| SUSE LINUX – User Guide Chapter 15. Sound in Linux / 15.9. ALSA and MIDI | ||||
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 | 15.8. Compressing Audio Data | 15.10. MIDI Playback without a WaveTable Card |  | |
| SUSE LINUX – User Guide Chapter 15. Sound in Linux / 15.9. ALSA and MIDI | ||||
|---|---|---|---|---|
| 15.8. Compressing Audio Data | 15.10. MIDI Playback without a WaveTable Card | | |
Apart from the possibility to play PCM data, many sound cards also offer MIDI functionality. The ALSA MIDI sequencer implements an efficient architecture for routing MIDI data. You need the packages pmidi, aseqview, vkeybd, awesfx, snd_sf2, and kalsatools.
Many sound cards have an external MIDI port for connecting MIDI devices, such as synthesizers, keyboards, and sound modules. If the MIDI port of the card is supported by ALSA, use a sequencer application, such as jazz, to record and play MIDI files. An overview of the MIDI devices provided by your card is available in the KDE Control Center under ++. Here, also determine the devices to use for playing MIDI files. On the command line, list the available MIDI devices and their internal ALSA port numbers with the command pmidi -l. For a Soundblaster Live! card, the listing would appear as in Example 15.1. “MIDI Devices of a Soundblaster Live! Card”.
Example 15.1. MIDI Devices of a Soundblaster Live! Card
Port Client name Port name 72:0 External MIDI 0 MIDI 0-0 73:0 Emu10k1 WaveTable Emu10k1 Port 0 73:1 Emu10k1 WaveTable Emu10k1 Port 1 73:2 Emu10k1 WaveTable Emu10k1 Port 2 73:3 Emu10k1 WaveTable Emu10k1 Port 3
The first column lists the internal port numbers by which the device is addressed by the ALSA driver. The other columns show the designation and port name of the device. Apart from the external MIDI port, several WaveTable ports are listed. Use a command like pmidi -p 73:0 mysong.mid to play a MIDI file over one of the listed ports.
![[Important]](admon/important.png) | Important |
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If a MIDI player is interrupted during playback, a continuous sound may persist. If this happens, run the all_notes_off script or restart ALSA as root with rcalsasound restart. | |
Many sound cards (like Soundblaster AWE and Live!) have an internal WaveTable synthesizer that converts MIDI events into audible sounds. These MIDI events can be sent to the WaveTable synthesizer by an external MIDI keyboard or by a program, such as a MIDI player or sequencer. For Soundblaster AWE and Live! cards, the WaveTable synthesizer must be initialized with a sound font before any sound can be heard.
The package awesfx contains the sfxload command for loading sound fonts in Soundblaster AWE and Live! cards. Suitable sound font files are available on the driver CD of your sound card. The start-up script of ALSA can automatically load the sound fonts required for the WaveTable synthesis, provided the respective files were installed from the Creative driver CD using YaST. Currently, the script only works for one sound card. However, ALSA can easily manage up to eight sound cards.
Sound fonts can be loaded with a command like sfxload -D <n> /usr/share/sfbank/creative/8MBGMSFX.SF2. n stands for the number of the sound card (0, 1, etc.). This may not be the number under which the sound card was configured. This number is instead determined by the order in which the individual sound drivers are loaded.
You can also load one of the sound fonts installed in /usr/share/sounds/sf2. The sound font Vintage_Dreams_Waves_v2.sf2 by Ian Wilson contains 128 analog synthesizer sounds and eight drum sets. It is suitable for SB AWE as well as for SB Live! cards. The ROM sound font gu11-rom.sf2 by Samuel Collins is only suitable for SB AWE cards. It provides an extended general MIDI bank for these cards. Review the copyright files and the documentation in /usr/share/doc/packages/snd_sf2. More sound fonts are available at URLs such as http://www.hammersound.net.
If you do not have an external MIDI keyboard connected to your sound card, use the virtual keyboard vkeybd. For this purpose, the internal port numbers listed with pmidi -l as described above are important. To start the program from the command line, enter vkeybd --addr 73:0 &. The port address must be adapted to your system. Specify the first WaveTable port from the list. If an external sound generator is connected, alternatively specify the port number of the external MIDI port.
vkeybd supports a number of additional options. For example, enter vkeybd --addr 73:0 --octave 5 & to increase the number of displayed octaves to five. An overview of the command line options can be accessed with vkeybd --help or in vkeybd.
The instrument designation in the preset list can be configured by specifying a preset file with the --preset option. Extract the instrument names of a sound font file with the command sftovkb. Change to the respective directory with cd /usr/share/sounds/sf2 and enter the command sftovkb Vintage_Dreams_Waves_v2.sf2 >~/vintage.vkb to save the names in your home directory in vintage.vkb. The vkeybd interface can be configured with the menu.
The mapping of the keys to the sent MIDI notes is saved in the file ~/.vkeybdrc. Additional specifications can be made in this file. To implement your own modifications, retrieve the designations of keyboard events with the xev program.
ALSA provides an efficient infrastructure for the connection of several MIDI ports. Sound cards and MIDI programs (provided these support the ALSA sequencer structure) have one or several MIDI ports for communicating with each other. These ports can be connected with the KDE program kaconnect or the command aconnect. On start-up, kaconnect shows the readable and writable MIDI ports available on your system and the connection status. To test the procedure, start two MIDI programs with the commands vkeybd and aseqview. For the connection between MIDI ports, specify the port address of the program after the program name. For example, assign port number 128:0 to the first program and 129:0 to the second. The ports of the programs are also displayed by kaconnect.
As vkeybd was executed without the --addr parameter, the connection between the program port and the WaveTable port (or the external MIDI) port can now be established manually. To do this, select the respective ports and click . To use the command-line tool aconnect, enter aconnect 128:0 73:0 (or the respective ports) to establish a unidirectional connection between the sender port 128:0 and the receiver port 73:0.
You can now establish a connection between the MIDI port of the keyboard and the MIDI port of the ALSA sequencer viewer. If you modify keyboard settings, such as the panning or the pitch wheel (which must first be activated under ), these changes are promptly reflected in aseqview.
List the ports available for sending and receiving as well as their connection status with aconnect -il or aconnect -ol. Terminate connections established with aconnect with the option -d, for example, aconnect -d 128:0 129:0. To terminate all connections, enter aconnect -x. Get information about other options with man aconnect.
![[Tip]](admon/tip.png) | Tip |
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aseqnet can be used to establish MIDI connections over a network. | |
The program QMidiRoute enables flexible MIDI routing. The MIDI events as received at the writable MIDI port are presented as one or several maps, from which they can be selected and transformed into other events. To mention just one practical application of this technique, you could split a keyboard into several regions, each sending on a different MIDI channel. QMidiRoute also has a window listing all MIDI events received on the input port.
