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Dynamic and static MIDI bridging between JACK MIDI and ALSA sequencer graphs
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LADI/a2jmidid
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= Overview = Main goal of this project main is to ease usage of legacy, not JACK-ified apps, in a JACK MIDI enabled system. There are two ways to use legacy ALSA sequencer applications in JACK MIDI system. The first approach is to use automatic bridging. For every ALSA sequencer port you get one JACK MIDI port. If ALSA sequencer port is both input and output one, you get two JACK MIDI ports, one input and output. The second approach is to static bridges. You start application that creates one ALSA sequencer port and one JACK MIDI port. Such bridge is unidirectional. First approach works almost always except when legacy ALSA sequencer application does not create ports and/or wants existing port to exist so it can capture from or playback to it. Such programs are using the feature of ALSA sequencer framework that allows sending and receiving MIDI events to/from port, without creating connection to it. = a2jmidid = a2jmidid is daemon that implements automatic bridging. For every ALSA sequencer port you get one jack midi port. If ALSA sequencer port is both input and output one, you get two JACK MIDI ports, one input and output. a2jmidid has two modes of operation, running bridge manually and background D-Bus service. To start a2jmidid in manual mode, just run it (and don't supply the special "undocumented" dbus parameter). a2jmidid will start bridging, and you will get output on stdout and stderr. You can stop the bridge using ctrl-c. Usually you want to bridge software ports and not bridge hardware ports (they are handled by JACK itself). In case you want to force a2jmidid to bridge hardware ports, you can use the export-hw option: a2jmidid -e or a2jmidid --export-hw In D-Bus service mode, a2jmidid works in background. When service access is requested by some application (like a2j_control), dbus session bus daemon activates the object by executing the service executable. The object has methods for starting and stopping the bridging. You can use a2j_control to do this: a2j_control start a2j_control stop You can deactivate (that may cause later reactivation) the service like this: a2j_control exit You can query the bridge status using this command: a2j_control status There also methods (and corresponding a2j_control commands) that can be used to query mapping information. a2jmidid implementation is based on jack-alsamidi-0.5 that is [almost] same as jackd ALSA "seq" MIDI backend), both created by Dmitry Baikov. = a2jmidi_bridge = a2jmidi_bridge is static bridge that creates one ALSA sequencer playback port and one JACK MIDI capture port. MIDI events sent to ALSA sequencer playback port can be read from the JACK MIDI capture port. a2jmidi_bridge has optional argument that allows overriding name used for JACK and ALSA client: a2jmidi_bridge "my precious bridge" a2jmidi_bridge implementation is based on alsaseq2jackmidi by Sean Bolton. = j2amidi_bridge = j2amidi_bridge is static bridge that creates one JACK MIDI playback port and one ALSA sequencer capture port. MIDI events sent to JACK MIDI playback port can be read from the ALSA sequencer capture port. j2amidi_bridge has optional argument that allows overriding name used for JACK and ALSA client: j2amidi_bridge "my precious bridge" j2amidi_bridge implementation is based on jackmidi2alsaseq by Lars Luthman. = Contact info = If someone wants to contribute please, contact me (Nedko Arnaudov), or send patches, or request inclusion (Gna! a2jmidid project). Packagers are more than welcome too.
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Dynamic and static MIDI bridging between JACK MIDI and ALSA sequencer graphs