0.9x you should have a good read of the
ALSA-HOWTO by Madhu Maddy.
<http://www.alsa-project.org/alsa-doc/alsa-howto/>
7.1. ALSA 0.9 quick install
Below is a very quick install run-though for installing the ALSA 0.9
drivers and libs which is a required configuration for most MIDI apps.
______________________________________________________________________
[root@beatbox] # tar jxvf alsa-driver....tar.bz2
[root@beatbox] # cd alsa-driver.....
[root@beatbox] # ./configure
messages - no errors
[root@beatbox] # make
messages - no errors
[root@beatbox] # make install
messages - no errors
[root@beatbox] # ./snddevices
______________________________________________________________________
Now you will need to edit /etc/modules.conf, or the ALSA file in your
modules directory on some distributions. There may be entries for
other, non-MIDI, devices, so be careful when you are editing the file.
A typical system may have old ALSA or OSS configurations in the file,
you will need to remove, or better still comment them out.
Below is a typical modules.conf file showing the ALSA config with OSS.
______________________________________________________________________
alias char-major-116 snd
alias char-major-14 soundcore
alias snd-card-0 (MIDI/Sound card)
alias sound-slot-0 snd-card-0
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-12 snd-pcm-oss
______________________________________________________________________
Change the (MIDI/Sound card) entry to that of your card. This
information can normally be found on the ALSA website.
With the ALSA drivers installed, now you will need to install the
header library files needed by ALSA based programs. This is what is
contained in the alsa-libs package.
Make sure you have a matching pair of alsa-drivers and alsa-libs!
______________________________________________________________________
[root@beatbox] # tar jxvf alsa-libs....tar.bz2
[root@beatbox] # cd alsa-libs.....
[root@beatbox] # ./configure
messages - no errors
[root@beatbox] # make
messages - no errors
[root@beatbox] # make install
______________________________________________________________________
Your system should now be configured :)
You can check this with a simple C program, if it compiles and can be
executed then your system should be ok.
______________________________________________________________________
// Compile this test program like so: gcc alsatest.c -o alsatest -lasound
#include <stdio.h>
#include <alsa/asoundlib.h>
int main (int argc, char *argv[])
{
snd_seq_t *seq_handle;
if (snd_seq_open(&seq_handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
fprintf(stderr, "Error opening ALSA sequencer.\n");
exit(1);
}
printf("The ALSA libraries are installed.\n");
return 0;
}
______________________________________________________________________
7.2. Latency
MIDI is a real-time protocol and latency issues are a serious problem.
There are now several developers working on improving the latency
times and improvements in the kernel are making Linux a fine platform
for MIDI.
Although stock Linux distributions may run fine, pro set-ups should
apply low-latency patches. More information can be found here:
<http://www.gardena.net/benno/linux/audio/>
<http://www.linuxdj.com/audio/lad/resourceslatency.php3>
Low Latency Mini Howto
<http://www.boosthardware.com/LAU/guide/Low_latency-Mini-HOWTO.html>
8. Software.
Interest in Linux based MIDI is growing and this list will probably
not reflect the true amount of MIDI software available, but should
provide a reasonable selection of applications.
If you are developing, or know of, any other MIDI apps not listed here
please drop me a note.
8.1. Drivers
8.1.1. Alsa Driver
The Advanced Linux Sound Architecture is composed of several parts.
The first is a fully modularized sound driver which supports module
autoloading, devfs, isapnp autoconfiguration, and gives complete
access to analog audio, digital audio, control, mixer, synthesizer,
DSP, MIDI, and timer components of audio hardware. It also includes a
fully-featured kernel-level sequencer, a full compatibility layer for
OSS/Free applications, an object-oriented C library which covers and
enhances the ALSA kernel driver functionality for applications
(client/server, plugins, PCM sharing/multiplexing, PCM metering,
etc.), an interactive configuration program for the driver, and some
simple utilities for basic management.
<http://www.alsa-project.org/>
8.1.2. OSS
OSS provides sound card drivers for most popular sound cards under
Linux and FreeBSD. These drivers support digital audio, MIDI,
synthesizers, and mixers found on sound cards. These sound drivers
comply with the Open Sound System API specification. OSS provides a
user-friendly GUI which makes the installation of sound drivers and
configuration of sound cards very simple. It supports over 200 brand
name sound cards, and provides automatic sound card detection, Plug-n-
Play support, support for PCI audio soundcards, and support for full
duplex audio.
<http://www.opensound.com/>
8.1.3. Notemidi
Notemidi is a device driver for MIDI output via the RS-232 serial port
on notebook/laptop computers. Notemidi can be used with the MIDIator
MS-124W interface, Roland Sound Canvas sound modules, or Yamaha MU-x
series sound modules.
<http://www.michaelminn.com/linux/notemidi>
8.2. MIDI file players
8.2.1. KMid
KMid is an X11 / KDE based midi player for Linux and FreeBSD. It
displays the text of karaoke files and changes its colour as it is
being played so that the tune can be easily followed. KMid uses
/dev/sequencer as output device supporting external synths, AWE , FM
and GUS cards.
<http://perso.wanadoo.es/antlarr/kmid.html>
8.2.2. Pmidi
Pmidi is a straightforward command line program to play Midi files
through the ALSA sequencer.
<http://www.parabola.demon.co.uk/alsa/pmidi.html>
8.2.3. TiMidity++
TiMidity is a MIDI to WAVE converter that uses Gravis
Ultrasound(*)-compatible patch files to generate digital audio data
from General MIDI files. The audio data can be played through any
sound device or stored on disk. On a fast machine, music can be played
in real time.
<http://www.goice.co.jp/member/mo/timidity/>
8.3. Sequencers
8.3.1. Brahms
Brahms is a sequencer and music notation program with several editing
methods so far including Score-, Pianoroll-, Drum-, and Mastertrack
Editors. For C++ programmers, it is easy to implement further editors
by deriving from a general editor-class. MIDI Import and Export is
also implemented. In combination with aRts-0.3.4, one can play wave-
files and make use of the midibus to send midi-events to the software
synthesizer.
Formerly known as KooBase
<http://brahms.sourceforge.net/>
8.3.2. Anthem
Anthem is an advanced open source MIDI sequencer. Anthem allows you to
record, edit and playback music using a sophisticated and acclaimed
object oriented song technology.
<http://anthem.sourceforge.net/>
8.3.3. Jazz++
JAZZ++ is a full featured, audio capable midi sequencer for Linux and
Windows.
<http://www.jazzware.com/cgi-bin/Zope.cgi/jazzware/>
8.3.4. Linux Ultimate Music Editor
UltiMusE-LX (the Ultimate Music Editor) is a composing program. No, it
doesn't compose for you; it's a "word processor" for music. You draw
sheet music on the screen using the mouse and/or computer keyboard. Up
to 16 parts or voices fit on up to seven staves (staffs). Most
standard musical notations are supported, as are MIDI instrument patch
changes, events, and real-time clocks.
<http://hometown.aol.com/knudsenmj/myhomepage/umuselx.htm>
8.3.5. Melys
Melys is a Midi sequencer application for the Advanced Linux Sound
Architecture (ALSA). Melys uses the sequencer support of ALSA, along
with the GNOME libraries to produce a powerful and easy to use
sequencer.
<http://www.parabola.demon.co.uk/melys/>
8.3.6. MidiMountain Sequencer
MidiMountain is a sequencer to edit standard MIDI files. Its easy-to-
use interface should help beginners to edit and create MIDI songs
(sequences), and it is designed to edit every definition known to
standard MIDI files and the MIDI transfer protocol, from easy piano
roll editing to changing binary system exclusive messages.
<http://www.midimountain.com/>
8.3.7. MusE
MusE is a Qt 2.1-based MIDI sequencer for Linux with editing and
recording capabilities. While the sequencer is playing you can edit
events in realtime with the pianoroll editor or the score editor.
Recorded MIDI events can be grouped as parts and arranged in the
arrange editor.
<http://muse.seh.de/>
8.3.8. Rosegarden
Rosegarden is an integrated MIDI sequencer and musical notation
editor.
<http://www.all-day-breakfast.com/rosegarden/>
8.4. MIDI Trackers
8.4.1. tektracker
ttrk (tektracker) is a console MIDI sequencer with a tracker-style
step editor. It is built for live playing, with convenient track mute
buttons and loop control. ttrk supports both sending and syncing to
MIDI clock pulses.
<http://div8.net/ttrk/>
8.4.2. ShakeTracker
ShakeTracker aims to be a fully-featured MIDI sequencer with a tracker
interface. It currently works well and supports most tracker effects.
Anyone who has used Impulse Tracker before will feel at home, and for
the new users, a simple but extensive help system is provided. Most
commands and shortcuts resemble their tracker counterparts.
<http://reduz.com.ar/shaketracker/>
8.5. Drum editors
8.5.1. DrumPatterns
DrumPatterns is a free, open source, web oriented drum patterns
generator, whose purpose is to help teach drum patterns. It can teach
the rudiments as well as advanced rhythms. It can output characters,
score, or Midi, and includes hours of samples.
<http://www.linux-france.org/prj/drumpatterns/index-en.html>
8.6. Patch editors
8.6.1. JSynthLib
JSynthLib is an Open Source Universal Synthesizer Patch Editor /
Librarian written in the Java Language. The project aims to eventually
provide support for all existing Synthesizers by providing methods and
documentation which allow users to develop drivers and editors for
unsupported synths and contribute them to the project.
8.7. Software synths
8.7.1. Spiral Synth
Spiral Synth is a physically modeled polyphonic analogue synthesizer.
It is capable of creating the kind of sounds made by hardware analogue
synths, the noises used in electronic music. You can also use it to
make stranger sounds too. MIDI is supported, and it uses the standard
OSS/Free sound output (/dev/dsp).
<http://www.pawfal.org/SpiralSynth/>
8.7.2. UltraMaster Juno-6
UltraMaster Juno-6 is a faithful virtual reproduction of a Roland
Juno-6 Polyphonic Synthesizer. It features realtime 64-bit internal
ULTRANALOG wave synthesis, an early 80's style arpeggiator and chorus,
and 100s of patches to save your own custom settings. All parameters
can be controlled in realtime, via on-screen GUI or external MIDI
controllers.
<http://www.ultramaster.com/juno6/index.html>
8.7.3. Pure-Data (PD)
"Pd" stands for "pure data". Pd is a real-time software system for
live musical and multimedia performances. It is in active development
by Miller Puckette , and perhaps others. The system is unfinished, but
quite useable for sophisticated projects. It has been ported to Linux,
IRIX, and many flavors of Windows.
<http://www.pure-data.org/>
8.7.4. Csound
Csound is a software synthesis program. But more than that, Csound
doesn't suffer the same kinds of limitations that other software &
hardware synthesizers have. There are no limits to the amount of
oscillators or filters one can use. Csound is also completely modular,
so that any function in Csound can be used in an array of ways.
<http://www.csound.org/>
8.7.5. Bristol synthesiser emulator
Bristol is a synthesizer emulation package. It includes a Moog Mini,
Moog Voyager, Hammond B3, Prophet 5, Juno 6, DX 7, and others.
<http://www.slabexchange.org/index.cgi?DOWNLOAD>
8.8. Plugins
8.8.1. xmms-midi
Adds midi file support for x11amp (via timidity). A crude mixer
interface is provided via the configuration dialog.
<http://ban.joh.cam.ac.uk/~cr212/xmms-midi/>
8.9. Notation
8.9.1. Mup
Mup takes a text file as input and produces PostScript output for
printed music. It can handle both regular notation and tablature
notation. (It can also produce MIDI output.)
<http://www.arkkra.com/>
8.9.2. Lilypond
LilyPond is a music typesetter. It produces beautiful sheet music
using a high level description file as input. LilyPond is part of the
GNU Project.
<http://www.lilypond.org/>
8.10. Development
8.10.1. sfront
Sfront compiles MPEG 4 Structured Audio (MP4-SA) bitstreams into
efficient C programs that generate audio when executed. MP4-SA is a
standard for normative algorithmic sound, that combines an audio
signal processing language (SAOL) with score languages (SASL, and the
legacy MIDI File Format). Under Linux, sfront supports real-time, low-
latency audio input/output, local MIDI input from soundcards, and
networked MIDI input using RTP and SIP. A SIP server hosted on the
Berkeley campus manages sessions. The website includes an online book
about MP4-SA.
<http://www.cs.berkeley.edu/~lazzaro/sa/index.html>
8.10.2. jMax
jMax allows one to interactively design dataflow circuits. The basic
data types that can go through are integers, symbols, lists, etc. It
is an event-driven system and has been used for MIDI processing. A
second part of the system (DSP) allows a continuous signal to flow
through a circuit, which is most useful for PCM sound (ie. microphone,
sound files, etc). The system is extensible by using shared libraries,
you may add data processor types, data types, GUI elements, device
types, and more. Data processors may also be designed as circuits and
reused.
<http://www.ircam.fr/equipes/temps-reel/jmax/>
8.10.3. TSE3
TSE3 is a powerful open source sequencer engine written in C++. It is
a 'sequencer engine' because it provides the actual driving force
elements of a sequencer but provides no form of user interface.
Sequencer applications or multimedia presentation packages will
incorporate the TSE3 libraries to provide a user with MIDI sequencing
facilities.
<http://TSE3.sourceforge.net/>
8.10.4. KeyKit
KeyKit is a multi-tasking interpreted programming language (inspired
by awk) designed exclusively for realtime and algorithmic MIDI
manipulation. KeyKit's GUI provides several dozen tools for
algorithmic music experimentation, including a multi-track sequencer
and drum pattern editor. The GUI and all tools are completely written
in the KeyKit language itself. This allows users to add new tools and
operations to the existing tools, even while the system is running.
<http://nosuch.com/keykit/>
9. MIDI Development.
For those looking to develop MIDI applications, good examples are
often needed to get you started.
The following examples were posted to the LAD mailing list in a thread
about examples and documentation/tutorials.
9.1. Example 1
Below is a little sequencer routine from Dr. Matthias Nagorni. More
examples can be obtained from Matthias's site which is listed in the
Links section.
You compile it like so:
______________________________________________________________________
[phil@beatbox] $ gcc seqdemo.c -o seqdemo -lasound
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <alsa/asoundlib.h>
snd_seq_t *open_seq();
void midi_action(snd_seq_t *seq_handle);
snd_seq_t *open_seq() {
snd_seq_t *seq_handle;
int portid;
if (snd_seq_open(&seq_handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
fprintf(stderr, "Error opening ALSA sequencer.\n");
exit(1);
}
snd_seq_set_client_name(seq_handle, "ALSA Sequencer Demo");
if ((portid = snd_seq_create_simple_port(seq_handle, "ALSA Sequencer Demo",
SND_SEQ_PORT_CAP_WRITE|SND_SEQ_PORT_CAP_SUBS_WRITE,
SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {
fprintf(stderr, "Error creating sequencer port.\n");
exit(1);
}
return(seq_handle);
}
void midi_action(snd_seq_t *seq_handle) {
snd_seq_event_t *ev;
do {
snd_seq_event_input(seq_handle, &ev);
switch (ev->type) {
case SND_SEQ_EVENT_CONTROLLER:
fprintf(stderr, "Control event on Channel %2d: %5d \r",
ev->data.control.channel, ev->data.control.value);
break;
case SND_SEQ_EVENT_PITCHBEND:
fprintf(stderr, "Pitchbender event on Channel %2d: %5d \r",
ev->data.control.channel, ev->data.control.value);
break;
case SND_SEQ_EVENT_NOTEON:
fprintf(stderr, "Note On event on Channel %2d: %5d \r",
ev->data.control.channel, ev->data.note.note);
break;
case SND_SEQ_EVENT_NOTEOFF:
fprintf(stderr, "Note Off event on Channel %2d: %5d \r",
ev->data.control.channel, ev->data.note.note);
break;
}
snd_seq_free_event(ev);
} while (snd_seq_event_input_pending(seq_handle, 0) > 0);
}
int main(int argc, char *argv[]) {
snd_seq_t *seq_handle;
int npfd;
struct pollfd *pfd;
seq_handle = open_seq();
npfd = snd_seq_poll_descriptors_count(seq_handle, POLLIN);
pfd = (struct pollfd *)alloca(npfd * sizeof(struct pollfd));
snd_seq_poll_descriptors(seq_handle, pfd, npfd, POLLIN);
while (1) {
if (poll(pfd, npfd, 100000) > 0) {
midi_action(seq_handle);
}
}
}
______________________________________________________________________
9.2. Example 2
Below is a ALSA 0.9 MIDI redirector by Nick Dowell.
______________________________________________________________________
/* ALSA Sequencer MIDI redirector.
Redirects the input to outputs determined by the MIDI channel
(as requested by Nathaniel Virgo on Linux-Audio-Dev ;-)
based on Dr. Matthias Nagorni's ALSA seq example
Nick Dowell <nixx@nixx.org.uk>
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <alsa/asoundlib.h>
int
main()
{
snd_seq_t *seq_handle;
snd_seq_event_t *ev;
int i;
int portid; /* input port */
int oportid[16]; /* output ports */
int npfd;
struct pollfd *pfd;
char txt[20];
if (snd_seq_open(&seq_handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
fprintf(stderr, "Error opening ALSA sequencer.\n");
exit(1);
}
snd_seq_set_client_name(seq_handle, "MIDI Redirect");
/* open one input port */
if ((portid = snd_seq_create_simple_port
(seq_handle, "Input",
SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE,
SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {
fprintf(stderr, "fatal error: could not open input port.\n");
exit(1);
}
/* open 16 output ports for the MIDI channels */
for (i=0; i<16; i++){
sprintf( txt, "MIDI Channel %d", i );
if ((oportid[i] = snd_seq_create_simple_port
(seq_handle, txt,
SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ,
SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {
fprintf(stderr, "fatal error: could not open output port.\n");
exit(1);
}
}
npfd = snd_seq_poll_descriptors_count(seq_handle, POLLIN);
pfd = (struct pollfd *)alloca(npfd * sizeof(struct pollfd));
snd_seq_poll_descriptors(seq_handle, pfd, npfd, POLLIN);
while (1) /* main loop */
if (poll(pfd, npfd, 1000000) > 0){
do {
snd_seq_event_input(seq_handle, &ev);
snd_seq_ev_set_source( ev, oportid[ev->data.control.channel] );
snd_seq_ev_set_subs( ev );
snd_seq_ev_set_direct( ev );
snd_seq_event_output_direct( seq_handle, ev );
snd_seq_free_event(ev);
} while (snd_seq_event_input_pending(seq_handle, 0) > 0);
}
return 0;
}
______________________________________________________________________
9.3. Example 3
Below is an example of writing data to the OSS /dev/midi interface by
Craig Stuart Sapp.
More examples can be found at Craig's site listed in the Links
section.
______________________________________________________________________
//
// Programmer: Craig Stuart Sapp [craig@ccrma.stanford.edu]
// Creation Date: Mon Dec 21 18:00:42 PST 1998
// Last Modified: Mon Dec 21 18:00:42 PST 1998
// Filename: ...linuxmidi/output/method1.c
// Syntax: C
// $Smake: gcc -O -o devmidiout devmidiout.c && strip devmidiout
//
#include <linux/soundcard.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
int main(void) {
char* device = "/dev/midi" ;
unsigned char data[3] = {0x90, 60, 127};
// step 1: open the OSS device for writing
int fd = open(device, O_WRONLY, 0);
if (fd < 0) {
printf("Error: cannot open %s\n", device);
exit(1);
}
// step 2: write the MIDI information to the OSS device
write(fd, data, sizeof(data));
// step 3: (optional) close the OSS device
close(fd);
return 0;
}
______________________________________________________________________
10. HOWTO Use MIDI Sequencers With Softsynths.
Frank Barknecht <barknech@ph-cip.uni-koeln.de>
<http://linux-sound.org/quick-toots/4-sequencers_and_softsynths/quick-
toot-midisynth_howto.html>
This HOWTO describes the needed setup to control a MIDI capable
software synthesizer from a MIDI sequencer through a virtual MIDI
connection under ALSA 0.9. This document can be freely translated and
distributed. It's released under the GNU Free Documentation License.
10.1. Introduction
Software synthesizers like Csound, PD, jMax or Spiral Synth Modular
offer nearly endless freedom to create known or unknown, common or
unusual sound experiences. They can also replace pricy hardware synths
or the inexpensive, often bad-sounding MIDI synths on some soundcards,
if these are supported under Linux at all. On the other hand,
composing inside those softsynths can be a tedious task: in Csound for
example one has to write endless rows of numbers in a spreadsheet-like
manner - not a comfortable way to make music.
MIDI sequencer applications are more suitable for this task. They
provide an interface to insert notes and control data in convenient
ways: as notes in a real score, as marks in a piano roll or as a list
of MIDI events, if you prefer this view. Another kind of MIDI
sequencers offer a tracker-like way of entering notes, like many
people are used to from the good old days when that was the state of
art in the Scene. Last but not least, some MIDI sequencers allow you
to record your own playing on a keyboard or on another physical
device, which is for many users the most natural way of writing music.
But MIDI sequencers like to output their notes to MIDI devices that
normally route their events to the outside world, i.e., to hardware
synths and samplers. With virtual MIDI devices one can keep the MIDI
data inside the computer and let it control other software running on
the same machine. This HOWTO describes all that is necessary to
achieve this goal.
10.2. Device Setup
In our setup we use the ALSA library and driver modules, as this is
(or should be) the standard way of doing serious audio and MIDI on
Linux. The tutorial assumes that we are running the 0.9.0 branch of
ALSA, but the virtual MIDI module was also present in ALSA 0.5.x so
most of the following should apply for this as well. In the OSS/Free
(the sound modules found in kernels previous to the 2.5.x track) and
OSS/Linux sound architectures the v_midi module can be used, but this
is beyond the scope of this document.
To use ALSA's virtual MIDI card the snd-card-virmidi module must be
present. In the most recent versions of ALSA (and in the 2.5.x
development kernel) that module lost its '-card' middle-fix and was
renamed to snd-virmidi. Make sure that you did build this module, it
might be missing if you configured ALSA to build only the modules for
your actual card(s).
The virmidi module has to be loaded to make the virtual MIDI ports
available. You can test-load it by hand with
______________________________________________________________________
$ modprobe snd-virmidi snd_index=1
______________________________________________________________________
where snd_index is set appropriately to the first free card index (=1
if you have only one card that already has index 0), but it is more
convenient to adapt your modules configuration to have it sitting
around already when you need it. For that we need to extend the ALSA
section in /etc/modules.conf (or in another location, depending on
your distribution) with the following:
______________________________________________________________________
# Configure support for OSS /dev/sequencer and
# /dev/music (aka /dev/sequencer2)
# (Takashi Iwai advises that it is unnecessary
# to alias these services beyond the first card, i.e., card 0)
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-8 snd-seq-oss
# Configure card 1 (second card) as a virtual MIDI card
alias sound-slot-1 snd-card-1
alias snd-card-1 snd-virmidi
______________________________________________________________________
Now you have configured a virtual MIDI card as the second card with
index 1, assuming you have one real soundcard (which would be very
useful). If you have a second real card like I do, change the configu
ration above to read:
______________________________________________________________________
# Configure card 2 (third card) as a virtual MIDI card
alias sound-slot-2 snd-card-2
alias snd-card-2 snd-virmidi
______________________________________________________________________
If you have even more cards, well, you should know the deal by now...
It might be necessary to restart the ALSA sound system, after which
the virtual MIDI card should be seen in /proc/asound/cards:
______________________________________________________________________
$ cat /proc/asound/cards
0 [card0 ]: ICE1712 - M Audio Audiophile 24/96
M Audio Audiophile 24/96 at 0xb800, irq 5
1 [card1 ]: EMU10K1 - Sound Blaster Live!
Sound Blaster Live! at 0xc800, irq 11
2 [card2 ]: VirMIDI - VirMIDI
Virtual MIDI Card 1
______________________________________________________________________
In this example of my own machine I have the VirMIDI card as third
card, index 2. This setup results in the following raw MIDI devices,
found in /proc/asound/devices [showing only the MIDI devices]:
______________________________________________________________________
$ cat /proc/asound/devices
8: [0- 0]: raw MIDI
41: [1- 1]: raw MIDI
42: [1- 2]: raw MIDI
75: [2- 3]: raw MIDI
74: [2- 2]: raw MIDI
73: [2- 1]: raw MIDI
72: [2- 0]: raw MIDI
______________________________________________________________________
The devices starting with '2-' are my virtual MIDI devices. Yours
would start with '1-' if you only had one physical card in your
system.
You can get a nicer listing with ALSA's own aconnect utility, which we
will need anyway. Called with option -o (or -lo) it will show the MIDI
devices capable of MIDI output, while a call with -i shows those with
MIDI input capabilities:
______________________________________________________________________
$ aconnect -o
[...]
client 80: 'Virtual Raw MIDI 2-0' [type=kernel]
0 'VirMIDI 2-0 '
client 81: 'Virtual Raw MIDI 2-1' [type=kernel]
0 'VirMIDI 2-1 '
client 82: 'Virtual Raw MIDI 2-2' [type=kernel]
0 'VirMIDI 2-2 '
client 83: 'Virtual Raw MIDI 2-3' [type=kernel]
0 'VirMIDI 2-3 '
$ aconnect -i
[...]
client 80: 'Virtual Raw MIDI 2-0' [type=kernel]
0 'VirMIDI 2-0 '
client 81: 'Virtual Raw MIDI 2-1' [type=kernel]
0 'VirMIDI 2-1 '
client 82: 'Virtual Raw MIDI 2-2' [type=kernel]
0 'VirMIDI 2-2 '
client 83: 'Virtual Raw MIDI 2-3' [type=kernel]
0 'VirMIDI 2-3 '
______________________________________________________________________
The devices shown correspond to ALSA's own OSS-compatible raw MIDI
devices in the /proc/asound/dev directory tree. For example
/proc/asound/dev/midiC2D0 is the first MIDI device of our virtual MIDI
card at index 2, called Virtual Raw MIDI 2-0 by aconnect. In Debian
those devices are available in /dev/snd/ as well, and they also are
internally linked with the old OSS device locations: /dev/midiXX. To
make sure that I can get the ALSA raw MIDI ports from /dev/midiXX I
symlinked them with
______________________________________________________________________
$ ln -s /dev/snd/midiC2D0 /dev/midi20
$ ln -s /dev/snd/midiC2D1 /dev/midi21
[...]
______________________________________________________________________
but this should not be necessary, so don't do this at home, kids!
Now that we have created and configured a VirtualMIDI card we can use
it in our applications just like any other MIDI devices. Just insert
the needed device, be it an OSS-compatible /dev/midi20 or an ALSA MIDI
port like 80:0, at the correct configuration point of your favourite
sequencer and synthesizer application.
10.3. Routing MIDI Events
10.3.1. aconnect
Without further arrangements we will not be able to send the MIDI
events from our sequencer to a softsynth. For that, we first need to
connect two ports with (you guessed it) the aconnect utility. This
tool connects two or more ports. Its -i and -o output above has
already shown us the available ports, and with a simple syntax these
can now be connected in a one-way fashion:
______________________________________________________________________
$ aconnect [sender port] [receiver port]
$ aconnect 80:0 81:0
______________________________________________________________________
This routes all MIDI data sent to port 80:0 over to port 80:1. In our
setup this means that every event coming in at /dev/midi20 gets sent
to /dev/midi21, where it can be read ('received') by another
application.
If you had configured the VirMIDI card as your second card (with card
index 1) you should have these ports:
______________________________________________________________________
$ aconnect -lo
client 72: 'Virtual Raw MIDI 1-0' [type=kernel]
0 'VirMIDI 1-0 '
client 73: 'Virtual Raw MIDI 1-1' [type=kernel]
0 'VirMIDI 1-1 '
client 74: 'Virtual Raw MIDI 1-2' [type=kernel]
0 'VirMIDI 1-2 '
client 75: 'Virtual Raw MIDI 1-3' [type=kernel]
0 'VirMIDI 1-3
______________________________________________________________________
Here you can connect for example port 72:0 (/dev/midi10) to port 73:0
(/dev/midi11) with:
______________________________________________________________________
$ aconnect 72:0 73:0
______________________________________________________________________
aconnect can show us what was created with its -lo and -li options:
______________________________________________________________________
$ aconnect -lo
client 72: 'Virtual Raw MIDI 1-0' [type=kernel]
0 'VirMIDI 1-0 '
Connecting To: 73:0
client 73: 'Virtual Raw MIDI 1-1' [type=kernel]
0 'VirMIDI 1-1 '
Connected From: 72:0
client 74: 'Virtual Raw MIDI 1-2' [type=kernel]
0 'VirMIDI 1-2 '
client 75: 'Virtual Raw MIDI 1-3' [type=kernel]
0 'VirMIDI 1-3
______________________________________________________________________
You see that 'Virtual Raw MIDI 1-0' now is connected to 'Virtual Raw
MIDI 1-1'. Now, depending on your applications, you can read MIDI data
that was sent to 'Virtual Raw MIDI 1-0' from 'Virtual Raw MIDI 1-1',
or in OSS-device speak: What was sent to /dev/midi10 gets routed to
/dev/midi11 and can be read from there.
You can also connect more than one port to a port. If you call
aconnect twice like this:
______________________________________________________________________
$ aconnect 72:0 73:0
$ aconnect 72:0 74:0
______________________________________________________________________
you can receive the same data send to /dev/midi10 at /dev/midi11 and
at /dev/midi12 as well. And of course you can really hammer your
machine if you create more VirMIDI cards and wildly connect these.
There's no stopping us now...
To disconnect all ports use
______________________________________________________________________
$ aconnect -x
______________________________________________________________________
or disconnect only one connection with:
______________________________________________________________________
$ aconnect -d 72:0 74:0
______________________________________________________________________
10.4. Graphical MIDI Patch Bays
Bob Ham's ALSA MIDI Patch Bay is a very useful graphic frontend to
ALSA's MIDI connection setup. Usage is very simple and intuitive: On
the left are the MIDI ports that are capable of sending MIDI events,
while on the right you see the ports with receiving capability. If you
click on a left-side port it gets selected for a new connection to the
port on the right that you click next. Clicking on a right-side port
will disconnect the port if it was connected. A clean and easy tool
that has the potential to redundantize this HOWTO. ;)
10.4.1. aseqview
Another useful tool for routing MIDI events is aseqview by ALSA
developer Takashi Iwai. You can download it at Iwai-sama's homepage
http//members.tripod.de/iwai/alsa.html, but it is also included in
many distributions. This graphic utility was designed to view and
change MIDI events as they pass through your computer, but it also has
the capability to route events to different MIDI ports like aconnect
does. This comes in handy when you have to deal with applications that
use the OSS sequencer device, which aconnect is sometimes unable to
reach. If you start aseqview without any options you get a nice GUI
and a new MIDI port. The default is port 128:0, and it looks like
this:
______________________________________________________________________
client 128: 'MIDI Viewer' [type=user]
0 'Viewer Port 0 '
______________________________________________________________________
With this port all the aconnect tricks that we have seen by now are
possible. But if you just need to connect the aseqview port to another
port, aseqview can do this by itself with the -d option :
______________________________________________________________________
$ aseqview -d 73:0 &
______________________________________________________________________
This connects port 128:0 (if that was available) to port 73:0 right
from the start of aseqview.
There are some more graphical aconnect tools with very similar
functionality. Maarten de Boer used most af the original aconnect
source code to write a graphical frontend called "aconnectgui" with
the FLTK toolkit. It is available at
<http://www.iua.upf.es/~mdeboer/>. His software has the best looks,
in my opinion.
Personally I use kaconnect, maybe because it has the shortest name,
that is the fastest to type. kaconnect was developed by Suse's own Dr.
Matthias Nagorni as a part of his series of tools and softsynths for
ALSA, the kalsatools. Don't let the "k" in the name fool you, the
software does not require KDE, it uses the pure QT GUI libraries.
kaconnect and more is available at
<http://www.suse.de/~mana/kalsatools.html>.
10.5. Applications
In this last section I will show some examples, how to use the virtual
MIDI connections in various applications. I will assume a VirMIDI card
as a third card in the system, using ALSA MIDI ports 80:0 to 83:0 that
correspond to the raw OSS MIDI devices /dev/midi20 to /dev/midi23 and
to the ALSA raw MIDI devices /dev/snd/midiC2D0 to /dev/snd/midiC2D3.
Of these, the first two have been 'aconnected' with
______________________________________________________________________
$ aconnect 80:0 81:0
______________________________________________________________________
As shown, this means, that all MIDI data sent to /dev/midi20 (or port
80:0 or /dev/snd/midiC2D0) can now be read at /dev/midi21 (or port
80:1 or /dev/snd/midiC2D1)
10.6. Sequencers
10.6.1. MusE
MusE is a full-featured MIDI sequencer written by Werner Schweer,
available at http://muse.seh.de. We will need to configure the the
virtual MIDI port as an output port in the section 'Config->MIDI
Ports'. In MusE, the ports are named by their ALSA names 'VirMIDI X-
X':
Now make sure that the right port is selected as the output port for
the channel on which you want the software synthesizer to listen to
and play the MIDI events:
For some reason I could not use 'VirMIDI 2-0' as output device in MusE
0.4.9. That is the expected device when I wanted to receive on
'VirMIDI 2-1' but I had to use it the other way around. I don't know
why, I'm probably stupid, and you might have to experiment a bit. One
could also use the midi02 or midi2 devices.
10.6.2. ttrk
Billy Biggs's ttrk is a simple, quick and tight MIDI sequencer with a
tracker interface. It can output its MIDI data to any MIDI port
configured in the file $HOME/.ttrkrc.
Put this line there to have ttrk write to /dev/snd/midiC2D0: and
you're good to go...
10.6.3. Shaketracker
Juan Linietsky's Shaketracker revives the MIDI tracker interface like
ttrk, but it has a more complete translation of the classic tracker
effects to MIDI data. Unfortunatly it uses the OSS sequencer device
(/dev/sequencer) for its MIDI output, not the raw MIDI devices, and I
could not get it to work with aconnect. But there is a workaround that
involves aseqview. If we start aseqview before Shaketracker, the
tracker will recognize and use the aseqview port. One just has to
select it in the 'User Devices' section of Shaketracker, where it
shows up by its ALSA name 'Viewer Port 0':
It is convenient to give this User Device a good name instead of 'Null
Output'.
If we start aseqview without options we would need to aconnect the
aseqview port with the softsynth port, but as shown previously we
could also start aseqview directly with a destination port. Don't
forget to use the new User Device in every track that should go to the
softsynth. I always run Shaketracker with a little shell script that
starts aseqview, waits for the creation of ports, and then starts
Shaketracker:
______________________________________________________________________
#!/bin/sh
aseqview -d 81:0 &
# sleep 2 seconds to let aseqview do its work:
sleep 2
shaketracker
______________________________________________________________________
10.7. Software Synthesizer
10.7.1. Pure Data
Miller Puckette is the genius behind the open-source software
synthesis and multimedia development environment Pure Data (PD), which
evolved out of MAX and in turn was the basis for the MAX-extension
MSP. PD can use raw MIDI devices to read MIDI events that are
specified with the option '-midiindev <devnumber>' but it has an
irritating way of specifying which device to use. The formula is as
follows: To use /dev/midi0, start PD with 'midiindev 1', to use
/dev/midi1 start it with '-midiindev 2' and so on. Got it? You must
specify the real device number plus 1 here. Another example: For
/dev/midi21 start PD with '-midiindev 22'
PD has a help patch 'Test audio and MIDI', that is invaluable in
locating the right MIDI device:
10.7.2. Csound
Csound is the grandmother of most of todays software synthesizers, and
it has learned MIDI as well. Running 'csound --help' shows where one
has to configure the MIDI input device:
-M dnam or --midieventdev=dnam ........ Read MIDI realtime events from
device
So in our example we need to start Csound as
______________________________________________________________________
$ csound -M /dev/midi22 -o devaudio midi.csd
______________________________________________________________________
10.7.3. Conclusion
By now you should know how to use a software synthesizer to
orchestrate music composed in and played by a MIDI sequencer. Of
course, tools like aconnect and aseqview don't need to be used with a
MIDI software sequencer. You could also redirect events that come into
your machine from an external sequencer or from an external MIDI
keyboard directly to the software synth without the MIDI sequencer
step. Just 'aconnect' the external MIDI device to your softsynth or to
the on-board synth of your soundcard. Or go the other way around: PD,
Csound or environments like KeyKit allow you to create MIDI events in
algorithmic ways that are nearly impossible with classic Cubase-like
MIDI sequencers. With aconnect you can route these events to any MIDI
capable sound module you have.
10.8. Acknowledgments
The author would like to thank Takashi Iwai for his technical
assistance in preparing this article and for his invaluable advice
regarding the Japanese language. Thanks, Takashi !
11. Useful Links.
Below is a list of links to sites and resources covering MIDI and
Linux.
<http://www.linux-sound.org/> Sound & MIDI Software For Linux. A huge
resource of MIDI and Audio related information.
<http://www.linuxdj.com/audio/lad/> Linux Audio Developers mailing
list. For developer related discussion.
<http://www.linuxdj.com/audio/quality> The Linux Audio Quality HOWTO.
A good section on MIDI cards, essential reading for building a Linux
studio.
<http://www.alsa-project.org/> Alsa Project - Audio/MIDI Driver
<http://www.4front-tech.com/> OSS - Audio/MIDI Driver
<http://www.gardena.net/benno/linux/audio/> Low Latancy patches
<http://ccrma-www.stanford.edu/~craig/articles/linuxmidi/>
Introduction to MIDI programming in Linux. Craig Stuart Sapp covers
writing basic MIDI utilities in C/C++ for the OSS driver.
<http://www.suse.de/~mana> Excellent collection of ALSA 0.9 MIDI and
PCM example C programs by Dr. Matthias Nagorni.
12. Feedback.
As ever, a HOWTO is a work in progress. You are encouraged to give
feedback on new applications and other interesting developments with
MIDI under Linux.
MIDI cards are, by their wide variety, sometimes difficult to
configure as they have various levels of driver support and
configuration options. Your best source of reference for problems are
ALSA's and OSS's websites, newsgroups, and if you get stuck please try
searching the Linux Audio mailing lists.
