--- name: "MIDI::ALSA" section: "3pm" platform: "linux" package: "libmidi-alsa-perl" version: "1.22-2+b1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/MIDI::ALSA" --- # MIDI::ALSA(3pm) the ALSA library, plus some interface functions ## NAME MIDI::ALSA - the ALSA library, plus some interface functions ## SYNOPSIS ``` use MIDI::ALSA(':CONSTS'); MIDI::ALSA::client( 'Perl MIDI::ALSA client', 1, 1, 0 ); MIDI::ALSA::connectfrom( 0, 14, 0 ); # input port is lower (0) MIDI::ALSA::connectto( 1, 20, 0 ); # output port is higher (1) while (1) { my @alsaevent = MIDI::ALSA::input(); if ($alsaevent[0] == SND_SEQ_EVENT_PORT_UNSUBSCRIBED()) { last; } if ($alsaevent[0] == SND_SEQ_EVENT_NOTEON()) { my $channel = $alsaevent[7][0]; my $pitch = $alsaevent[7][1]; my $velocity = $alsaevent[7][2]; } elsif ($alsaevent[0] == SND_SEQ_EVENT_CONTROLLER()) { my $channel = $alsaevent[7][0]; my $controller = $alsaevent[7][4]; my $value = $alsaevent[7][5]; } MIDI::ALSA::output( @alsaevent ); } ``` ## DESCRIPTION This module offers a Perl interface to the *ALSA* library. It is a call-compatible translation into Perl of the Lua module *midialsa* http://www.pjb.com.au/comp/lua/midialsa.html which is in turn based on the Python modules *alsaseq.py* and *alsamidi.py* by Patricio Paez. It also offers some functions to translate events from and to the event format used in Sean Burke's MIDI-Perl module. Nothing is exported by default, but all the functions and constants can be exported, e.g.:\ use MIDI::ALSA(client, connectfrom, connectto, id, input, output);\ use MIDI::ALSA(':CONSTS'); As from version 1.15, note durations are in seconds rather than milliseconds, for consistency with the timestamps. This introduces a backward incompatibility which only affects you if are putting together your own alsaevents without using the **noteevent()** function. In the worst case you have to detect versions: ``` if ($MIDI::ALSA::VERSION < 1.145) { $alsevent[7][4] *= 1000; } ``` ## FUNCTIONS Functions based on those in *alsaseq.py*: **client()**, **connectfrom()**, **connectto()**, **disconnectfrom()**, **disconnectto()**, **fd()**, **id()**, **input()**, **inputpending()**, **output()**, **start()**, **status()**, **stop()**, **syncoutput()** Functions based on those in *alsamidi.py*: **noteevent()**, **noteonevent()**, **noteoffevent()**, **pgmchangeevent()**, **pitchbendevent()**, **controllerevent()**, **chanpress()**, **sysex()** Functions to interface with *MIDI-Perl*: **alsa2scoreevent()**, **scoreevent2alsa()** Functions to get the current ALSA status: **listclients()**, **listnumports()**, **listconnectedto()**, **listconnectedfrom()**, **parse\_address()** - client($name, $ninputports, $noutputports, $createqueue) Create an ALSA sequencer client with zero or more input or output ports, and optionally a timing queue. ninputports and noutputports are created if the quantity requested is between 1 and 64 for each. If *createqueue* = true, it creates a queue for stamping the arrival time of incoming events and scheduling future start times of outgoing events. For full ALSA functionality, the *$name* should contain only letters, digits, underscores or spaces, and should contain at least one letter. Unlike in the *alsaseq.py* Python module, it returns success or failure. - connectfrom( $inputport, $src\_client, $src\_port ) Connect from *src\_client:src\_port* to *inputport*. Each input port can connect from more than one client. The *input*() function will receive events from any intput port and any of the clients connected to each of them. Events from each client can be distinguised by their source field. Unlike in the *alsaseq.py* Python module, it returns success or failure. Since version 1.11, and unlike in the *alsaseq.py* Python module, if `$src_client` contains a letter or `$src_port` is undefined, then *parse\_address($src\_client)* automatically gets invoked. This allows you to refer to the clients by name, for example connectfrom($inputport,'Virtual:1') will connect from port 1 of the 'Virtual Raw MIDI' client. - connectto( $outputport, $dest\_client, $dest\_port ) Connect *outputport* to *dest\_client:dest\_port*. Each output port can be Connected to more than one client. Events sent to an output port using the *output*() function will be sent to all clients that are connected to it using this function. Unlike in the *alsaseq.py* Python module, it returns success or failure. Since version 1.11, and unlike in the *alsaseq.py* Python module, if `$dest_client` contains a letter or `$dest_port` is undefined, then *parse\_address($dest\_client)* automatically gets invoked. This allows you to refer to the clients by name, for example connectto($outputport,'Virtual:1') will connect to port 1 of the 'Virtual Raw MIDI' client. - disconnectfrom( $inputport, $src\_client, $src\_port ) Disconnect the connection from the remote *src\_client:src\_port* to my *inputport*. Returns success or failure. Since version 1.11, and unlike in the *alsaseq.py* Python module, if `$dest_client` contains a letter or `$dest_port` is undefined, then *parse\_address($src\_client)* automatically gets invoked. This allows you to refer to the clients by name, for example disconnectfrom($inputport,'Virtual:1') will disconnect from port 1 of the 'Virtual Raw MIDI' client. - disconnectto( $outputport, $dest\_client, $dest\_port ) Disconnect the connection from my *outputport* to the remote *dest\_client:dest\_port*. Returns success or failure. Since version 1.11, and unlike in the *alsaseq.py* Python module, if `$dest_client` contains a letter or `$dest_port` is undefined, then *parse\_address($dest\_client)* automatically gets invoked. This allows you to refer to the clients by name, for example disconnectto($outputport,'Virtual:1') will disconnect to port 1 of the 'Virtual Raw MIDI' client. - **fd()** Return fileno of sequencer. This piece of code, contributed by Daren Schwenke, uses the *AnyEvent* module to build an application which waits both for ALSA events, and for user-input: ``` my $alsa_midi = AnyEvent->io ( fh => MIDI::ALSA::fd(), poll => "r", cb => sub { my @alsaevent = MIDI::ALSA::input(); print "Alsa event: " . Dumper(\@alsaevent); } ); ``` - **id()** Return the client number, or 0 if the client is not yet created. - **input()** Wait for an ALSA event in any of the input ports and return it. ALSA events are returned as an array with 8 elements: ``` ($type, $flags, $tag, $queue, $time, \@source, \@destination, \@data) ``` Unlike in the *alsaseq.py* Python module, the time element is in floating-point seconds. The last three elements are also arrays: ``` @source = ( $src_client, $src_port ) @destination = ( $dest_client, $dest_port ) @data = ( varies depending on type ) ``` The *source* and *destination* arrays may be useful within an application for handling events differently according to their source or destination. The event-type constants, beginning with SND\_SEQ\_, are available as module subroutines with empty prototypes, not as strings, and must therefore be used without any dollar-sign e.g.: ``` if ($event[0] == MIDI::ALSA::SND_SEQ_EVENT_PORT_UNSUBSCRIBED) { ... ``` The data array is mostly as documented in http://alsa-project.org/alsa-doc/alsa-lib/seq.html. For NOTE events, the elements are ( `$channel`, `$pitch`, `$velocity`, unused, `$duration` ); where since version 1.15 the *duration* is in floating-point seconds (unlike in the *alsaseq.py* Python module where it is in milliseconds). For SYSEX events, the data array contains just one element: the byte-string, including any F0 and F7 bytes. For most other events, the elements are ($channel, unused,unused,unused, `$param`, `$value`) The *channel* element is always 0..15 In the SND\_SEQ\_EVENT\_PITCHBEND event the *value* element is from -8192..+8191 (not 0..16383) If a connection terminates, then **input()** returns, and the next event will be of type SND\_SEQ\_EVENT\_PORT\_UNSUBSCRIBED Note that if the event is of type SND\_SEQ\_EVENT\_PORT\_SUBSCRIBED or SND\_SEQ\_EVENT\_PORT\_UNSUBSCRIBED, then that message has come from the System, and its *dest\_port* tells you which of your ports is involved. But its *src\_client* and *src\_port* do not tell you which other client disconnected; you'll need to use ***listconnectedfrom()*** or ***listconnectedto()*** to see what's happened. - **inputpending()** Return the number of bytes available in input buffer. Use before **input()** to wait till an event is ready to be read. - output($type,$flags,$tag,$queue,$time,\\@source,\\@destination,\\@data) Send an ALSA-event from an output port. The format of the event is as discussed in **input()** above. The event will be output immediately either if no queue was created in the client or if the *queue* parameter is set to SND\_SEQ\_QUEUE\_DIRECT, and otherwise it will be queued and scheduled. The *@source* is an array with two elements: ($src\_client, `$src_port`), specifying the local output-port from which the event will be sent. If only one output-port exists, all events are sent from it. If two or more exist, the *$src\_port* determines which to use. The smallest available port-number (as created by *client*()) will be used if *$src\_port* is less than it, and the largest available will be used if *$src\_port* is greater than it. The *@destination* is an array with two elements: ($dest\_client, `$dest_port`), specifying the remote client/port to which the event will be sent. If *$dest\_client* is zero (as generated by ***scoreevent2alsa()*** or ***noteevent()***), or is the same as the local client (as generated by ***input()***), then the event will be sent to all clients that the local port is connected to (see *connectto*() and ***listconnectedto()***). But if you set *dest\_client* to a remote client, then the event will be sent to that *dest\_client:dest\_port* and nowhere else. It is possible to send an event to a destination to which there is no connection, but it's not usually the right thing to do. Normally, you should set up a connection, to allow the underlying RawMIDI ports to remain open while playing - otherwise, ALSA will reset the port after every event. If the queue buffer is full, *output*() will wait until space is available to output the event. Use *status*() to know how many events are scheduled in the queue. If no queue has been started, a SND\_SEQ\_EVENT\_NOTE event can only emerge as a SND\_SEQ\_EVENT\_NOTEON, since a queue is necessary in order to schedule the corresponding NOTEOFF. - **start()** Start the queue. It is ignored if the client does not have a queue. - **status()** Return ($status,$time,$events ) of the queue. ``` Status: 0 if stopped, 1 if running. Time: current time in seconds. Events: number of output events scheduled in the queue. ``` If the client does not have a queue then (0,0,0) is returned. Unlike in the *alsaseq.py* Python module, the *time* element is in floating-point seconds. - **stop()** Stop the queue. It is ignored if the client does not have a queue. - **syncoutput()** Wait until output events are processed. - noteevent( $ch, $key, $vel, $start, $duration ) Returns an ALSA-event-array, to be scheduled by *output*(). Unlike in the *alsaseq.py* Python module, the *start* and *duration* elements are in floating-point seconds. - noteonevent( $ch, $key, $vel, $start ) If *start* is not used, the event will be sent directly. Unlike in the *alsaseq.py* Python module. if *start* is provided, the event will be scheduled in a queue. The *start* element, when provided, is in floating-point seconds. - noteoffevent( $ch, $key, $vel, $start ) If *start* is not used, the event will be sent directly. Unlike in the *alsaseq.py* Python module, if *start* is provided, the event will be scheduled in a queue. The *start* element, when provided, is in floating-point seconds. - pgmchangeevent( $ch, $value, $start ) Returns an ALSA-event-array for a *patch\_change* event to be sent by *output*(). If *start* is not used, the event will be sent directly; if *start* is provided, the event will be scheduled in a queue. Unlike in the *alsaseq.py* Python module, the *start* element, when provided, is in floating-point seconds. - pitchbendevent( $ch, $value, $start ) Returns an ALSA-event-array to be sent by *output*(). The value is from -8192 to 8191. If *start* is not used, the event will be sent directly; if *start* is provided, the event will be scheduled in a queue. Unlike in the *alsaseq.py* Python module, the *start* element, when provided, is in floating-point seconds. - controllerevent( $ch, $controllernum, $value, $start ) Returns an ALSA-event-array to be sent by *output*(). If *start* is not used, the event will be sent directly; if *start* is provided, the event will be scheduled in a queue. Unlike in the *alsaseq.py* Python module, the *start* element, when provided, is in floating-point seconds. - chanpress( $ch, $value, $start ) Returns an ALSA-event-array to be sent by *output*(). If *start* is not used, the event will be sent directly; if *start* is provided, the event will be scheduled in a queue. Unlike in the *alsaseq.py* Python module, the *start* element, when provided, is in floating-point seconds. - sysex( $ch, $string, $start ) Returns an ALSA-event-array to be sent by *output*(). If *start* is not used, the event will be sent directly; if *start* is provided, the event will be scheduled in a queue. The string should start with your Manufacturer ID, but should not contain any of the F0 or F7 bytes, they will be added automatically; indeed the string must not contain any bytes with the top-bit set. - alsa2scoreevent( @alsaevent ) Returns an event in the millisecond-tick score-format used by the *MIDI.lua* and *MIDI.py* modules, based on the score-format in Sean Burke's MIDI-Perl CPAN module. See:\ http://www.pjb.com.au/comp/lua/MIDI.html#events Since it combines a *note\_on* and a *note\_off* event into one note event, it will return *nil* when called with the *note\_on* event; the calling loop must therefore detect *nil* and not, for example, try to index it. - scoreevent2alsa( @event ) Returns an ALSA-event-array to be scheduled in a queue by *output*(). The input is an event in the millisecond-tick score-format used by the *MIDI.lua* and *MIDI.py* modules, based on the score-format in Sean Burke's MIDI-Perl CPAN module. See:\ http://www.pjb.com.au/comp/lua/MIDI.html#events For example:\ output(scoreevent2alsa('note',4000,1000,0,62,110)) Some events in a .mid file have no equivalent real-time-midi event (which is the sort that ALSA deals in); these events will cause **scoreevent2alsa()** to return undef. Therefore if you are going through the events in a midi score converting them with **scoreevent2alsa()**, you should check that the result is not undef before doing anything further. - **listclients()** Returns a hash of the numbers and descriptive strings of all ALSA clients: ``` my %clientnumber2clientname = MIDI::ALSA::listclients(); my %clientname2clientnumber = reverse %clientnumber2clientname; ``` - **listnumports()** Returns a hash of the client-numbers and how many ports they are running, so if a client is running 4 ports they will be numbered 0..3 ``` my %clientnumber2howmanyports = MIDI::ALSA::listnumports(); ``` - **listconnectedto()** Returns a list of arrayrefs, each to a three-element array ( `$outputport`, `$dest_client`, `$dest_port` ) exactly as might have been passed to *connectto*(), or which could be passed to *disconnectto*(). - **listconnectedfrom()** Returns a list of arrayrefs, each to a three-element array ( `$inputport`, `$src_client`, `$src_port` ) exactly as might have been passed to *connectfrom*(), or which could be passed to *disconnectfrom*(). - parse\_address( $client\_name ) Given a string, this function returns a two-integer array ( `$client_number`, `$port_number` ) as might be needed by *connectto*() or *connectfrom*(). For example, even if *client*() has not been called, "24" will return 24,0 and "25:1" will return 25,1 If the local client is running, then **parse\_address()** also looks up names. For example, if `"aconnect -oil"` reveals a *timidity* client: ``` client 128: 'TiMidity' [type=user] ``` then parse\_address("TiM") will return 128,0 and parse\_address("TiMi:1") will return 128,1 because it finds the first client with a start-of-string case-sensitive match to the given name. **parse\_address()** is called automatically by *connectto*(), *connectfrom*(), *disconnectto*() and *disconnectfrom*() if they are called with the third argument undefined. **parse\_address()** was introduced in version 1.11 and is not present in the alsaseq.py Python module. ## CONSTANTS The event-type constants, beginning with SND\_SEQ\_, are available not as scalars, but as module subroutines with empty prototypes. They must therefore be used without a dollar-sign e.g.: ``` if ($event[0] == MIDI::ALSA::SND_SEQ_EVENT_PORT_UNSUBSCRIBED) { ... ``` and sometimes even need an explicit () at the end, e.g.: **MIDI::ALSA::SND\_SEQ\_EVENT\_PORT\_UNSUBSCRIBED()** SND\_SEQ\_EVENT\_BOUNCE SND\_SEQ\_EVENT\_CHANPRESS SND\_SEQ\_EVENT\_CLIENT\_CHANGE SND\_SEQ\_EVENT\_CLIENT\_EXIT SND\_SEQ\_EVENT\_CLIENT\_START SND\_SEQ\_EVENT\_CLOCK SND\_SEQ\_EVENT\_CONTINUE SND\_SEQ\_EVENT\_CONTROL14 SND\_SEQ\_EVENT\_CONTROLLER SND\_SEQ\_EVENT\_ECHO SND\_SEQ\_EVENT\_KEYPRESS SND\_SEQ\_EVENT\_KEYSIGN SND\_SEQ\_EVENT\_NONE SND\_SEQ\_EVENT\_NONREGPARAM SND\_SEQ\_EVENT\_NOTE SND\_SEQ\_EVENT\_NOTEOFF SND\_SEQ\_EVENT\_NOTEON SND\_SEQ\_EVENT\_OSS SND\_SEQ\_EVENT\_PGMCHANGE SND\_SEQ\_EVENT\_PITCHBEND SND\_SEQ\_EVENT\_PORT\_CHANGE SND\_SEQ\_EVENT\_PORT\_EXIT SND\_SEQ\_EVENT\_PORT\_START SND\_SEQ\_EVENT\_PORT\_SUBSCRIBED SND\_SEQ\_EVENT\_PORT\_UNSUBSCRIBED SND\_SEQ\_EVENT\_QFRAME SND\_SEQ\_EVENT\_QUEUE\_SKEW SND\_SEQ\_EVENT\_REGPARAM SND\_SEQ\_EVENT\_RESET SND\_SEQ\_EVENT\_RESULT SND\_SEQ\_EVENT\_SENSING SND\_SEQ\_EVENT\_SETPOS\_TICK SND\_SEQ\_EVENT\_SETPOS\_TIME SND\_SEQ\_EVENT\_SONGPOS SND\_SEQ\_EVENT\_SONGSEL SND\_SEQ\_EVENT\_START SND\_SEQ\_EVENT\_STOP SND\_SEQ\_EVENT\_SYNC\_POS SND\_SEQ\_EVENT\_SYSEX SND\_SEQ\_EVENT\_SYSTEM SND\_SEQ\_EVENT\_TEMPO SND\_SEQ\_EVENT\_TICK SND\_SEQ\_EVENT\_TIMESIGN SND\_SEQ\_EVENT\_TUNE\_REQUEST SND\_SEQ\_EVENT\_USR0 SND\_SEQ\_EVENT\_USR1 SND\_SEQ\_EVENT\_USR2 SND\_SEQ\_EVENT\_USR3 SND\_SEQ\_EVENT\_USR4 SND\_SEQ\_EVENT\_USR5 SND\_SEQ\_EVENT\_USR6 SND\_SEQ\_EVENT\_USR7 SND\_SEQ\_EVENT\_USR8 SND\_SEQ\_EVENT\_USR9 SND\_SEQ\_EVENT\_USR\_VAR0 SND\_SEQ\_EVENT\_USR\_VAR1 SND\_SEQ\_EVENT\_USR\_VAR2 SND\_SEQ\_EVENT\_USR\_VAR3 SND\_SEQ\_EVENT\_USR\_VAR4 SND\_SEQ\_QUEUE\_DIRECT SND\_SEQ\_TIME\_STAMP\_REAL VERSION You should avoid hard-coding their numerical values into your programs; but you may sometimes want to inspect MIDI-ALSA data eg. with Data::Dumper. So, sorted by number as gleaned from the source: ``` 0 SND_SEQ_EVENT_SYSTEM 1 SND_SEQ_EVENT_RESULT 5 SND_SEQ_EVENT_NOTE 6 SND_SEQ_EVENT_NOTEON 7 SND_SEQ_EVENT_NOTEOFF 8 SND_SEQ_EVENT_KEYPRESS 10 SND_SEQ_EVENT_CONTROLLER 11 SND_SEQ_EVENT_PGMCHANGE 12 SND_SEQ_EVENT_CHANPRESS 13 SND_SEQ_EVENT_PITCHBEND 14 SND_SEQ_EVENT_CONTROL14 15 SND_SEQ_EVENT_NONREGPARAM 16 SND_SEQ_EVENT_REGPARAM 20 SND_SEQ_EVENT_SONGPOS 21 SND_SEQ_EVENT_SONGSEL 22 SND_SEQ_EVENT_QFRAME 23 SND_SEQ_EVENT_TIMESIGN 24 SND_SEQ_EVENT_KEYSIGN 30 SND_SEQ_EVENT_START 31 SND_SEQ_EVENT_CONTINUE 32 SND_SEQ_EVENT_STOP 33 SND_SEQ_EVENT_SETPOS_TICK 34 SND_SEQ_EVENT_SETPOS_TIME 35 SND_SEQ_EVENT_TEMPO 36 SND_SEQ_EVENT_CLOCK 37 SND_SEQ_EVENT_TICK 38 SND_SEQ_EVENT_QUEUE_SKEW 39 SND_SEQ_EVENT_SYNC_POS 40 SND_SEQ_EVENT_TUNE_REQUEST 41 SND_SEQ_EVENT_RESET 42 SND_SEQ_EVENT_SENSING 50 SND_SEQ_EVENT_ECHO 51 SND_SEQ_EVENT_OSS 60 SND_SEQ_EVENT_CLIENT_START 61 SND_SEQ_EVENT_CLIENT_EXIT 62 SND_SEQ_EVENT_CLIENT_CHANGE 63 SND_SEQ_EVENT_PORT_START 64 SND_SEQ_EVENT_PORT_EXIT 65 SND_SEQ_EVENT_PORT_CHANGE 66 SND_SEQ_EVENT_PORT_SUBSCRIBED 67 SND_SEQ_EVENT_PORT_UNSUBSCRIBED 90 SND_SEQ_EVENT_USR0 91 SND_SEQ_EVENT_USR1 92 SND_SEQ_EVENT_USR2 93 SND_SEQ_EVENT_USR3 94 SND_SEQ_EVENT_USR4 95 SND_SEQ_EVENT_USR5 96 SND_SEQ_EVENT_USR6 97 SND_SEQ_EVENT_USR7 98 SND_SEQ_EVENT_USR8 99 SND_SEQ_EVENT_USR9 130 SND_SEQ_EVENT_SYSEX 131 SND_SEQ_EVENT_BOUNCE 135 SND_SEQ_EVENT_USR_VAR0 136 SND_SEQ_EVENT_USR_VAR1 137 SND_SEQ_EVENT_USR_VAR2 138 SND_SEQ_EVENT_USR_VAR3 139 SND_SEQ_EVENT_USR_VAR4 255 SND_SEQ_EVENT_NONE ``` The MIDI standard specifies that a NOTEON event with velocity=0 means the same as a NOTEOFF event; so you may find a little subroutine like this convenient: ``` sub is_noteoff { my @alsaevent = @_; if ($alsaevent[0] == MIDI::ALSA::SND_SEQ_EVENT_NOTEOFF()) { return 1; } if ($alsaevent[0] == MIDI::ALSA::SND_SEQ_EVENT_NOTEON() and $alsaevent[7][2] == 0) { return 1; } return 0; } ``` Since Version 1.20, the output-ports are marked as WRITE, so they can receive SND\_SEQ\_EVENT\_PORT\_SUBSCRIBED or SND\_SEQ\_EVENT\_PORT\_UNSUBSCRIBED events from *System Announce*. Up until Version 1.19, and in the original Python module, output-ports created by **client()** were not so marked; in those days, if knowing about connections and disconnections to the output-port was important, you had to listen to all notifications from *System Announce*: `"MIDI::ALSA::connectfrom(0,'System:1')"` This alerted you unnecessarily to events which didn't involve your client, and the connection showed up confusingly in the output of `"aconnect -oil"` ## DOWNLOAD This Perl version is available from CPAN at http://search.cpan.org/perldoc?MIDI::ALSA The Lua module is available as a LuaRock in http://luarocks.org/repositories/rocks/index.html#midi so you should be able to install it with the command:\ \# luarocks install midialsa ## TO DO Perhaps there should be a general **connect\_between()** mechanism, allowing the interconnection of two other clients, a bit like *aconnect 32 20* ALSA does not transmit Meta-Events like *text\_event*, and there's not much can be done about that. ## AUTHOR Peter J Billam, http://www.pjb.com.au/comp/contact.html ## SEE ALSO ``` aconnect -oil http://pp.com.mx/python/alsaseq http://search.cpan.org/perldoc?MIDI::ALSA http://www.pjb.com.au/comp/lua/midialsa.html http://luarocks.org/repositories/rocks/index.html#midialsa http://www.pjb.com.au/comp/lua/MIDI.html http://www.pjb.com.au/comp/lua/MIDI.html#events http://alsa-project.org/alsa-doc/alsa-lib/seq.html http://alsa-project.org/alsa-doc/alsa-lib/structsnd__seq__ev__note.html http://alsa-project.org/alsa-doc/alsa-lib/structsnd__seq__ev__ctrl.html http://alsa-project.org/alsa-doc/alsa-lib/structsnd__seq__ev__queue__control.html http://alsa-project.org/alsa-doc/alsa-lib/group___seq_client.html http://alsa-utils.sourcearchive.com/documentation/1.0.20/aconnect_8c-source.html http://alsa-utils.sourcearchive.com/documentation/1.0.8/aplaymidi_8c-source.html snd_seq_client_info_event_filter_clear snd_seq_get_any_client_info snd_seq_get_client_info snd_seq_client_info_t http://hackage.haskell.org/package/alsa-seq http://search.cpan.org/perldoc?AnyEvent ```