path: root/arts/midi/artsmidi.idl

	/*

    Copyright (C) 2000 Stefan Westerfeld
                       stefan@space.twc.de

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.
  
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.
   
    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.

    */

/*
 * DISCLAIMER: The interfaces in artsmidi.idl (and the derived .cpp/.h files)
 *             DO NOT GUARANTEE BINARY COMPATIBILITY YET.
 *
 * They are intended for developers. You shouldn't expect that applications in
 * binary form will be fully compatibile with further releases of these
 * interfaces.
 */

#include <artsflow.idl>

module Arts {

/* This is modelled somewhat after
    - the AudioManager concept
	- the aRts-0.3.4.1 MidiPort concept
	- libtdemid

   It adds timing as new feature compared to older implementation, and also
   tries to do the full set of midi operations.

   It's current state is "experimental", and "binary compatibility not kept".
 */

/**
 * an absolute timestamp
 */
struct TimeStamp {
	long sec,usec;
};

/**
 * different status of a midi command
 */
enum MidiCommandStatus {
// Masks:
	mcsCommandMask		= 0xf0,
	mcsChannelMask		= 0x0f,

// Commands:
	mcsNoteOff			= 0x80,
	mcsNoteOn			= 0x90,
	mcsKeyPressure		= 0xa0,
	mcsParameter		= 0xb0,
	mcsProgram			= 0xc0,
	mcsChannelPressure	= 0xd0,
	mcsPitchWheel		= 0xe0
};

/**
 * the following are to be used once status is (mcsParameter|channel):
 */
enum MidiCommandParameter {
	mcpSustain			= 0x40,
	mcpAllNotesOff		= 0x7b
};

/**
 * a midi command
 */
struct MidiCommand {
	byte status;
	byte data1;
	byte data2;
};

/**
 * a midi event
 */

struct MidiEvent {
	TimeStamp time;
	MidiCommand command;
};

/**
 * a midi port
 */
interface MidiPort {
	/**
	 * the current absolute time (since the existence of the midi device)
	 */
	readonly attribute TimeStamp time;

	/**
	 * the current play time 
	 *
	 * Some midi devices, for instance synthetic audio devices, have a certain
	 * amount of internal buffering. This causes a time difference between
	 * where events are currently being rendered, which is the timestamp
	 * obtained by "time", and the events that the listener is hearing right
	 * now, which is this timestamp, the "playTime".
	 */
	readonly attribute TimeStamp playTime;

	/**
	 * processes a midi command
	 */
	oneway void processCommand(MidiCommand command);

	/**
	 * processes a midi event
	 */
	oneway void processEvent(MidiEvent event);
};

enum MidiClientDirection { mcdPlay, mcdRecord }; 
enum MidiClientType { mctDestination, mctApplication }; 

/**
 * information about a midi client
 */
struct MidiClientInfo {
	long ID;
	sequence<long> connections;

	MidiClientDirection direction;
	MidiClientType type;
	string title, autoRestoreID;
};

/**
 * a midi manager client
 */
interface MidiClient {
    readonly attribute MidiClientInfo info;

	/**
	 * you can change the title of your client on the fly - everything else
	 * (besides the actual assignment) is static
	 */
    attribute string title;
 
	/**
	 * creates a new port through which the client can receive data from
	 * the midi manager
	 */
	void addInputPort(MidiPort port);

	/**
	 * creates a new port through which the client can send data to the
	 * midi manager
	 */
	MidiPort addOutputPort();

	/**
	 * removes a port
	 */
	void removePort(MidiPort port);
};

interface AudioSync;

/**
 * this synchronizes multiple midi clients - it also allows synchronization
 * with audio events
 */
interface MidiSyncGroup {
	/**
	 * adds a midi client to the synchronization group
	 *
	 * hint: during adding the client, the timestamps related to that
	 * client will jump
	 */
	void addClient(MidiClient client);

	/**
	 * deletes a midi client from the synchronization group
	 */
	void removeClient(MidiClient client);

	/**
	 * adds an AudioSync object to the synchronization group
	 *
	 * hint: during adding the AudioSync object, the timestamps related to
	 * that object might jump
	 */
	void addAudioSync(AudioSync audioSync);

	/**
	 * deletes an AudioSync object from the synchronization group
	 */
	void removeAudioSync(AudioSync audioSync);
};

/**
 * Some general notes to the understanding of the midi manager. The midi
 * manager has the task to intelligently assign applications to destinations.
 *
 * It is important to understand what it actually does to understand the
 * distinction first, which is expressed through the "MidiClientType" of
 * each client.
 *
 * APPLICATIONS: An application is a user visible application, that produces
 *    or records midi data. It is important for the understanding of an
 *    application, that an application actually *wants* to be supplied with
 *    data, or wants to get its data played. Thus, adding an application to
 *    the midi manager is an implicit request: "go and find a place where to
 *    put the events to (or get the events from)".
 *
 *    Examples for applications would be games or midi players.
 *
 * DESTINATIONS: A destination is a system service that plays or supplies
 *    midi data. The characteristic here is that a destination is something
 *    that is there if you need it.
 *
 *    Examples for destinations might be might be a hardware device or an
 *    emulation of a hardware device (such as a virtual sampler).
 *
 * So the process is as follows:
 *  - destinations register themselves at the midi manager, and provide
 *    system services in that way
 *
 *  - when the user starts an application (such as a midi player), the midi
 *    manager's task is to assign it to a suitable destination
 *
 *  - the user can interact with the process by changing the way applications
 *    are assigned to destinations - the midi manager will try to learn
 *    what the user wants, and next time do a better job while assigning
 *
 * To actually record or play some data, you need to register a client first,
 * and after that, you can add Input or Output "MidiPort"s to your client,
 * so that you can actually send or receive events with them.
 */
interface MidiManager { // SINGLETON: Arts_MidiManager
    /**
     * a list of clients
     */
    readonly attribute sequence<MidiClientInfo> clients;

	/**
	 * add a client
     *
	 * this creates a new MidiManagerClient
	 */ 
	MidiClient addClient(MidiClientDirection direction, MidiClientType type,
							string title, string autoRestoreID);

	/**
	 * connect two clients
	 */
	void connect(long clientID, long destinationID);

	/**
	 * disconnect two clients
	 */
	void disconnect(long clientID, long destinationID);

	/**
	 * add a synchronization group
	 *
	 * this creates a new MidiSyncGroup
	 */
	MidiSyncGroup addSyncGroup();
};                                                                              

interface MidiTest : MidiPort {
};

interface RawMidiPort : MidiPort {
	attribute string device;
	attribute boolean input, output;
	attribute boolean running;
	boolean open();
};

interface AlsaMidiGateway {
	boolean rescan();
};

interface AlsaMidiPort : MidiPort {
	attribute long client;
	attribute long port;
	boolean open();
};

/**
 * EXPERIMENTAL interface for audio synchronization - this allows multiple
 * objects to be started and stopped at a precisely defined timestamp
 */
interface AudioSync {
	/**
	 * the current time
	 */
	readonly attribute TimeStamp time;

	/**
	 * the current play time 
	 *
	 * Since aRts has internal buffering, there is a time difference between
	 * where events are currently being rendered, which is the timestamp
	 * obtained by "time", and the events that the listener is hearing right
	 * now, which is this timestamp, the "playTime".
	 */
	readonly attribute TimeStamp playTime;

    /**
     * queues calling synthModule.start() later
     *
     * (will keep a reference on the module until executed)
     */
    void queueStart(SynthModule synthModule);

    /**
     * queues calling synthModule.stop() later
     *
     * (will keep a reference on the module until executed)
     */
    void queueStop(SynthModule synthModule);

    /**
     * atomically executes all queued modification to the flow system
     */
    void execute();

	/**
	 * atomically executes all queued modifications to the flow system
	 * at a given time
	 */
	void executeAt(TimeStamp timeStamp);
};

/**
 * Midi Timer - can be used to provide timing for midi ports that have
 * no "native" timing.
 */
interface MidiTimer
{
	/**
	 * the current time
	 */
	readonly attribute TimeStamp time;

	/**
	 * this will put the event into an event queue and send it to the port
	 * once the time for the event has been reached
	 */
	oneway void queueEvent(MidiPort port, MidiEvent event);
};

/**
 * Uses the system time (i.e. gettimeofday() and similar) to provide midi
 * timing
 */
interface SystemMidiTimer : MidiTimer
{
};

/**
 * Uses the audio time (i.e. samples rendered to /dev/dsp) to provide midi
 * timing
 */
interface AudioMidiTimer : MidiTimer
{
};

};