www.linuxsampler.org/api/lscp-1.1.txt



LinuxSampler Developers                                   C. Schoenebeck
Internet-Draft                           Interessengemeinschaft Software
Expires: May 29, 2007                                  Engineering e. V.
                                                       November 25, 2006


                     LinuxSampler Control Protocol
                                LSCP 1.1

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on May 29, 2007.

Copyright Notice

   Copyright (C) The Internet Society (2006).  All Rights Reserved.

Abstract

   The LinuxSampler Control Protocol (LSCP) is an application-level
   protocol primarily intended for local and remote controlling the
   LinuxSampler backend application, which is a sophisticated server-
   like console application essentially playing back audio samples and
   manipulating the samples in real time to certain extent.


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Table of Contents

   1.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  4
   2.  Versioning of this specification . . . . . . . . . . . . . . .  5
   3.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  Focus of this protocol . . . . . . . . . . . . . . . . . . . .  7
   5.  Communication Overview . . . . . . . . . . . . . . . . . . . .  8
     5.1.  Request/response communication method  . . . . . . . . . .  8
       5.1.1.  Result format  . . . . . . . . . . . . . . . . . . . .  9
     5.2.  Subscribe/notify communication method  . . . . . . . . . . 11
   6.  Description for control commands . . . . . . . . . . . . . . . 13
     6.1.  Ignored lines and comments . . . . . . . . . . . . . . . . 13
     6.2.  Configuring audio drivers  . . . . . . . . . . . . . . . . 13
       6.2.1.  Getting amount of available audio output drivers . . . 13
       6.2.2.  Getting all available audio output drivers . . . . . . 14
       6.2.3.  Getting information about a specific audio output
               driver . . . . . . . . . . . . . . . . . . . . . . . . 14
       6.2.4.  Getting information about specific audio output
               driver parameter . . . . . . . . . . . . . . . . . . . 15
       6.2.5.  Creating an audio output device  . . . . . . . . . . . 19
       6.2.6.  Destroying an audio output device  . . . . . . . . . . 20
       6.2.7.  Getting all created audio output device count  . . . . 21
       6.2.8.  Getting all created audio output device list . . . . . 21
       6.2.9.  Getting current settings of an audio output device . . 21
       6.2.10. Changing settings of audio output devices  . . . . . . 23
       6.2.11. Getting information about an audio channel . . . . . . 23
       6.2.12. Getting information about specific audio channel
               parameter  . . . . . . . . . . . . . . . . . . . . . . 25
       6.2.13. Changing settings of audio output channels . . . . . . 27
     6.3.  Configuring MIDI input drivers . . . . . . . . . . . . . . 28
       6.3.1.  Getting amount of available MIDI input drivers . . . . 29
       6.3.2.  Getting all available MIDI input drivers . . . . . . . 29
       6.3.3.  Getting information about a specific MIDI input
               driver . . . . . . . . . . . . . . . . . . . . . . . . 29
       6.3.4.  Getting information about specific MIDI input
               driver parameter . . . . . . . . . . . . . . . . . . . 30
       6.3.5.  Creating a MIDI input device . . . . . . . . . . . . . 33
       6.3.6.  Destroying a MIDI input device . . . . . . . . . . . . 34
       6.3.7.  Getting all created MIDI input device count  . . . . . 35
       6.3.8.  Getting all created MIDI input device list . . . . . . 35
       6.3.9.  Getting current settings of a MIDI input device  . . . 35
       6.3.10. Changing settings of MIDI input devices  . . . . . . . 37
       6.3.11. Getting information about a MIDI port  . . . . . . . . 37
       6.3.12. Getting information about specific MIDI port
               parameter  . . . . . . . . . . . . . . . . . . . . . . 38
       6.3.13. Changing settings of MIDI input ports  . . . . . . . . 40
     6.4.  Configuring sampler channels . . . . . . . . . . . . . . . 41
       6.4.1.  Loading an instrument  . . . . . . . . . . . . . . . . 41


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       6.4.2.  Loading a sampler engine . . . . . . . . . . . . . . . 42
       6.4.3.  Getting all created sampler channel count  . . . . . . 43
       6.4.4.  Getting all created sampler channel list . . . . . . . 43
       6.4.5.  Adding a new sampler channel . . . . . . . . . . . . . 43
       6.4.6.  Removing a sampler channel . . . . . . . . . . . . . . 44
       6.4.7.  Getting amount of available engines  . . . . . . . . . 45
       6.4.8.  Getting all available engines  . . . . . . . . . . . . 45
       6.4.9.  Getting information about an engine  . . . . . . . . . 46
       6.4.10. Getting sampler channel information  . . . . . . . . . 47
       6.4.11. Current number of active voices  . . . . . . . . . . . 50
       6.4.12. Current number of active disk streams  . . . . . . . . 50
       6.4.13. Current fill state of disk stream buffers  . . . . . . 50
       6.4.14. Setting audio output device  . . . . . . . . . . . . . 51
       6.4.15. Setting audio output type  . . . . . . . . . . . . . . 52
       6.4.16. Setting audio output channel . . . . . . . . . . . . . 53
       6.4.17. Setting MIDI input device  . . . . . . . . . . . . . . 54
       6.4.18. Setting MIDI input type  . . . . . . . . . . . . . . . 54
       6.4.19. Setting MIDI input port  . . . . . . . . . . . . . . . 55
       6.4.20. Setting MIDI input channel . . . . . . . . . . . . . . 56
       6.4.21. Setting channel volume . . . . . . . . . . . . . . . . 56
       6.4.22. Muting a sampler channel . . . . . . . . . . . . . . . 57
       6.4.23. Soloing a sampler channel  . . . . . . . . . . . . . . 58
       6.4.24. Resetting a sampler channel  . . . . . . . . . . . . . 58
     6.5.  Controlling connection . . . . . . . . . . . . . . . . . . 59
       6.5.1.  Register front-end for receiving event messages  . . . 59
       6.5.2.  Unregister front-end for not receiving event
               messages . . . . . . . . . . . . . . . . . . . . . . . 60
       6.5.3.  Enable or disable echo of commands . . . . . . . . . . 61
       6.5.4.  Close client connection  . . . . . . . . . . . . . . . 61
     6.6.  Global commands  . . . . . . . . . . . . . . . . . . . . . 61
       6.6.1.  Current number of active voices  . . . . . . . . . . . 61
       6.6.2.  Maximum amount of active voices  . . . . . . . . . . . 62
       6.6.3.  Reset sampler  . . . . . . . . . . . . . . . . . . . . 62
       6.6.4.  General sampler informations . . . . . . . . . . . . . 62
   7.  Command Syntax . . . . . . . . . . . . . . . . . . . . . . . . 64
   8.  Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
     8.1.  Number of sampler channels changed . . . . . . . . . . . . 71
     8.2.  Number of active voices changed  . . . . . . . . . . . . . 71
     8.3.  Number of active disk streams changed  . . . . . . . . . . 71
     8.4.  Disk stream buffer fill state changed  . . . . . . . . . . 72
     8.5.  Channel information changed  . . . . . . . . . . . . . . . 72
     8.6.  Total number of active voices changed  . . . . . . . . . . 72
     8.7.  Miscellaneous and debugging events . . . . . . . . . . . . 73
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 74
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 75
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 75
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 76
   Intellectual Property and Copyright Statements . . . . . . . . . . 77


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1.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   This protocol is always case-sensitive if not explicitly claimed the
   opposite.

   In examples, "C:" and "S:" indicate lines sent by the client (front-
   end) and server (LinuxSampler) respectively.  Lines in examples must
   be interpreted as every line being CRLF terminated (carriage return
   character followed by line feed character as defined in the ASCII
   standard), thus the following example:

      C: "some line"

         "another line"

   must actually be interpreted as client sending the following message:

      "some line<CR><LF>another line<CR><LF>"

   where <CR> symbolizes the carriage return character and <LF> the line
   feed character as defined in the ASCII standard.

   Due to technical reasons, messages can arbitrary be fragmented, means
   the following example:

      S: "abcd"

   could also happen to be sent in three messages like in the following
   sequence scenario:

   o  server sending message "a"

   o  followed by a delay (pause) with arbitrary duration

   o  followed by server sending message "bcd<CR>"

   o  again followed by a delay (pause) with arbitrary duration

   o  followed by server sending the message "<LF>"

   where again <CR> and <LF> symbolize the carriage return and line feed
   characters respectively.


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2.  Versioning of this specification

   LSCP will certainly be extended and enhanced by-and-by.  Each
   official release of the LSCP specification will be tagged with a
   unique version tuple.  The version tuple consists at least of a major
   and minor version number like:

      "1.2"

   In this example the major version number would be "1" and the minor
   version number would be "2".  Note that the version tuple might also
   have more than two elements.  The major version number defines a
   group of backward compatible versions.  That means a frontend is
   compatible to the connected sampler if and only if the LSCP versions
   to which each of the two parties complies to, match both of the
   following rules:

   Compatibility:

   1.  The frontend's LSCP major version and the sampler's LSCP major
       version are exactly equal.

   2.  The frontend's LSCP minor version is less or equal than the
       sampler's LSCP minor version.

   Compatibility can only be claimed if both rules are true.  The
   frontend can use the "GET SERVER INFO" (Section 6.6.4) command to get
   the version of the LSCP specification the sampler complies with.


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3.  Introduction

   LinuxSampler is a so called software sampler application capable to
   playback audio samples from a computer's Random Access Memory (RAM)
   as well as directly streaming it from disk.  LinuxSampler is designed
   to be modular.  It provides several so called "sampler engines" where
   each engine is specialized for a certain purpose.  LinuxSampler has
   virtual channels which will be referred in this document as "sampler
   channels".  The channels are in such way virtual as they can be
   connected to an arbitrary MIDI input method and arbitrary MIDI
   channel (e.g. sampler channel 17 could be connected to an ALSA
   sequencer device 64:0 and listening to MIDI channel 1 there).  Each
   sampler channel will be associated with an instance of one of the
   available sampler engines (e.g.  GigEngine, DLSEngine).  The audio
   output of each sampler channel can be routed to an arbitrary audio
   output method (ALSA / JACK) and an arbitrary audio output channel
   there.


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4.  Focus of this protocol

   Main focus of this protocol is to provide a way to configure a
   running LinuxSampler instance and to retrieve information about it.
   The focus of this protocol is not to provide a way to control
   synthesis parameters or even to trigger or release notes.  Or in
   other words; the focus are those functionalities which are not
   covered by MIDI or which may at most be handled via MIDI System
   Exclusive Messages.


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5.  Communication Overview

   There are two distinct methods of communication between a running
   instance of LinuxSampler and one or more control applications, so
   called "front-ends": a simple request/response communication method
   used by the clients to give commands to the server as well as to
   inquire about server's status and a subscribe/notify communication
   method used by the client to subscribe to and receive notifications
   of certain events as they happen on the server.  The latter needs
   more effort to be implemented in the front-end application.  The two
   communication methods will be described next.

5.1.  Request/response communication method

   This simple communication method is based on TCP [RFC793].  The
   front-end application establishes a TCP connection to the
   LinuxSampler instance on a certain host system.  Then the front-end
   application will send certain ASCII based commands as defined in this
   document (every command line must be CRLF terminated - see
   "Conventions used in this document" at the beginning of this
   document) and the LinuxSampler application will response after a
   certain process time with an appropriate ASCII based answer, also as
   defined in this document.  So this TCP communication is simply based
   on query and answer paradigm.  That way LinuxSampler is only able to
   answer on queries from front-ends, but not able to automatically send
   messages to the client if it's not asked to.  The fronted should not
   reconnect to LinuxSampler for every single command, instead it should
   keep the connection established and simply resend message(s) for
   subsequent commands.  To keep information in the front-end up-to-date
   the front-end has to periodically send new requests to get the
   current information from the LinuxSampler instance.  This is often
   referred to as "polling".  While polling is simple to implement and
   may be OK to use in some cases, there may be disadvantages to polling
   such as network traffic overhead and information being out of date.
   It is possible for a client or several clients to open more than one
   connection to the server at the same time.  It is also possible to
   send more than one request to the server at the same time but if
   those requests are sent over the same connection server MUST execute
   them sequentially.  Upon executing a request server will produce a
   result set and send it to the client.  Each and every request made by
   the client MUST result in a result set being sent back to the client.
   No other data other than a result set may be sent by a server to a
   client.  No result set may be sent to a client without the client
   sending request to the server first.  On any particular connection,
   result sets MUST be sent in their entirety without being interrupted
   by other result sets.  If several requests got queued up at the
   server they MUST be processed in the order they were received and
   result sets MUST be sent back in the same order.


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5.1.1.  Result format

   Result set could be one of the following types:

   1.  Normal

   2.  Warning

   3.  Error

   Warning and Error result sets MUST be single line and have the
   following format:

   o  "WRN:<warning-code>:<warning-message>"

   o  "ERR:<error-code>:<error-message>"

   Where <warning-code> and <error-code> are numeric unique identifiers
   of the warning or error and <warning-message> and <error-message> are
   human readable descriptions of the warning or error respectively.

   Examples:

      C: "LOAD INSTRUMENT '/home/me/Boesendorfer24bit.gig" 0 0

      S: "WRN:32:This is a 24 bit patch which is not supported natively
      yet."

      C: "GET AUDIO_OUTPUT_DRIVER_PARAMETER INFO ALSA EAR"

      S: "ERR:3456:Audio output driver 'ALSA' does not have a parameter
      'EAR'."

      C: "GET AUDIO_OUTPUT_DEVICE INFO 123456"

      S: "ERR:9:There is no audio output device with index 123456."

   Normal result sets could be:

   1.  Empty

   2.  Single line

   3.  Multi-line

   Empty result set is issued when the server only needed to acknowledge
   the fact that the request was received and it was processed
   successfully and no additional information is available.  This result


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   set has the following format:

      "OK"

   Example:

      C: "SET AUDIO_OUTPUT_DEVICE_PARAMETER 0 CHANNELS=4"

      S: "OK"

   Single line result sets are command specific.  One example of a
   single line result set is an empty line.  Multi-line result sets are
   command specific and may include one or more lines of information.
   They MUST always end with the following line:

      "."

   Example:

      C: "GET AUDIO_OUTPUT_DEVICE INFO 0"

      S: "DRIVER: ALSA"

         "CHANNELS: 2"

         "SAMPLERATE: 44100"

         "ACTIVE: true"

         "FRAGMENTS: 2"

         "FRAGMENTSIZE: 128"

         "CARD: '0,0'"

         "."

   In addition to above mentioned formats, warnings and empty result
   sets MAY be indexed.  In this case, they have the following formats
   respectively:

   o  "WRN[<index>]:<warning-code>:<warning-message>"

   o  "OK[<index>]"

   where <index> is command specific and is used to indicate channel
   number that the result set was related to or other integer value.


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   Each line of the result set MUST end with <CRLF>.

   Examples:

      C: "ADD CHANNEL"

      S: "OK[12]"

      C: "CREATE AUDIO_OUTPUT_DEVICE ALSA SAMPLERATE=96000"

      S: "WRN[0]:32:Sample rate not supported, using 44100 instead."

5.2.  Subscribe/notify communication method

   This more sophisticated communication method is actually only an
   extension of the simple request/response communication method.  The
   front-end still uses a TCP connection and sends the same commands on
   the TCP connection.  Two extra commands are SUBSCRIBE and UNSUBSCRIBE
   commands that allow a client to tell the server that it is interested
   in receiving notifications about certain events as they happen on the
   server.  The SUBSCRIBE command has the following syntax:

      SUBSCRIBE <event-id>

   where <event-id> will be replaced by the respective event that client
   wants to subscribe to.  Upon receiving such request, server SHOULD
   respond with OK and start sending EVENT notifications when a given
   even has occurred to the front-end when an event has occurred.  It
   MAY be possible certain events may be sent before OK response during
   real time nature of their generation.  Event messages have the
   following format:

      NOTIFY:<event-id>:<custom-event-data>

   where <event-id> uniquely identifies the event that has occurred and
   <custom-event-data> is event specific.

   Several rules must be followed by the server when generating events:

   1.  Events MUST NOT be sent to any client who has not issued an
       appropriate SUBSCRIBE command.

   2.  Events MUST only be sent using the same connection that was used
       to subscribe to them.

   3.  When response is being sent to the client, event MUST be inserted
       in the stream before or after the response, but NOT in the
       middle.  Same is true about the response.  It should never be


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       inserted in the middle of the event message as well as any other
       response.

   If the client is not interested in a particular event anymore it MAY
   issue UNSUBSCRIBE command using the following syntax:

      UNSUBSCRIBE <event-id>

   where <event-id> will be replace by the respective event that client
   is no longer interested in receiving.  For a list of supported events
   see Section 8.

   Example: the fill states of disk stream buffers have changed on
   sampler channel 4 and the LinuxSampler instance will react by sending
   the following message to all clients who subscribed to this event:

      NOTIFY:CHANNEL_BUFFER_FILL:4 [35]62%,[33]80%,[37]98%

   Which means there are currently three active streams on sampler
   channel 4, where the stream with ID "35" is filled by 62%, stream
   with ID 33 is filled by 80% and stream with ID 37 is filled by 98%.

   Clients may choose to open more than one connection to the server and
   use some connections to receive notifications while using other
   connections to issue commands to the back-end.  This is entirely
   legal and up to the implementation.  This does not change the
   protocol in any way and no special restrictions exist on the server
   to allow or disallow this or to track what connections belong to what
   front-ends.  Server will listen on a single port, accept multiple
   connections and support protocol described in this specification in
   it's entirety on this single port on each connection that it
   accepted.

   Due to the fact that TCP is used for this communication, dead peers
   will be detected automatically by the OS TCP stack.  While it may
   take a while to detect dead peers if no traffic is being sent from
   server to client (TCP keep-alive timer is set to 2 hours on many
   OSes) it will not be an issue here as when notifications are sent by
   the server, dead client will be detected quickly.

   When connection is closed for any reason server MUST forget all
   subscriptions that were made on this connection.  If client
   reconnects it MUST resubscribe to all events that it wants to
   receive.


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6.  Description for control commands

   This chapter will describe the available control commands that can be
   sent on the TCP connection in detail.  Some certain commands (e.g.
   "GET CHANNEL INFO" (Section 6.4.10) or "GET ENGINE INFO"
   (Section 6.4.9)) lead to multiple-line responses.  In this case
   LinuxSampler signals the end of the response by a "." (single dot)
   line.

6.1.  Ignored lines and comments

   White lines, that is lines which only contain space and tabulator
   characters, and lines that start with a "#" character are ignored,
   thus it's possible for example to group commands and to place
   comments in a LSCP script file.

6.2.  Configuring audio drivers

   Instances of drivers in LinuxSampler are called devices.  You can use
   multiple audio devices simultaneously, e.g. to output the sound of
   one sampler channel using the ALSA audio output driver, and on
   another sampler channel you might want to use the JACK audio output
   driver.  For particular audio output systems it's also possible to
   create several devices of the same audio output driver, e.g. two
   separate ALSA audio output devices for using two different sound
   cards at the same time.  This chapter describes all commands to
   configure LinuxSampler's audio output devices and their parameters.

   Instead of defining commands and parameters for each driver
   individually, all possible parameters, their meanings and possible
   values have to be obtained at runtime.  This makes the protocol a bit
   abstract, but has the advantage, that front-ends can be written
   independently of what drivers are currently implemented and what
   parameters these drivers are actually offering.  This means front-
   ends can even handle drivers which are implemented somewhere in
   future without modifying the front-end at all.

   Note: examples in this chapter showing particular parameters of
   drivers are not meant as specification of the drivers' parameters.
   Driver implementations in LinuxSampler might have complete different
   parameter names and meanings than shown in these examples or might
   change in future, so these examples are only meant for showing how to
   retrieve what parameters drivers are offering, how to retrieve their
   possible values, etc.

6.2.1.  Getting amount of available audio output drivers

   Use the following command to get the number of audio output drivers


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   currently available for the LinuxSampler instance:

      GET AVAILABLE_AUDIO_OUTPUT_DRIVERS

   Possible Answers:

      LinuxSampler will answer by sending the number of audio output
      drivers.

   Example:

      C: "GET AVAILABLE_AUDIO_OUTPUT_DRIVERS"

      S: "2"

6.2.2.  Getting all available audio output drivers

   Use the following command to list all audio output drivers currently
   available for the LinuxSampler instance:

      LIST AVAILABLE_AUDIO_OUTPUT_DRIVERS

   Possible Answers:

      LinuxSampler will answer by sending comma separated character
      strings, each symbolizing an audio output driver.

   Example:

      C: "LIST AVAILABLE_AUDIO_OUTPUT_DRIVERS"

      S: "ALSA,JACK"

6.2.3.  Getting information about a specific audio output driver

   Use the following command to get detailed information about a
   specific audio output driver:

      GET AUDIO_OUTPUT_DRIVER INFO <audio-output-driver>

   Where <audio-output-driver> is the name of the audio output driver,
   returned by the "LIST AVAILABLE_AUDIO_OUTPUT_DRIVERS" (Section 6.2.2)
   command.

   Possible Answers:


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      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  At the moment the
      following information categories are defined:


         DESCRIPTION -

            character string describing the audio output driver

         VERSION -

            character string reflecting the driver's version

         PARAMETERS -

            comma separated list of all parameters available for the
            given audio output driver, at least parameters 'channels',
            'samplerate' and 'active' are offered by all audio output
            drivers

      The mentioned fields above don't have to be in particular order.

   Example:

      C: "GET AUDIO_OUTPUT_DRIVER INFO ALSA"

      S: "DESCRIPTION: Advanced Linux Sound Architecture"

         "VERSION: 1.0"

         "PARAMETERS: DRIVER,CHANNELS,SAMPLERATE,ACTIVE,FRAGMENTS,
      FRAGMENTSIZE,CARD"

         "."

6.2.4.  Getting information about specific audio output driver parameter

   Use the following command to get detailed information about a
   specific audio output driver parameter:

      GET AUDIO_OUTPUT_DRIVER_PARAMETER INFO <audio> <prm> [<deplist>]

   Where <audio> is the name of the audio output driver as returned by
   the "LIST AVAILABLE_AUDIO_OUTPUT_DRIVERS" (Section 6.2.2) command,
   <prm> a specific parameter name for which information should be


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   obtained (as returned by the "GET AUDIO_OUTPUT_DRIVER INFO"
   (Section 6.2.3) command) and <deplist> is an optional list of
   parameters on which the sought parameter <prm> depends on, <deplist>
   is a list of key-value pairs in form of "key1=val1 key2=val2 ...",
   where character string values are encapsulated into apostrophes (').
   Arguments given with <deplist> which are not dependency parameters of
   <prm> will be ignored, means the front-end application can simply put
   all parameters into <deplist> with the values already selected by the
   user.

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  There are information
      which is always returned, independently of the given driver
      parameter and there are optional information which is only shown
      dependently to given driver parameter.  At the moment the
      following information categories are defined:

      TYPE -

         either "BOOL" for boolean value(s) or "INT" for integer
         value(s) or "FLOAT" for dotted number(s) or "STRING" for
         character string(s) (always returned, no matter which driver
         parameter)

      DESCRIPTION -

         arbitrary text describing the purpose of the parameter (always
         returned, no matter which driver parameter)

      MANDATORY -

         either true or false, defines if this parameter must be given
         when the device is to be created with the 'CREATE
         AUDIO_OUTPUT_DEVICE' (Section 6.2.5) command (always returned,
         no matter which driver parameter)

      FIX -

         either true or false, if false then this parameter can be
         changed at any time, once the device is created by the 'CREATE
         AUDIO_OUTPUT_DEVICE' (Section 6.2.5) command (always returned,
         no matter which driver parameter)


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      MULTIPLICITY -

         either true or false, defines if this parameter allows only one
         value or a list of values, where true means multiple values and
         false only a single value allowed (always returned, no matter
         which driver parameter)

      DEPENDS -

         comma separated list of parameters this parameter depends on,
         means the values for fields 'DEFAULT', 'RANGE_MIN', 'RANGE_MAX'
         and 'POSSIBILITIES' might depend on these listed parameters,
         for example assuming that an audio driver (like the ALSA
         driver) offers parameters 'card' and 'samplerate' then
         parameter 'samplerate' would depend on 'card' because the
         possible values for 'samplerate' depends on the sound card
         which can be chosen by the 'card' parameter (optionally
         returned, dependent to driver parameter)

      DEFAULT -

         reflects the default value for this parameter which is used
         when the device is created and not explicitly given with the
         'CREATE AUDIO_OUTPUT_DEVICE' (Section 6.2.5) command, in case
         of MULTIPLCITY=true, this is a comma separated list, that's why
         character strings are encapsulated into apostrophes (')
         (optionally returned, dependent to driver parameter)

      RANGE_MIN -

         defines lower limit of the allowed value range for this
         parameter, can be an integer value as well as a dotted number,
         this parameter is often used in conjunction with RANGE_MAX, but
         may also appear without (optionally returned, dependent to
         driver parameter)

      RANGE_MAX -

         defines upper limit of the allowed value range for this
         parameter, can be an integer value as well as a dotted number,
         this parameter is often used in conjunction with RANGE_MIN, but
         may also appear without (optionally returned, dependent to
         driver parameter)

      POSSIBILITIES -

         comma separated list of possible values for this parameter,
         character strings are encapsulated into apostrophes (optionally


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         returned, dependent to driver parameter)

   The mentioned fields above don't have to be in particular order.

   Examples:

      C: "GET AUDIO_OUTPUT_DRIVER_PARAMETER INFO ALSA CARD"

      S: "DESCRIPTION: sound card to be used"

         "TYPE: STRING"

         "MANDATORY: false"

         "FIX: true"

         "MULTIPLICITY: false"

         "DEFAULT: '0,0'"

         "POSSIBILITIES: '0,0','1,0','2,0'"

         "."

      C: "GET AUDIO_OUTPUT_DRIVER_PARAMETER INFO ALSA SAMPLERATE"

      S: "DESCRIPTION: output sample rate in Hz"

         "TYPE: INT"

         "MANDATORY: false"

         "FIX: false"

         "MULTIPLICITY: false"

         "DEPENDS: card"

         "DEFAULT: 44100"

         "."

      C: "GET AUDIO_OUTPUT_DRIVER_PARAMETER INFO ALSA SAMPLERATE
      CARD='0,0'"

      S: "DESCRIPTION: output sample rate in Hz"


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         "TYPE: INT"

         "MANDATORY: false"

         "FIX: false"

         "MULTIPLICITY: false"

         "DEPENDS: card"

         "DEFAULT: 44100"

         "RANGE_MIN: 22050"

         "RANGE_MAX: 96000"

         "."

6.2.5.  Creating an audio output device

   Use the following command to create a new audio output device for the
   desired audio output system:

      CREATE AUDIO_OUTPUT_DEVICE <audio-output-driver> [<param-list>]

   Where <audio-output-driver> should be replaced by the desired audio
   output system as returned by the "LIST
   AVAILABLE_AUDIO_OUTPUT_DRIVERS" (Section 6.2.2) command and <param-
   list> by an optional list of driver specific parameters in form of
   "key1=val1 key2=val2 ...", where character string values should be
   encapsulated into apostrophes (').  Note that there might be drivers
   which require parameter(s) to be given with this command.  Use the
   previously described commands in this chapter to get this
   information.

   Possible Answers:

      "OK[<device-id>]" -

         in case the device was successfully created, where <device-id>
         is the numerical ID of the new device

      "WRN[<device-id>]:<warning-code>:<warning-message>" -

         in case the device was created successfully, where <device-id>
         is the numerical ID of the new device, but there are noteworthy
         issue(s) related (e.g. sound card doesn't support given
         hardware parameters and the driver is using fall-back values),


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         providing an appropriate warning code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:

      C: "CREATE AUDIO_OUTPUT_DEVICE ALSA"

      S: "OK[0]"

      C: "CREATE AUDIO_OUTPUT_DEVICE ALSA CARD='2,0' SAMPLERATE=96000"

      S: "OK[1]"

6.2.6.  Destroying an audio output device

   Use the following command to destroy a created output device:

      DESTROY AUDIO_OUTPUT_DEVICE <device-id>

   Where <device-id> should be replaced by the numerical ID of the audio
   output device as given by the "CREATE AUDIO_OUTPUT_DEVICE"
   (Section 6.2.5) or "LIST AUDIO_OUTPUT_DEVICES" (Section 6.2.8)
   command.

   Possible Answers:

      "OK" -

         in case the device was successfully destroyed

      "WRN:<warning-code>:<warning-message>" -

         in case the device was destroyed successfully, but there are
         noteworthy issue(s) related (e.g. an audio over ethernet driver
         was unloaded but the other host might not be informed about
         this situation), providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


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      C: "DESTROY AUDIO_OUTPUT_DEVICE 0"

      S: "OK"

6.2.7.  Getting all created audio output device count

   Use the following command to count all created audio output devices:

      GET AUDIO_OUTPUT_DEVICES

   Possible Answers:

      LinuxSampler will answer by sending the current number of all
      audio output devices.

   Example:

      C: "GET AUDIO_OUTPUT_DEVICES"

      S: "4"

6.2.8.  Getting all created audio output device list

   Use the following command to list all created audio output devices:

      LIST AUDIO_OUTPUT_DEVICES

   Possible Answers:

      LinuxSampler will answer by sending a comma separated list with
      the numerical IDs of all audio output devices.

   Example:

      C: "LIST AUDIO_OUTPUT_DEVICES"

      S: "0,1,4,5"

6.2.9.  Getting current settings of an audio output device

   Use the following command to get current settings of a specific,
   created audio output device:

      GET AUDIO_OUTPUT_DEVICE INFO <device-id>

   Where <device-id> should be replaced by numerical ID of the audio
   output device as e.g. returned by the "LIST AUDIO_OUTPUT_DEVICES"
   (Section 6.2.8) command.


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   Possible Answers:

   LinuxSampler will answer by sending a <CRLF> separated list.  Each
   answer line begins with the information category name followed by a
   colon and then a space character <SP> and finally the info character
   string to that info category.  As some parameters might allow
   multiple values, character strings are encapsulated into apostrophes
   (').  At the moment the following information categories are defined
   (independently of device):

      DRIVER -

         identifier of the used audio output driver, as also returned by
         the "LIST AVAILABLE_AUDIO_OUTPUT_DRIVERS" (Section 6.2.2)
         command

      CHANNELS -

         amount of audio output channels this device currently offers

      SAMPLERATE -

         playback sample rate the device uses

      ACTIVE -

         either true or false, if false then the audio device is
         inactive and doesn't output any sound, nor do the sampler
         channels connected to this audio device render any audio

   The mentioned fields above don't have to be in particular order.  The
   fields above are only those fields which are returned by all audio
   output devices.  Every audio output driver might have its own,
   additional driver specific parameters (see Section 6.2.3) which are
   also returned by this command.

   Example:

      C: "GET AUDIO_OUTPUT_DEVICE INFO 0"

      S: "DRIVER: ALSA"

         "CHANNELS: 2"

         "SAMPLERATE: 44100"

         "ACTIVE: true"


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         "FRAGMENTS: 2"

         "FRAGMENTSIZE: 128"

         "CARD: '0,0'"

         "."

6.2.10.  Changing settings of audio output devices

   Use the following command to alter a specific setting of a created
   audio output device:

      SET AUDIO_OUTPUT_DEVICE_PARAMETER <device-id> <key>=<value>

   Where <device-id> should be replaced by the numerical ID of the audio
   output device as given by the "CREATE AUDIO_OUTPUT_DEVICE"
   (Section 6.2.5) or "LIST AUDIO_OUTPUT_DEVICES" (Section 6.2.8)
   command, <key> by the name of the parameter to change and <value> by
   the new value for this parameter.

   Possible Answers:

      "OK" -

         in case setting was successfully changed

      "WRN:<warning-code>:<warning-message>" -

         in case setting was changed successfully, but there are
         noteworthy issue(s) related, providing an appropriate warning
         code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:

      C: "SET AUDIO_OUTPUT_DEVICE_PARAMETER 0 FRAGMENTSIZE=128"

      S: "OK"

6.2.11.  Getting information about an audio channel

   Use the following command to get information about an audio channel:


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      GET AUDIO_OUTPUT_CHANNEL INFO <device-id> <audio-chan>

   Where <device-id> is the numerical ID of the audio output device as
   given by the "CREATE AUDIO_OUTPUT_DEVICE" (Section 6.2.5) or "LIST
   AUDIO_OUTPUT_DEVICES" (Section 6.2.8) command and <audio-chan> the
   audio channel number.

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  At the moment the
      following information categories are defined:


         NAME -

            arbitrary character string naming the channel, which doesn't
            have to be unique (always returned by all audio channels)

         IS_MIX_CHANNEL -

            either true or false, a mix-channel is not a real,
            independent audio channel, but a virtual channel which is
            mixed to another real channel, this mechanism is needed for
            sampler engines which need more audio channels than the used
            audio system might be able to offer (always returned by all
            audio channels)

         MIX_CHANNEL_DESTINATION -

            numerical ID (positive integer including 0) which reflects
            the real audio channel (of the same audio output device)
            this mix channel refers to, means where the audio signal
            actually will be routed / added to (only returned in case
            the audio channel is mix channel)

   The mentioned fields above don't have to be in particular order.  The
   fields above are only those fields which are generally returned for
   the described cases by all audio channels regardless of the audio
   driver.  Every audio channel might have its own, additional driver
   and channel specific parameters.

   Examples:


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      C: "GET AUDIO_OUTPUT_CHANNEL INFO 0 0"

      S: "NAME: studio monitor left"

         "IS_MIX_CHANNEL: false"

         "."

      C: "GET AUDIO_OUTPUT_CHANNEL INFO 0 1"

      S: "NAME: studio monitor right"

         "IS_MIX_CHANNEL: false"

         "."

      C: "GET AUDIO_OUTPUT_CHANNEL INFO 0 2"

      S: "NAME: studio monitor left"

         "IS_MIX_CHANNEL: true"

         "MIX_CHANNEL_DESTINATION: 1"

         "."

      C: "GET AUDIO_OUTPUT_CHANNEL INFO 1 0"

      S: "NAME: 'ardour (left)'"

         "IS_MIX_CHANNEL: false"

         "JACK_BINDINGS: 'ardour:0'"

         "."

6.2.12.  Getting information about specific audio channel parameter

   Use the following command to get detailed information about specific
   audio channel parameter:

      GET AUDIO_OUTPUT_CHANNEL_PARAMETER INFO <dev-id> <chan> <param>

   Where <dev-id> is the numerical ID of the audio output device as
   returned by the "CREATE AUDIO_OUTPUT_DEVICE" (Section 6.2.5) or "LIST
   AUDIO_OUTPUT_DEVICES" (Section 6.2.8) command, <chan> the audio
   channel number and <param> a specific channel parameter name for
   which information should be obtained (as returned by the "GET


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   AUDIO_OUTPUT_CHANNEL INFO" (Section 6.2.11) command).

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  There are information
      which is always returned, independently of the given channel
      parameter and there is optional information which is only shown
      dependently to the given audio channel.  At the moment the
      following information categories are defined:


         TYPE -

            either "BOOL" for boolean value(s) or "INT" for integer
            value(s) or "FLOAT" for dotted number(s) or "STRING" for
            character string(s) (always returned)

         DESCRIPTION -

            arbitrary text describing the purpose of the parameter
            (always returned)

         FIX -

            either true or false, if true then this parameter is read
            only, thus cannot be altered (always returned)

         MULTIPLICITY -

            either true or false, defines if this parameter allows only
            one value or a list of values, where true means multiple
            values and false only a single value allowed (always
            returned)

         RANGE_MIN -

            defines lower limit of the allowed value range for this
            parameter, can be an integer value as well as a dotted
            number, usually used in conjunction with 'RANGE_MAX', but
            may also appear without (optionally returned, dependent to
            driver and channel parameter)


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         RANGE_MAX -

            defines upper limit of the allowed value range for this
            parameter, can be an integer value as well as a dotted
            number, usually used in conjunction with 'RANGE_MIN', but
            may also appear without (optionally returned, dependent to
            driver and channel parameter)

         POSSIBILITIES -

            comma separated list of possible values for this parameter,
            character strings are encapsulated into apostrophes
            (optionally returned, dependent to driver and channel
            parameter)

      The mentioned fields above don't have to be in particular order.

   Example:

      C: "GET AUDIO_OUTPUT_CHANNEL_PARAMETER INFO 1 0 JACK_BINDINGS"

      S: "DESCRIPTION: bindings to other JACK clients"

         "TYPE: STRING"

         "FIX: false"

         "MULTIPLICITY: true"

         "POSSIBILITIES: 'PCM:0','PCM:1','ardour:0','ardour:1'"

         "."

6.2.13.  Changing settings of audio output channels

   Use the following command to alter a specific setting of an audio
   output channel:

      SET AUDIO_OUTPUT_CHANNEL_PARAMETER <dev-id> <chn> <key>=<value>

   Where <dev-id> should be replaced by the numerical ID of the audio
   output device as returned by the "CREATE AUDIO_OUTPUT_DEVICE"
   (Section 6.2.5) or "LIST AUDIO_OUTPUT_DEVICES" (Section 6.2.8)
   command, <chn> by the audio channel number, <key> by the name of the
   parameter to change and <value> by the new value for this parameter.

   Possible Answers:


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      "OK" -

         in case setting was successfully changed

      "WRN:<warning-code>:<warning-message>" -

         in case setting was changed successfully, but there are
         noteworthy issue(s) related, providing an appropriate warning
         code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:

      C: "SET AUDIO_OUTPUT_CHANNEL PARAMETER 0 0 JACK_BINDINGS='PCM:0'"

      S: "OK"

      C: "SET AUDIO_OUTPUT_CHANNEL PARAMETER 0 0 NAME='monitor left'"

      S: "OK"

6.3.  Configuring MIDI input drivers

   Instances of drivers in LinuxSampler are called devices.  You can use
   multiple MIDI devices simultaneously, e.g. to use MIDI over ethernet
   as MIDI input on one sampler channel and ALSA as MIDI input on
   another sampler channel.  For particular MIDI input systems it's also
   possible to create several devices of the same MIDI input type.  This
   chapter describes all commands to configure LinuxSampler's MIDI input
   devices and their parameters.

   Instead of defining commands and parameters for each driver
   individually, all possible parameters, their meanings and possible
   values have to be obtained at runtime.  This makes the protocol a bit
   abstract, but has the advantage, that front-ends can be written
   independently of what drivers are currently implemented and what
   parameters these drivers are actually offering.  This means front-
   ends can even handle drivers which are implemented somewhere in
   future without modifying the front-end at all.

   Commands for configuring MIDI input devices are pretty much the same
   as the commands for configuring audio output drivers, already
   described in the last chapter.


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   Note: examples in this chapter showing particular parameters of
   drivers are not meant as specification of the drivers' parameters.
   Driver implementations in LinuxSampler might have complete different
   parameter names and meanings than shown in these examples or might
   change in future, so these examples are only meant for showing how to
   retrieve what parameters drivers are offering, how to retrieve their
   possible values, etc.

6.3.1.  Getting amount of available MIDI input drivers

   Use the following command to get the number of MIDI input drivers
   currently available for the LinuxSampler instance:

      GET AVAILABLE_MIDI_INPUT_DRIVERS

   Possible Answers:

      LinuxSampler will answer by sending the number of available MIDI
      input drivers.

   Example:

      C: "GET AVAILABLE_MIDI_INPUT_DRIVERS"

      S: "2"

6.3.2.  Getting all available MIDI input drivers

   Use the following command to list all MIDI input drivers currently
   available for the LinuxSampler instance:

      LIST AVAILABLE_MIDI_INPUT_DRIVERS

   Possible Answers:

      LinuxSampler will answer by sending comma separated character
      strings, each symbolizing a MIDI input driver.

   Example:

      C: "LIST AVAILABLE_MIDI_INPUT_DRIVERS"

      S: "ALSA,JACK"

6.3.3.  Getting information about a specific MIDI input driver

   Use the following command to get detailed information about a
   specific MIDI input driver:


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      GET MIDI_INPUT_DRIVER INFO <midi-input-driver>

   Where <midi-input-driver> is the name of the MIDI input driver as
   returned by the "LIST AVAILABLE_MIDI_INPUT_DRIVERS" (Section 6.3.2)
   command.

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  At the moment the
      following information categories are defined:


         DESCRIPTION -

            arbitrary description text about the MIDI input driver

         VERSION -

            arbitrary character string regarding the driver's version

         PARAMETERS -

            comma separated list of all parameters available for the
            given MIDI input driver

      The mentioned fields above don't have to be in particular order.

   Example:

      C: "GET MIDI_INPUT_DRIVER INFO ALSA"

      S: "DESCRIPTION: Advanced Linux Sound Architecture"

         "VERSION: 1.0"

         "PARAMETERS: DRIVER,ACTIVE"

         "."

6.3.4.  Getting information about specific MIDI input driver parameter

   Use the following command to get detailed information about a
   specific parameter of a specific MIDI input driver:


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      GET MIDI_INPUT_DRIVER_PARAMETER INFO <midit> <param> [<deplist>]

   Where <midit> is the name of the MIDI input driver as returned by the
   "LIST AVAILABLE_MIDI_INPUT_DRIVERS" (Section 6.3.2) command, <param>
   a specific parameter name for which information should be obtained
   (as returned by the "GET MIDI_INPUT_DRIVER INFO" (Section 6.3.3)
   command) and <deplist> is an optional list of parameters on which the
   sought parameter <param> depends on, <deplist> is a key-value pair
   list in form of "key1=val1 key2=val2 ...", where character string
   values are encapsulated into apostrophes (').  Arguments given with
   <deplist> which are not dependency parameters of <param> will be
   ignored, means the front-end application can simply put all
   parameters in <deplist> with the values selected by the user.

   Possible Answers:

   LinuxSampler will answer by sending a <CRLF> separated list.  Each
   answer line begins with the information category name followed by a
   colon and then a space character <SP> and finally the info character
   string to that info category.  There is information which is always
   returned, independent of the given driver parameter and there is
   optional information which is only shown dependent to given driver
   parameter.  At the moment the following information categories are
   defined:

      TYPE -

         either "BOOL" for boolean value(s) or "INT" for integer
         value(s) or "FLOAT" for dotted number(s) or "STRING" for
         character string(s) (always returned, no matter which driver
         parameter)

      DESCRIPTION -

         arbitrary text describing the purpose of the parameter (always
         returned, no matter which driver parameter)

      MANDATORY -

         either true or false, defines if this parameter must be given
         when the device is to be created with the 'CREATE
         MIDI_INPUT_DEVICE' (Section 6.3.5) command (always returned, no
         matter which driver parameter)

      FIX -

         either true or false, if false then this parameter can be
         changed at any time, once the device is created by the 'CREATE


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         MIDI_INPUT_DEVICE' (Section 6.3.5) command (always returned, no
         matter which driver parameter)

      MULTIPLICITY -

         either true or false, defines if this parameter allows only one
         value or a list of values, where true means multiple values and
         false only a single value allowed (always returned, no matter
         which driver parameter)

      DEPENDS -

         comma separated list of parameters this parameter depends on,
         means the values for fields 'DEFAULT', 'RANGE_MIN', 'RANGE_MAX'
         and 'POSSIBILITIES' might depend on these listed parameters,
         for example assuming that an audio driver (like the ALSA
         driver) offers parameters 'card' and 'samplerate' then
         parameter 'samplerate' would depend on 'card' because the
         possible values for 'samplerate' depends on the sound card
         which can be chosen by the 'card' parameter (optionally
         returned, dependent to driver parameter)

      DEFAULT -

         reflects the default value for this parameter which is used
         when the device is created and not explicitly given with the
         'CREATE MIDI_INPUT_DEVICE' (Section 6.3.5) command, in case of
         MULTIPLCITY=true, this is a comma separated list, that's why
         character strings are encapsulated into apostrophes (')
         (optionally returned, dependent to driver parameter)

      RANGE_MIN -

         defines lower limit of the allowed value range for this
         parameter, can be an integer value as well as a dotted number,
         this parameter is often used in conjunction with RANGE_MAX, but
         may also appear without (optionally returned, dependent to
         driver parameter)

      RANGE_MAX -

         defines upper limit of the allowed value range for this
         parameter, can be an integer value as well as a dotted number,
         this parameter is often used in conjunction with RANGE_MIN, but
         may also appear without (optionally returned, dependent to
         driver parameter)


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      POSSIBILITIES -

         comma separated list of possible values for this parameter,
         character strings are encapsulated into apostrophes (optionally
         returned, dependent to driver parameter)

   The mentioned fields above don't have to be in particular order.

   Example:

      C: "GET MIDI_INPUT_DRIVER_PARAMETER INFO ALSA ACTIVE"

      S: "DESCRIPTION: Whether device is enabled"

         "TYPE: BOOL"

         "MANDATORY: false"

         "FIX: false"

         "MULTIPLICITY: false"

         "DEFAULT: true"

         "."

6.3.5.  Creating a MIDI input device

   Use the following command to create a new MIDI input device for the
   desired MIDI input system:

      CREATE MIDI_INPUT_DEVICE <midi-input-driver> [<param-list>]

   Where <midi-input-driver> should be replaced by the desired MIDI
   input system as returned by the "LIST AVAILABLE_MIDI_INPUT_DRIVERS"
   (Section 6.3.2) command and <param-list> by an optional list of
   driver specific parameters in form of "key1=val1 key2=val2 ...",
   where character string values should be encapsulated into apostrophes
   (').  Note that there might be drivers which require parameter(s) to
   be given with this command.  Use the previously described commands in
   this chapter to get that information.

   Possible Answers:

      "OK[<device-id>]" -

         in case the device was successfully created, where <device-id>
         is the numerical ID of the new device


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      "WRN[<device-id>]:<warning-code>:<warning-message>" -

         in case the driver was loaded successfully, where <device-id>
         is the numerical ID of the new device, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:

      C: "CREATE MIDI_INPUT_DEVICE ALSA"

      S: "OK[0]"

6.3.6.  Destroying a MIDI input device

   Use the following command to destroy a created MIDI input device:

      DESTROY MIDI_INPUT_DEVICE <device-id>

   Where <device-id> should be replaced by the device's numerical ID as
   returned by the "CREATE MIDI_INPUT_DEVICE" (Section 6.3.5) or "LIST
   MIDI_INPUT_DEVICES" (Section 6.3.8) command.

   Possible Answers:

      "OK" -

         in case the device was successfully destroyed

      "WRN:<warning-code>:<warning-message>" -

         in case the device was destroyed, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


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      C: "DESTROY MIDI_INPUT_DEVICE 0"

      S: "OK"

6.3.7.  Getting all created MIDI input device count

   Use the following command to count all created MIDI input devices:

      GET MIDI_INPUT_DEVICES

   Possible Answers:

      LinuxSampler will answer by sending the current number of all MIDI
      input devices.

   Example:

      C: "GET MIDI_INPUT_DEVICES"

      S: "3"

6.3.8.  Getting all created MIDI input device list

   Use the following command to list all created MIDI input devices:

      LIST MIDI_INPUT_DEVICES

   Possible Answers:

      LinuxSampler will answer by sending a comma separated list with
      the numerical Ids of all created MIDI input devices.

   Examples:

      C: "LIST MIDI_INPUT_DEVICES"

      S: "0,1,2"

      C: "LIST MIDI_INPUT_DEVICES"

      S: "1,3"

6.3.9.  Getting current settings of a MIDI input device

   Use the following command to get current settings of a specific,
   created MIDI input device:


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      GET MIDI_INPUT_DEVICE INFO <device-id>

   Where <device-id> is the numerical ID of the MIDI input device as
   returned by the "CREATE MIDI_INPUT_DEVICE" (Section 6.3.5) or "LIST
   MIDI_INPUT_DEVICES" (Section 6.3.8) command.

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  As some parameters might
      allow multiple values, character strings are encapsulated into
      apostrophes (').  At the moment the following information
      categories are defined (independent of driver):


         DRIVER -

            identifier of the used MIDI input driver, as e.g. returned
            by the "LIST AVAILABLE_MIDI_INPUT_DRIVERS" (Section 6.3.2)
            command

         ACTIVE -

            either true or false, if false then the MIDI device is
            inactive and doesn't listen to any incoming MIDI events and
            thus doesn't forward them to connected sampler channels

   The mentioned fields above don't have to be in particular order.  The
   fields above are only those fields which are returned by all MIDI
   input devices.  Every MIDI input driver might have its own,
   additional driver specific parameters (see "GET MIDI_INPUT_DRIVER
   INFO" (Section 6.3.3) command) which are also returned by this
   command.

   Example:

      C: "GET MIDI_INPUT_DEVICE INFO 0"

      S: "DRIVER: ALSA"

         "ACTIVE: true"

         "."


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6.3.10.  Changing settings of MIDI input devices

   Use the following command to alter a specific setting of a created
   MIDI input device:

      SET MIDI_INPUT_DEVICE_PARAMETER <device-id> <key>=<value>

   Where <device-id> should be replaced by the numerical ID of the MIDI
   input device as returned by the "CREATE MIDI_INPUT_DEVICE"
   (Section 6.3.5) or "LIST MIDI_INPUT_DEVICES" (Section 6.3.8) command,
   <key> by the name of the parameter to change and <value> by the new
   value for this parameter.

   Possible Answers:

      "OK" -

         in case setting was successfully changed

      "WRN:<warning-code>:<warning-message>" -

         in case setting was changed successfully, but there are
         noteworthy issue(s) related, providing an appropriate warning
         code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:

      C: "SET MIDI_INPUT_DEVICE_PARAMETER 0 ACTIVE=false"

      S: "OK"

6.3.11.  Getting information about a MIDI port

   Use the following command to get information about a MIDI port:

      GET MIDI_INPUT_PORT INFO <device-id> <midi-port>

   Where <device-id> is the numerical ID of the MIDI input device as
   returned by the "CREATE MIDI_INPUT_DEVICE" (Section 6.3.5) or "LIST
   MIDI_INPUT_DEVICES" (Section 6.3.8) command and <midi-port> the MIDI
   input port number.

   Possible Answers:


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      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  At the moment the
      following information categories are defined:

      NAME -

         arbitrary character string naming the port

   The field above is only the one which is returned by all MIDI ports
   regardless of the MIDI driver and port.  Every MIDI port might have
   its own, additional driver and port specific parameters.

   Example:

      C: "GET MIDI_INPUT_PORT INFO 0 0"

      S: "NAME: 'Masterkeyboard'"

         "ALSA_SEQ_BINDINGS: '64:0'"

         "."

6.3.12.  Getting information about specific MIDI port parameter

   Use the following command to get detailed information about specific
   MIDI port parameter:

      GET MIDI_INPUT_PORT_PARAMETER INFO <dev-id> <port> <param>

   Where <dev-id> is the numerical ID of the MIDI input device as
   returned by the "CREATE MIDI_INPUT_DEVICE" (Section 6.3.5) or "LIST
   MIDI_INPUT_DEVICES" (Section 6.3.8) command, <port> the MIDI port
   number and <param> a specific port parameter name for which
   information should be obtained (as returned by the "GET
   MIDI_INPUT_PORT INFO" (Section 6.3.11) command).

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  There is information
      which is always returned, independently of the given channel
      parameter and there is optional information which are only shown
      dependently to the given MIDI port.  At the moment the following
      information categories are defined:


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      TYPE -

         either "BOOL" for boolean value(s) or "INT" for integer
         value(s) or "FLOAT" for dotted number(s) or "STRING" for
         character string(s) (always returned)

      DESCRIPTION -

         arbitrary text describing the purpose of the parameter (always
         returned)

      FIX -

         either true or false, if true then this parameter is read only,
         thus cannot be altered (always returned)

      MULTIPLICITY -

         either true or false, defines if this parameter allows only one
         value or a list of values, where true means multiple values and
         false only a single value allowed (always returned)

      RANGE_MIN -

         defines lower limit of the allowed value range for this
         parameter, can be an integer value as well as a dotted number,
         this parameter is usually used in conjunction with 'RANGE_MAX'
         but may also appear without (optionally returned, dependent to
         driver and port parameter)

      RANGE_MAX -

         defines upper limit of the allowed value range for this
         parameter, can be an integer value as well as a dotted number,
         this parameter is usually used in conjunction with 'RANGE_MIN'
         but may also appear without (optionally returned, dependent to
         driver and port parameter)

      POSSIBILITIES -

         comma separated list of possible values for this parameter,
         character strings are encapsulated into apostrophes (optionally
         returned, dependent to device and port parameter)

   The mentioned fields above don't have to be in particular order.

   Example:


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      C: "GET MIDI_INPUT_PORT_PARAMETER INFO 0 0 ALSA_SEQ_BINDINGS"

      S: "DESCRIPTION: bindings to other ALSA sequencer clients"

         "TYPE: STRING"

         "FIX: false"

         "MULTIPLICITY: true"

         "POSSIBILITIES: '64:0','68:0','68:1'"

         "."

6.3.13.  Changing settings of MIDI input ports

   Use the following command to alter a specific setting of a MIDI input
   port:

      SET MIDI_INPUT_PORT_PARAMETER <device-id> <port> <key>=<value>

   Where <device-id> should be replaced by the numerical ID of the MIDI
   device as returned by the "CREATE MIDI_INPUT_DEVICE" (Section 6.3.5)
   or "LIST MIDI_INPUT_DEVICES" (Section 6.3.8) command, <port> by the
   MIDI port number, <key> by the name of the parameter to change and
   <value> by the new value for this parameter.

   Possible Answers:

      "OK" -

         in case setting was successfully changed

      "WRN:<warning-code>:<warning-message>" -

         in case setting was changed successfully, but there are
         noteworthy issue(s) related, providing an appropriate warning
         code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


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6.4.  Configuring sampler channels

   The following commands describe how to add and remove sampler
   channels, associate a sampler channel with a sampler engine, load
   instruments and connect sampler channels to MIDI and audio devices.

6.4.1.  Loading an instrument

   An instrument file can be loaded and assigned to a sampler channel by
   one of the following commands:

      LOAD INSTRUMENT [NON_MODAL] '<filename>' <instr-index> <sampler-
      channel>

   Where <filename> is the name of the instrument file on the
   LinuxSampler instance's host system, <instr-index> the index of the
   instrument in the instrument file and <sampler-channel> is the number
   of the sampler channel the instrument should be assigned to.  Each
   sampler channel can only have one instrument.

   The difference between regular and NON_MODAL versions of the command
   is that the regular command returns OK only after the instrument has
   been fully loaded and the channel is ready to be used while NON_MODAL
   version returns immediately and a background process is launched to
   load the instrument on the channel.  The GET CHANNEL INFO
   (Section 6.4.10) command can be used to obtain loading progress from
   INSTRUMENT_STATUS field.  LOAD command will perform sanity checks
   such as making sure that the file could be read and it is of a proper
   format and SHOULD return ERR and SHOULD not launch the background
   process should any errors be detected at that point.

   Possible Answers:

      "OK" -

         in case the instrument was successfully loaded

      "WRN:<warning-code>:<warning-message>" -

         in case the instrument was loaded successfully, but there are
         noteworthy issue(s) related (e.g.  Engine doesn't support one
         or more patch parameters provided by the loaded instrument
         file), providing an appropriate warning code and warning
         message


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      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


6.4.2.  Loading a sampler engine

   A sampler engine type can be associated to a specific sampler channel
   by the following command:

      LOAD ENGINE <engine-name> <sampler-channel>

   Where <engine-name> is an engine name as obtained by the "LIST
   AVAILABLE_ENGINES" (Section 6.4.8) command and <sampler-channel> the
   sampler channel as returned by the "ADD CHANNEL" (Section 6.4.5) or
   "LIST CHANNELS" (Section 6.4.4) command where the engine type should
   be assigned to.  This command should be issued after adding a new
   sampler channel and before any other control commands on the new
   sampler channel.  It can also be used to change the engine type of a
   sampler channel.  This command has (currently) no way to define or
   force if a new engine instance should be created and assigned to the
   given sampler channel or if an already existing instance of that
   engine type, shared with other sampler channels, should be used.

   Possible Answers:

      "OK" -

         in case the engine was successfully deployed

      "WRN:<warning-code>:<warning-message>" -

         in case the engine was deployed successfully, but there are
         noteworthy issue(s) related, providing an appropriate warning
         code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


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6.4.3.  Getting all created sampler channel count

   The number of sampler channels can change on runtime.  To get the
   current amount of sampler channels, the front-end can send the
   following command:

      GET CHANNELS

   Possible Answers:

      LinuxSampler will answer by returning the current number of
      sampler channels.

   Example:

      C: "GET CHANNELS"

      S: "12"

6.4.4.  Getting all created sampler channel list

   The number of sampler channels can change on runtime.  To get the
   current list of sampler channels, the front-end can send the
   following command:

      LIST CHANNELS

   Possible Answers:

      LinuxSampler will answer by returning a comma separated list with
      all sampler channels numerical IDs.

   Example:

      C: "LIST CHANNELS"

      S: "0,1,2,3,4,5,6,9,10,11,15,20"

6.4.5.  Adding a new sampler channel

   A new sampler channel can be added to the end of the sampler channel
   list by sending the following command:

      ADD CHANNEL

   This will increment the sampler channel count by one and the new


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   sampler channel will be appended to the end of the sampler channel
   list.  The front-end should send the respective, related commands
   right after to e.g. load an engine, load an instrument and setting
   input, output method and eventually other commands to initialize the
   new channel.  The front-end should use the sampler channel returned
   by the answer of this command to perform the previously recommended
   commands, to avoid race conditions e.g. with other front-ends that
   might also have sent an "ADD CHANNEL" command.

   Possible Answers:

      "OK[<sampler-channel>]" -

         in case a new sampler channel could be added, where <sampler-
         channel> reflects the channel number of the new created sampler
         channel which should be used to set up the sampler channel by
         sending subsequent initialization commands

      "WRN:<warning-code>:<warning-message>" -

         in case a new channel was added successfully, but there are
         noteworthy issue(s) related, providing an appropriate warning
         code and warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


6.4.6.  Removing a sampler channel

   A sampler channel can be removed by sending the following command:

      REMOVE CHANNEL <sampler-channel>

   Where <sampler-channel> should be replaced by the number of the
   sampler channel as given by the "ADD CHANNEL" (Section 6.4.5) or
   "LIST CHANNELS" (Section 6.4.4) command.  The channel numbers of all
   subsequent sampler channels remain the same.

   Possible Answers:


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      "OK" -

         in case the given sampler channel could be removed

      "WRN:<warning-code>:<warning-message>" -

         in case the given channel was removed, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Example:


6.4.7.  Getting amount of available engines

   The front-end can ask for the number of available engines by sending
   the following command:

      GET AVAILABLE_ENGINES

   Possible Answers:

      LinuxSampler will answer by sending the number of available
      engines.

   Example:

      C: "GET AVAILABLE_ENGINES"

      S: "4"

6.4.8.  Getting all available engines

   The front-end can ask for a list of all available engines by sending
   the following command:

      LIST AVAILABLE_ENGINES

   Possible Answers:


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      LinuxSampler will answer by sending a comma separated list of the
      engines' names encapsulated into apostrophes (').  Engine names
      can consist of lower and upper cases, digits and underlines ("_"
      character).

   Example:

      C: "LIST AVAILABLE_ENGINES"

      S: "'GigEngine','AkaiEngine','DLSEngine','JoesCustomEngine'"

6.4.9.  Getting information about an engine

   The front-end can ask for information about a specific engine by
   sending the following command:

      GET ENGINE INFO <engine-name>

   Where <engine-name> is an engine name as obtained by the "LIST
   AVAILABLE_ENGINES" (Section 6.4.8) command.

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info
      character string to that info category.  At the moment the
      following categories are defined:


         DESCRIPTION -

            arbitrary description text about the engine

         VERSION -

            arbitrary character string regarding the engine's version

   The mentioned fields above don't have to be in particular order.

   Example:

      C: "GET ENGINE INFO JoesCustomEngine"

      S: "DESCRIPTION: this is Joe's custom sampler engine"


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         "VERSION: testing-1.0"

         "."

6.4.10.  Getting sampler channel information

   The front-end can ask for the current settings of a sampler channel
   by sending the following command:

      GET CHANNEL INFO <sampler-channel>

   Where <sampler-channel> is the sampler channel number the front-end
   is interested in as returned by the "ADD CHANNEL" (Section 6.4.5) or
   "LIST CHANNELS" (Section 6.4.4) command.

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the settings category name followed by a
      colon and then a space character <SP> and finally the info
      character string to that setting category.  At the moment the
      following categories are defined:


         ENGINE_NAME -

            name of the engine that is associated with the sampler
            channel, "NONE" if there's no engine associated yet for this
            sampler channel

         AUDIO_OUTPUT_DEVICE -

            numerical ID of the audio output device which is currently
            connected to this sampler channel to output the audio
            signal, "NONE" if there's no device connected to this
            sampler channel

         AUDIO_OUTPUT_CHANNELS -

            number of output channels the sampler channel offers
            (dependent to used sampler engine and loaded instrument)

         AUDIO_OUTPUT_ROUTING -

            comma separated list which reflects to which audio channel
            of the selected audio output device each sampler output
            channel is routed to, e.g. "0,3" would mean the engine's


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            output channel 0 is routed to channel 0 of the audio output
            device and the engine's output channel 1 is routed to the
            channel 3 of the audio output device

         INSTRUMENT_FILE -

            the file name of the loaded instrument, "NONE" if there's no
            instrument yet loaded for this sampler channel

         INSTRUMENT_NR -

            the instrument index number of the loaded instrument

         INSTRUMENT_NAME -

            the instrument name of the loaded instrument

         INSTRUMENT_STATUS -

            integer values 0 to 100 indicating loading progress
            percentage for the instrument.  Negative value indicates a
            loading exception.  Value of 100 indicates that the
            instrument is fully loaded.

         MIDI_INPUT_DEVICE -

            numerical ID of the MIDI input device which is currently
            connected to this sampler channel to deliver MIDI input
            commands, "NONE" if there's no device connected to this
            sampler channel

         MIDI_INPUT_PORT -

            port number of the MIDI input device

         MIDI_INPUT_CHANNEL -

            the MIDI input channel number this sampler channel should
            listen to or "ALL" to listen on all MIDI channels

         VOLUME -

            optionally dotted number for the channel volume factor
            (where a value < 1.0 means attenuation and a value > 1.0
            means amplification)


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         MUTE -

            Determines whether the channel is muted, "true" if the
            channel is muted, "false" if the channel is not muted, and
            "MUTED_BY_SOLO" if the channel is muted because of the
            presence of a solo channel and will be unmuted when there
            are no solo channels left

         SOLO -

            Determines whether this is a solo channel, "true" if the
            channel is a solo channel; "false" otherwise

   The mentioned fields above don't have to be in particular order.

   Example:

      C: "GET CHANNEL INFO 34"

      S: "ENGINE_NAME: GigEngine"

         "VOLUME: 1.0"

         "AUDIO_OUTPUT_DEVICE: 0"

         "AUDIO_OUTPUT_CHANNELS: 2"

         "AUDIO_OUTPUT_ROUTING: 0,1"

         "INSTRUMENT_FILE: /home/joe/FazioliPiano.gig"

         "INSTRUMENT_NR: 0"

         "INSTRUMENT_NAME: Fazioli Piano"

         "INSTRUMENT_STATUS: 100"

         "MIDI_INPUT_DEVICE: 0"

         "MIDI_INPUT_PORT: 0"

         "MIDI_INPUT_CHANNEL: 5"

         "."


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6.4.11.  Current number of active voices

   The front-end can ask for the current number of active voices on a
   sampler channel by sending the following command:

      GET CHANNEL VOICE_COUNT <sampler-channel>

   Where <sampler-channel> is the sampler channel number the front-end
   is interested in as returned by the "ADD CHANNEL" (Section 6.4.5) or
   "LIST CHANNELS" (Section 6.4.4) command.

   Possible Answers:

      LinuxSampler will answer by returning the number of active voices
      on that channel.

   Example:


6.4.12.  Current number of active disk streams

   The front-end can ask for the current number of active disk streams
   on a sampler channel by sending the following command:

      GET CHANNEL STREAM_COUNT <sampler-channel>

   Where <sampler-channel> is the sampler channel number the front-end
   is interested in as returned by the "ADD CHANNEL" (Section 6.4.5) or
   "LIST CHANNELS" (Section 6.4.4) command.

   Possible Answers:

      LinuxSampler will answer by returning the number of active disk
      streams on that channel in case the engine supports disk
      streaming, if the engine doesn't support disk streaming it will
      return "NA" for not available.

   Example:


6.4.13.  Current fill state of disk stream buffers

   The front-end can ask for the current fill state of all disk streams
   on a sampler channel by sending the following command:


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      GET CHANNEL BUFFER_FILL BYTES <sampler-channel>

   to get the fill state in bytes or

      GET CHANNEL BUFFER_FILL PERCENTAGE <sampler-channel>

   to get the fill state in percent, where <sampler-channel> is the
   sampler channel number the front-end is interested in as returned by
   the "ADD CHANNEL" (Section 6.4.5) or "LIST CHANNELS" (Section 6.4.4)
   command.

   Possible Answers:

      LinuxSampler will either answer by returning a comma separated
      string with the fill state of all disk stream buffers on that
      channel or an empty line if there are no active disk streams or
      "NA" for *not available* in case the engine which is deployed
      doesn't support disk streaming.  Each entry in the answer list
      will begin with the stream's ID in brackets followed by the
      numerical representation of the fill size (either in bytes or
      percentage).  Note: due to efficiency reasons the fill states in
      the response are not in particular order, thus the front-end has
      to sort them by itself if necessary.

   Examples:

      C: "GET CHANNEL BUFFER_FILL BYTES 4"

      S: "[115]420500,[116]510300,[75]110000,[120]230700"

      C: "GET CHANNEL BUFFER_FILL PERCENTAGE 4"

      S: "[115]90%,[116]98%,[75]40%,[120]62%"

      C: "GET CHANNEL BUFFER_FILL PERCENTAGE 4"

      S: ""

6.4.14.  Setting audio output device

   The front-end can set the audio output device on a specific sampler
   channel by sending the following command:

      SET CHANNEL AUDIO_OUTPUT_DEVICE <sampler-channel>
      <audio-device-id>

   Where <sampler-channel> is the respective sampler channel number as
   returned by the "ADD CHANNEL" (Section 6.4.5) or "LIST CHANNELS"


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   (Section 6.4.4) command and <audio-device-id> is the numerical ID of
   the audio output device as given by the "CREATE AUDIO_OUTPUT_DEVICE"
   (Section 6.2.5) or "LIST AUDIO_OUTPUT_DEVICES" (Section 6.2.8)
   command.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if audio output device was set, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.15.  Setting audio output type

   DEPRECATED: THIS COMMAND WILL DISAPPEAR SOON!

   The front-end can alter the audio output type on a specific sampler
   channel by sending the following command:

      SET CHANNEL AUDIO_OUTPUT_TYPE <sampler-channel> <audio-output-
      type>

   Where <audio-output-type> is currently either "ALSA" or "JACK" and
   <sampler-channel> is the respective sampler channel number.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -


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         if audio output type was set, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.16.  Setting audio output channel

   The front-end can alter the audio output channel on a specific
   sampler channel by sending the following command:

      SET CHANNEL AUDIO_OUTPUT_CHANNEL <sampler-chan> <audio-out>
      <audio-in>

   Where <sampler-chan> is the sampler channel number as returned by the
   "ADD CHANNEL" (Section 6.4.5) or "LIST CHANNELS" (Section 6.4.4)
   command, <audio-out> is the numerical ID of the sampler channel's
   audio output channel which should be rerouted and <audio-in> is the
   numerical ID of the audio channel of the selected audio output device
   where <audio-out> should be routed to.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if audio output channel was set, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


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6.4.17.  Setting MIDI input device

   The front-end can set the MIDI input device on a specific sampler
   channel by sending the following command:

      SET CHANNEL MIDI_INPUT_DEVICE <sampler-channel> <midi-device-id>

   Where <sampler-channel> is the sampler channel number as returned by
   the "ADD CHANNEL" (Section 6.4.5) or "LIST CHANNELS" (Section 6.4.4)
   command and <midi-device-id> is the numerical ID of the MIDI input
   device as returned by the "CREATE MIDI_INPUT_DEVICE" (Section 6.3.5)
   or "LIST MIDI_INPUT_DEVICES" (Section 6.3.8) command.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if MIDI input device was set, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.18.  Setting MIDI input type

   DEPRECATED: THIS COMMAND WILL DISAPPEAR SOON!

   The front-end can alter the MIDI input type on a specific sampler
   channel by sending the following command:

      SET CHANNEL MIDI_INPUT_TYPE <sampler-channel> <midi-input-type>

   Where <midi-input-type> is currently only "ALSA" and <sampler-
   channel> is the respective sampler channel number.


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   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if MIDI input type was set, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.19.  Setting MIDI input port

   The front-end can alter the MIDI input port on a specific sampler
   channel by sending the following command:

      SET CHANNEL MIDI_INPUT_PORT <sampler-channel> <midi-input-port>

   Where <midi-input-port> is a MIDI input port number of the MIDI input
   device connected to the sampler channel given by <sampler-channel>.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if MIDI input port was set, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message


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   Examples:


6.4.20.  Setting MIDI input channel

   The front-end can alter the MIDI channel a sampler channel should
   listen to by sending the following command:

      SET CHANNEL MIDI_INPUT_CHANNEL <sampler-channel> <midi-input-chan>

   Where <midi-input-chan> is the number of the new MIDI input channel
   where <sampler-channel> should listen to or "ALL" to listen on all 16
   MIDI channels.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if MIDI input channel was set, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.21.  Setting channel volume

   The front-end can alter the volume of a sampler channel by sending
   the following command:

      SET CHANNEL VOLUME <sampler-channel> <volume>

   Where <volume> is an optionally dotted positive number (a value
   smaller than 1.0 means attenuation, whereas a value greater than 1.0
   means amplification) and <sampler-channel> defines the sampler
   channel where this volume factor should be set.


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   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if channel volume was set, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.22.  Muting a sampler channel

   The front-end can mute/unmute a specific sampler channel by sending
   the following command:

      SET CHANNEL MUTE <sampler-channel> <mute>

   Where <sampler-channel> is the respective sampler channel number as
   returned by the "ADD CHANNEL" (Section 6.4.5) or "LIST CHANNELS"
   (Section 6.4.4) command and <mute> should be replaced either by "1"
   to mute the channel or "0" to unmute the channel.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if the channel was muted/unmuted, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -


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         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.23.  Soloing a sampler channel

   The front-end can solo/unsolo a specific sampler channel by sending
   the following command:

      SET CHANNEL SOLO <sampler-channel> <solo>

   Where <sampler-channel> is the respective sampler channel number as
   returned by the "ADD CHANNEL" (Section 6.4.5) or "LIST CHANNELS"
   (Section 6.4.4) command and <solo> should be replaced either by "1"
   to solo the channel or "0" to unsolo the channel.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if the channel was soloed/unsoloed, but there are noteworthy
         issue(s) related, providing an appropriate warning code and
         warning message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.4.24.  Resetting a sampler channel

   The front-end can reset a particular sampler channel by sending the
   following command:

      RESET CHANNEL <sampler-channel>

   Where <sampler-channel> defines the sampler channel to be reset.


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   This will cause the engine on that sampler channel, its voices and
   eventually disk streams and all control and status variables to be
   reset.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if channel was reset, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.5.  Controlling connection

   The following commands are used to control the connection to
   LinuxSampler.

6.5.1.  Register front-end for receiving event messages

   The front-end can register itself to the LinuxSampler application to
   be informed about noteworthy events by sending this command:

      SUBSCRIBE <event-id>

   where <event-id> will be replaced by the respective event that client
   wants to subscribe to.

   Possible Answers:

      "OK" -

         on success


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      "WRN:<warning-code>:<warning-message>" -

         if registration succeeded, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


6.5.2.  Unregister front-end for not receiving event messages

   The front-end can unregister itself if it doesn't want to receive
   event messages anymore by sending the following command:

      UNSUBSCRIBE <event-id>

   Where <event-id> will be replaced by the respective event that client
   doesn't want to receive anymore.

   Possible Answers:

      "OK" -

         on success

      "WRN:<warning-code>:<warning-message>" -

         if unregistration succeeded, but there are noteworthy issue(s)
         related, providing an appropriate warning code and warning
         message

      "ERR:<error-code>:<error-message>" -

         in case it failed, providing an appropriate error code and
         error message

   Examples:


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6.5.3.  Enable or disable echo of commands

   To enable or disable back sending of commands to the client the
   following command can be used:

      SET ECHO <value>

   Where <value> should be replaced either by "1" to enable echo mode or
   "0" to disable echo mode.  When echo mode is enabled, all commands
   send to LinuxSampler will be immediately send back and after this
   echo the actual response to the command will be returned.  Echo mode
   will only be altered for the client connection that issued the "SET
   ECHO" command, not globally for all client connections.

   Possible Answers:

      "OK" -

         usually

      "ERR:<error-code>:<error-message>" -

         on syntax error, e.g. non boolean value

   Examples:


6.5.4.  Close client connection

   The client can close its network connection to LinuxSampler by
   sending the following command:

      QUIT

   This is probably more interesting for manual telnet connections to
   LinuxSampler than really useful for a front-end implementation.

6.6.  Global commands

   The following commands have global impact on the sampler.

6.6.1.  Current number of active voices

   The front-end can ask for the current number of active voices on the
   sampler by sending the following command:


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      GET TOTAL_VOICE_COUNT

   Possible Answers:

      LinuxSampler will answer by returning the number of all active
      voices on the sampler.

6.6.2.  Maximum amount of active voices

   The front-end can ask for the maximum number of active voices by
   sending the following command:

      GET TOTAL_VOICE_COUNT_MAX

   Possible Answers:

      LinuxSampler will answer by returning the maximum number of active
      voices.

6.6.3.  Reset sampler

   The front-end can reset the whole sampler by sending the following
   command:

      RESET

   Possible Answers:

      "OK" -

         always

   Examples:


6.6.4.  General sampler informations

   The client can ask for general informations about the LinuxSampler
   instance by sending the following command:

      GET SERVER INFO

   Possible Answers:

      LinuxSampler will answer by sending a <CRLF> separated list.  Each
      answer line begins with the information category name followed by
      a colon and then a space character <SP> and finally the info


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      character string to that information category.  At the moment the
      following categories are defined:


         DESCRIPTION -

            arbitrary textual description about the sampler

         VERSION -

            version of the sampler

         PROTOCOL_VERSION -

            version of the LSCP specification the sampler complies with
            (see Section 2 for details)

   The mentioned fields above don't have to be in particular order.
   Other fields might be added in future.


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7.  Command Syntax

   The grammar of the control protocol as descibed in Section 6 is
   defined below using Backus-Naur Form (BNF as described in [RFC2234])
   where applicable.

   input =

      line LF

      / line CR LF

   line =

      /* epsilon (empty line ignored) */

      / comment

      / command

      / error

   comment =

      '#'

      / comment '#'

      / comment SP

      / comment number

      / comment string

   command =

      ADD SP CHANNEL

      / GET SP get_instruction

      / CREATE SP create_instruction

      / DESTROY SP destroy_instruction

      / LIST SP list_instruction

      / LOAD SP load_instruction


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      / REMOVE SP CHANNEL SP sampler_channel

      / SET SP set_instruction

      / SUBSCRIBE SP subscribe_event

      / UNSUBSCRIBE SP unsubscribe_event

      / SELECT SP text

      / RESET SP CHANNEL SP sampler_channel

      / RESET

      / QUIT

   subscribe_event =

      CHANNEL_COUNT

      / VOICE_COUNT

      / STREAM_COUNT

      / BUFFER_FILL

      / CHANNEL_INFO

      / MISCELLANEOUS

      / TOTAL_VOICE_COUNT

   unsubscribe_event =

      CHANNEL_COUNT

      / VOICE_COUNT

      / STREAM_COUNT

      / BUFFER_FILL

      / CHANNEL_INFO

      / MISCELLANEOUS

      / TOTAL_VOICE_COUNT


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   get_instruction =

      AVAILABLE_ENGINES

      / AVAILABLE_MIDI_INPUT_DRIVERS

      / MIDI_INPUT_DRIVER SP INFO SP string

      / MIDI_INPUT_DRIVER_PARAMETER SP INFO SP string SP string

      / MIDI_INPUT_DRIVER_PARAMETER SP INFO SP string SP string SP
      key_val_list

      / AVAILABLE_AUDIO_OUTPUT_DRIVERS

      / AUDIO_OUTPUT_DRIVER SP INFO SP string

      / AUDIO_OUTPUT_DRIVER_PARAMETER SP INFO SP string SP string

      / AUDIO_OUTPUT_DRIVER_PARAMETER SP INFO SP string SP string SP
      key_val_list

      / AUDIO_OUTPUT_DEVICES

      / MIDI_INPUT_DEVICES

      / AUDIO_OUTPUT_DEVICE SP INFO SP number

      / MIDI_INPUT_DEVICE SP INFO SP number

      / MIDI_INPUT_PORT SP INFO SP number SP number

      / MIDI_INPUT_PORT_PARAMETER SP INFO SP number SP number SP string

      / AUDIO_OUTPUT_CHANNEL SP INFO SP number SP number

      / AUDIO_OUTPUT_CHANNEL_PARAMETER SP INFO SP number SP number SP
      string

      / CHANNELS

      / CHANNEL SP INFO SP sampler_channel

      / CHANNEL SP BUFFER_FILL SP buffer_size_type SP sampler_channel

      / CHANNEL SP STREAM_COUNT SP sampler_channel


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      / CHANNEL SP VOICE_COUNT SP sampler_channel

      / ENGINE SP INFO SP engine_name

      / SERVER SP INFO

      / TOTAL_VOICE_COUNT

      / TOTAL_VOICE_COUNT_MAX

   set_instruction =

      AUDIO_OUTPUT_DEVICE_PARAMETER SP number SP string '='
      param_val_list

      / AUDIO_OUTPUT_CHANNEL_PARAMETER SP number SP number SP string '='
      param_val_list

      / MIDI_INPUT_DEVICE_PARAMETER SP number SP string '='
      param_val_list

      / MIDI_INPUT_PORT_PARAMETER SP number SP number SP string '='
      param_val_list

      / CHANNEL SP set_chan_instruction

      / ECHO SP boolean

   create_instruction =

      AUDIO_OUTPUT_DEVICE SP string SP key_val_list

      / AUDIO_OUTPUT_DEVICE SP string

      / MIDI_INPUT_DEVICE SP string SP key_val_list

      / MIDI_INPUT_DEVICE SP string

   destroy_instruction =

      AUDIO_OUTPUT_DEVICE SP number

      / MIDI_INPUT_DEVICE SP number

   load_instruction =

      INSTRUMENT SP load_instr_args


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      / ENGINE SP load_engine_args

   set_chan_instruction =

      AUDIO_OUTPUT_DEVICE SP sampler_channel SP device_index

      / AUDIO_OUTPUT_CHANNEL SP sampler_channel SP audio_channel_index
      SP audio_channel_index

      / AUDIO_OUTPUT_TYPE SP sampler_channel SP audio_output_type_name

      / MIDI_INPUT SP sampler_channel SP device_index SP
      midi_input_port_index SP midi_input_channel_index

      / MIDI_INPUT_DEVICE SP sampler_channel SP device_index

      / MIDI_INPUT_PORT SP sampler_channel SP midi_input_port_index

      / MIDI_INPUT_CHANNEL SP sampler_channel SP
      midi_input_channel_index

      / MIDI_INPUT_TYPE SP sampler_channel SP midi_input_type_name

      / VOLUME SP sampler_channel SP volume_value

      / MUTE SP sampler_channel SP boolean

      / SOLO SP sampler_channel SP boolean

   key_val_list =

      string '=' param_val_list

      / key_val_list SP string '=' param_val_list

   buffer_size_type =

      BYTES

      / PERCENTAGE

   list_instruction =

      AUDIO_OUTPUT_DEVICES

      / MIDI_INPUT_DEVICES


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      / CHANNELS

      / AVAILABLE_ENGINES

      / AVAILABLE_MIDI_INPUT_DRIVERS

      / AVAILABLE_AUDIO_OUTPUT_DRIVERS

   load_instr_args =

      filename SP instrument_index SP sampler_channel

      / NON_MODAL SP filename SP instrument_index SP sampler_channel

   load_engine_args =

      engine_name SP sampler_channel

   device_index =

      number

   audio_channel_index =

      number

   audio_output_type_name =

      string

   midi_input_port_index =

      number

   midi_input_channel_index =

      number

      / ALL

   midi_input_type_name =

      string

   volume_value =

      dotnum


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      / number

   sampler_channel =

      number

   instrument_index =

      number

   engine_name =

      string

   filename =

      stringval

   param_val_list =

      param_val

      / param_val_list','param_val

   param_val =

      string

      / stringval

      / number

      / dotnum


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8.  Events

   This chapter will describe all currently defined events supported by
   LinuxSampler.

8.1.  Number of sampler channels changed

   Client may want to be notified when the total number of channels on
   the back-end changes by issuing the following command:

      SUBSCRIBE CHANNEL_COUNT

   Server will start sending the following notification messages:

      "NOTIFY:CHANNEL_COUNT:<channels>"

   where <channels> will be replaced by the new number of sampler
   channels.

8.2.  Number of active voices changed

   Client may want to be notified when the number of voices on the back-
   end changes by issuing the following command:

      SUBSCRIBE VOICE_COUNT

   Server will start sending the following notification messages:

      "NOTIFY:VOICE_COUNT:<sampler-channel> <voices>

   where <sampler-channel> will be replaced by the sampler channel the
   voice count change occurred and <voices> by the new number of active
   voices on that channel.

8.3.  Number of active disk streams changed

   Client may want to be notified when the number of streams on the
   back-end changes by issuing the following command: SUBSCRIBE
   STREAM_COUNT

      SUBSCRIBE STREAM_COUNT

   Server will start sending the following notification messages:

      "NOTIFY:STREAM_COUNT:<sampler-channel> <streams>"

   where <sampler-channel> will be replaced by the sampler channel the
   stream count change occurred and <streams> by the new number of


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   active disk streams on that channel.

8.4.  Disk stream buffer fill state changed

   Client may want to be notified when the buffer fill state of a disk
   stream on the back-end changes by issuing the following command:

      SUBSCRIBE BUFFER_FILL

   Server will start sending the following notification messages:

      "NOTIFY:BUFFER_FILL:<sampler-channel> <fill-data>"

   where <sampler-channel> will be replaced by the sampler channel the
   buffer fill state change occurred on and <fill-data> will be replaced
   by the buffer fill data for this channel as described in
   Section 6.4.13 as if the "GET CHANNEL BUFFER_FILL PERCENTAGE"
   (Section 6.4.13) command was issued on this channel.

8.5.  Channel information changed

   Client may want to be notified when changes were made to sampler
   channels on the back-end by issuing the following command:

      SUBSCRIBE CHANNEL_INFO

   Server will start sending the following notification messages:

      "NOTIFY:CHANNEL_INFO:<sampler-channel>"

   where <sampler-channel> will be replaced by the sampler channel the
   channel info change occurred.  The front-end will have to send the
   respective command to actually get the channel info.  Because these
   messages will be triggered by LSCP commands issued by other clients
   rather than real time events happening on the server, it is believed
   that an empty notification message is sufficient here.

8.6.  Total number of active voices changed

   Client may want to be notified when the total number of voices on the
   back-end changes by issuing the following command:

      SUBSCRIBE TOTAL_VOICE_COUNT

   Server will start sending the following notification messages:


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      "NOTIFY:TOTAL_VOICE_COUNT:<voices>

   where <voices> will be replaced by the new number of all currently
   active voices.

8.7.  Miscellaneous and debugging events

   Client may want to be notified of miscellaneous and debugging events
   occurring at the server by issuing the following command:

      SUBSCRIBE MISCELLANEOUS

   Server will start sending the following notification messages:

      "NOTIFY:MISCELLANEOUS:<string>"

   where <string> will be replaced by whatever data server wants to send
   to the client.  Client MAY display this data to the user AS IS to
   facilitate debugging.


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9.  Security Considerations

   As there is so far no method of authentication and authorization
   defined and so not required for a client applications to succeed to
   connect, running LinuxSampler might be a security risk for the host
   system the LinuxSampler instance is running on.


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10.  Acknowledgments

   This document has benefited greatly from the comments of the
   following people, discussed on the LinuxSampler developer's mailing
   list:

      Rui Nuno Capela

      Vladimir Senkov

      Mark Knecht

      Grigor Iliev


11.  References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, 1997.

   [RFC2234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications", RFC 2234, 1997.

   [RFC793]   Defense Advanced Research Projects Agency, "TRANSMISSION
              CONTROL PROTOCOL", RFC 793, 1981.


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Author's Address

   C. Schoenebeck
   Interessengemeinschaft Software Engineering e. V.
   Max-Planck-Str. 39
   74081 Heilbronn
   Germany

   Email: schoenebeck at software minus engineering dot org


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Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP 11.  Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

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Acknowledgment

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