MIDI Services Reference

Framework
CoreMIDI.framework
Declared in
MIDIServices.h

Overview

MIDI drivers own and control MIDI devices, which include such things as USB interfaces, MIDI keyboards, and so on. A device is defined as a physical object that would be represented by a single icon if there were a graphical view of the studio.

A MIDI device may have multiple logically distinct sub-components. For example, one device may encompass a MIDI synthesizer and a pair of MIDI ports, both addressable via a USB port. Each such element of a device is called a MIDI entity.

A MIDI entity can have any number of MIDI endpoints, each of which is a source or destination of a 16-channel MIDI stream. By grouping a device’s endpoints into entities, the system has enough information for an application to make reasonable default assumptions about how to communicate in a bi-directional manner with each entity, as is necessary in MIDI librarian applications.

Core MIDI attaches a collection of properties to each object it manages. Some properties are dynamic characteristics of a device—such as MIDI receive channel and system-exclusive IDs. Other properties are a matter of user preference—such as choice of icon, and whether or not the device should appear in lists of possible controllers. Still other properties are static and could be looked up in a database, using the device’s manufacturer and model names as a key.

The Core MIDI framework uses IPC (interprocess communication) to communicate with a server process, the MIDI server. The server process in turn loads, and manages all communication with, the MIDI driver.

Functions by Task

Using MIDI Ports

Using MIDI Packet Lists

Using MIDI Objects and Properties

Using MIDI I/O

Using MIDI External Devices

Using MIDI Entities

Using MIDI Endpoints

Using MIDI Devices

Using MIDI Clients

Functions

MIDIClientCreate

Creates a MIDIClient object.

OSStatus MIDIClientCreate (
   CFStringRef     name,
   MIDINotifyProc  notifyProc,
   void            *notifyRefCon,
   MIDIClientRef   *outClient
);
Parameters
name

The client's name.

notifyProc

An optional (may be NULL) callback function through which the client will receive notifications of changes to the system.

notifyRefCon

A refCon passed back to notifyRefCon

outClient

On successful return, points to the newly-created MIDIClientRef.

Return Value

A result code.

Discussion

Note that notifyProc will always be called on the run loop which was current when MIDIClientCreate was first called.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIClientDispose

Disposes a MIDIClient object.

OSStatus MIDIClientDispose (
   MIDIClientRef  client
);
Parameters
client

The client to dispose.

Return Value

A result code.

Discussion

It is not essential to call this function; the CoreMIDI framework will automatically dispose all MIDIClients when an application terminates.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIDestinationCreate

Creates a virtual destination in a client.

OSStatus MIDIDestinationCreate (
   MIDIClientRef    client,
   CFStringRef      name,
   MIDIReadProc     readProc,
   void             *refCon,
   MIDIEndpointRef  *outDest
);
Parameters
client

The client owning the virtual destination.

name

The name of the virtual destination.

readProc

The MIDIReadProc to be called when a client sends MIDI to the virtual destination.

refCon

The refCon to be passed to the readProc.

outDest

On successful return, a pointer to the newly-created destination.

Return Value

A result code.

Discussion

The specified readProc gets called when clients send MIDI to your virtual destination.

Drivers need not call this; when they create devices and entities, sources and destinations are created at that time.

After creating a virtual destination, it's a good idea to assign it the same unique ID it had the last time your application created it. (Although you should be prepared for this to fail in the unlikely event of a collision.) This will permit other clients to retain persistent references to your virtual destination more easily.

See the discussion of kMIDIPropertyAdvanceScheduleTimeMuSec for notes about the relationship between when a sender sends MIDI to the destination and when it is received.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIDeviceGetEntity

Returns one of a given device's entities.

MIDIEntityRef MIDIDeviceGetEntity (
   MIDIDeviceRef  device,
   ItemCount      entityIndex0
);
Parameters
device

The device being queried.

entityIndex0

The index (0...MIDIDeviceGetNumberOfEntities(device)-1) of the entity to return

Return Value

A reference to an entity, or NULL if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIDeviceGetNumberOfEntities

Returns the number of entities in a given device.

ItemCount MIDIDeviceGetNumberOfEntities (
   MIDIDeviceRef  device
);
Parameters
device

The device being queried.

Return Value

The number of entities the device contains, or 0 if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEndpointDispose

Disposes a virtual source or destination your client created.

OSStatus MIDIEndpointDispose (
   MIDIEndpointRef  endpt
);
Parameters
endpt

The endpoint to be disposed.

Return Value

A result code.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEndpointGetEntity

Returns an endpoint's entity.

OSStatus MIDIEndpointGetEntity (
   MIDIEndpointRef  inEndpoint,
   MIDIEntityRef    *outEntity
);
Parameters
inEndpoint

The endpoint being queried.

outEntity

On exit, the endpoint's owning entity, or NULL if none.

Discussion

Virtual sources and destinations don't have entities.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEntityGetDestination

Returns one of a given entity's destinations.

MIDIEndpointRef MIDIEntityGetDestination (
   MIDIEntityRef  entity,
   ItemCount      destIndex0
);
Parameters
entity

The entity being queried.

destIndex0

The index (0...MIDIEntityGetNumberOfDestinations(entity) - 1) of the destination to return

Return Value

A reference to a destination, or NULL if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEntityGetDevice

Returns an entity's device.

OSStatus MIDIEntityGetDevice (
   MIDIEntityRef  inEntity,
   MIDIDeviceRef  *outDevice
);
Parameters
inEntity

The entity being queried.

outDevice

On successful return, the entity's owning device.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEntityGetNumberOfDestinations

Returns the number of destinations in a given entity.

ItemCount MIDIEntityGetNumberOfDestinations (
   MIDIEntityRef  entity
);
Parameters
entity

The entity being queried

Return Value

The number of destinations the entity contains, or 0 if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEntityGetNumberOfSources

Returns the number of sources in a given entity.

ItemCount MIDIEntityGetNumberOfSources (
   MIDIEntityRef  entity
);
Parameters
entity

The entity being queried

Return Value

The number of sources the entity contains, or 0 if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEntityGetSource

Returns one of a given entity's sources.

MIDIEndpointRef MIDIEntityGetSource (
   MIDIEntityRef  entity,
   ItemCount      sourceIndex0
);
Parameters
entity

The entity being queried.

sourceIndex0

The index (0...MIDIEntityGetNumberOfSources(entity)-1) of the source to return

Return Value

A reference to a source, or NULL if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIFlushOutput

Unschedules previously-sent packets.

OSStatus MIDIFlushOutput (
   MIDIEndpointRef  dest
);
Parameters
dest

All pending events scheduled to be sent to this destination are unscheduled. If NULL, the operation applies to all destinations.

Discussion

Clients may use MIDIFlushOutput to cancel the sending of packets that were previously scheduled for future delivery.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetDestination

Returns one of the destinations in the system.

MIDIEndpointRef MIDIGetDestination (
   ItemCount  destIndex0
);
Parameters
destIndex0

The index (0...MIDIGetNumberOfDestinations()-1) of the destination to return

Return Value

A reference to a destination, or NULL if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetDevice

Returns one of the devices in the system.

MIDIDeviceRef MIDIGetDevice (
   ItemCount  deviceIndex0
);
Parameters
deviceIndex0

The index (0...MIDIGetNumberOfDevices()-1) of the device to return.

Return Value

A reference to a device, or NULL if an error occurred.

Discussion

Use this to enumerate the devices in the system.

To enumerate the entities in the system, you can walk through the devices, then walk through the devices' entities.

Note: If a client iterates through the devices and entities in the system, it will not ever visit any virtual sources and destinations created by other clients. Also, a device iteration will return devices which are "offline" (were present in the past but are not currently present), while iterations through the system's sources and destinations will not include the endpoints of offline devices.

Thus clients should usually use MIDIGetNumberOfSources, MIDIGetSource, MIDIGetNumberOfDestinations and MIDIGetDestination, rather iterating through devices and entities to locate endpoints.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetExternalDevice

Returns one of the external devices in the system.

MIDIDeviceRef MIDIGetExternalDevice (
   ItemCount  deviceIndex0
);
Parameters
deviceIndex0

The index (0...MIDIGetNumberOfDevices()-1) of the device to return.

Return Value

A reference to a device, or NULL if an error occurred.

Discussion

Use this to enumerate the external devices in the system.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetNumberOfDestinations

Returns the number of destinations in the system.

ItemCount MIDIGetNumberOfDestinations ();
Return Value

The number of destinations in the system, or 0 if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetNumberOfDevices

Returns the number of devices in the system.

ItemCount MIDIGetNumberOfDevices ();
Return Value

The number of devices in the system, or 0 if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetNumberOfExternalDevices

Returns the number of external MIDI devices in the system.

ItemCount MIDIGetNumberOfExternalDevices ();
Return Value

The number of external devices in the system, or 0 if an error occurred.

Discussion

External MIDI devices are MIDI devices connected to driver endpoints via a standard MIDI cable. Their presence is completely optional, only when a UI (such as Audio MIDI Setup) adds them.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetNumberOfSources

Returns the number of sources in the system.

ItemCount MIDIGetNumberOfSources ();
Return Value

The number of sources in the system, or 0 if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIGetSource

Returns one of the sources in the system.

MIDIEndpointRef MIDIGetSource (
   ItemCount  sourceIndex0
);
Parameters
sourceIndex0

The index (0...MIDIGetNumberOfSources()-1) of the source to return

Return Value

A reference to a source, or NULL if an error occurred.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIInputPortCreate

Creates an input port through which the client may receive incoming MIDI messages from any MIDI source.

OSStatus MIDIInputPortCreate (
   MIDIClientRef  client,
   CFStringRef    portName,
   MIDIReadProc   readProc,
   void           *refCon,
   MIDIPortRef    *outPort
);
Parameters
client

The client to own the newly-created port.

portName

The name of the port.

readProc

The MIDIReadProc which will be called with incoming MIDI, from sources connected to this port.

refCon

The refCon passed to readHook.

outPort

On successful return, points to the newly-created MIDIPort.

Return Value

A result code.

Discussion

After creating a port, use MIDIPortConnectSource to establish an input connection from any number of sources to your port.

readProc will be called on a separate high-priority thread owned by CoreMIDI.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectFindByUniqueID

Locates a device, external device, entity, or endpoint by its uniqueID.

OSStatus MIDIObjectFindByUniqueID (
   MIDIUniqueID    inUniqueID,
   MIDIObjectRef   *outObject,
   MIDIObjectType  *outObjectType
);
Parameters
inUniqueID

The uniqueID of the object to search for. (This should be the result of an earlier call to MIDIObjectGetIntegerProperty for the property kMIDIPropertyUniqueID).

outObject

The returned object, or NULL if the object was not found or an error occurred. This should be cast to the appropriate type (MIDIDeviceRef, MIDIEntityRef, MIDIEndpointRef), according to *outObjectType.

outObjectType

On exit, the type of object which was found; undefined if none found.

Return Value

An OSStatus error code, including kMIDIObjectNotFound if there is no object with the specified uniqueID.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectGetDataProperty

Gets an object's data-type property.

OSStatus MIDIObjectGetDataProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID,
   CFDataRef      *outData
);
Parameters
obj

The object whose property is to be returned.

propertyID

Name of the property to return.

outData

On successful return, the value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectGetDictionaryProperty

Gets an object's dictionary-type property.

OSStatus MIDIObjectGetDictionaryProperty (
   MIDIObjectRef    obj,
   CFStringRef      propertyID,
   CFDictionaryRef  *outDict
);
Parameters
obj

The object whose property is to be returned.

propertyID

Name of the property to return.

outDict

On successful return, the value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectGetIntegerProperty

Gets an object's integer-type property.

OSStatus MIDIObjectGetIntegerProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID,
   SInt32         *outValue
);
Parameters
obj

The object whose property is to be returned.

propertyID

Name of the property to return.

outValue

On successful return, the value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectGetProperties

Gets all of an object's properties.

OSStatus MIDIObjectGetProperties (
   MIDIObjectRef      obj,
   CFPropertyListRef  *outProperties,
   Boolean            deep
);
Parameters
obj

The object whose properties are to be returned.

outProperties

On successful return, the object's properties.

deep

true if the object's child objects are to be included (e.g. a device's entities, or an entity's endpoints).

Return Value

A result code.

Discussion

Returns a CFPropertyList of all of an object's properties. The property list may be a dictionary or an array. Dictionaries map property names (CFString) to values, which may be CFNumber, CFString, or CFData. Arrays are arrays of such values.

Properties which an object inherits from its owning object (if any) are not included.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectGetStringProperty

Gets an object's string-type property.

OSStatus MIDIObjectGetStringProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID,
   CFStringRef    *str
);
Parameters
obj

The object whose property is to be returned.

propertyID

Name of the property to return.

str

On successful return, the value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectRemoveProperty

Removes an object's property.

OSStatus MIDIObjectRemoveProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID
);
Parameters
obj

The object whose property is to be removed.

propertyID

The property to be removed.

Return Value

A result code.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectSetDataProperty

Sets an object's data-type property.

OSStatus MIDIObjectSetDataProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID,
   CFDataRef      data
);
Parameters
obj

The object whose property is to be altered.

propertyID

Name of the property to set.

data

New value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectSetDictionaryProperty

Sets an object's dictionary-type property.

OSStatus MIDIObjectSetDictionaryProperty (
   MIDIObjectRef    obj,
   CFStringRef      propertyID,
   CFDictionaryRef  data
);
Parameters
obj

The object whose property is to be altered.

propertyID

Name of the property to set.

dict

New value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectSetIntegerProperty

Sets an object's integer-type property.

OSStatus MIDIObjectSetIntegerProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID,
   SInt32         value
);
Parameters
obj

The object whose property is to be altered.

propertyID

Name of the property to set.

value

New value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectSetStringProperty

Sets an object's string-type property.

OSStatus MIDIObjectSetStringProperty (
   MIDIObjectRef  obj,
   CFStringRef    propertyID,
   CFStringRef    str
);
Parameters
obj

The object whose property is to be altered.

propertyID

Name of the property to set.

str

New value of the property.

Return Value

A result code.

Discussion

(See the MIDIObjectRef documentation for information about properties.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIOutputPortCreate

Creates an output port through which the client may send outgoing MIDI messages to any MIDI destination.

OSStatus MIDIOutputPortCreate (
   MIDIClientRef  client,
   CFStringRef    portName,
   MIDIPortRef    *outPort
);
Parameters
client

The client to own the newly-created port

portName

The name of the port.

outPort

On successful return, points to the newly-created MIDIPort.

Return Value

A result code.

Discussion

Output ports provide a mechanism for MIDI merging. CoreMIDI assumes that each output port will be responsible for sending only a single MIDI stream to each destination, although a single port may address all of the destinations in the system.

Multiple output ports are only necessary when an application is capable of directing multiple simultaneous MIDI streams to the same destination.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPacketListAdd

Adds a MIDI event to a MIDIPacketList.

(MIDIPacket *) MIDIPacketListAdd (
   MIDIPacketList  *pktlist,
   ByteCount       listSize,
   MIDIPacket      *curPacket,
   MIDITimeStamp   time,
   ByteCount       nData,
   const Byte      *data
);
Parameters
pktlist

The packet list to which the event is to be added.

listSize

The size, in bytes, of the packet list.

curPacket

A packet pointer returned by a previous call to MIDIPacketListInit or MIDIPacketListAdd for this packet list.

time

The new event's time.

nData

The length of the new event, in bytes.

data

The new event. May be a single MIDI event, or a partial sys-ex event. Running status is not permitted.

Return Value

Returns null if there was not room in the packet for the event; otherwise returns a packet pointer which should be passed as curPacket in a subsequent call to this function.

Discussion

The maximum size of a packet list is 65536 bytes. Large sysex messages must be sent in smaller packet lists.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPacketListInit

Prepares a MIDIPacketList to be built up dynamically.

(MIDIPacket *) MIDIPacketListInit (
   MIDIPacketList  *pktlist
);
Parameters
pktlist

The packet list to be initialized.

Return Value

A pointer to the first MIDIPacket in the packet list.

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPacketNext

Advances a MIDIPacket pointer to the MIDIPacket that immediately follows a given packet in memory, for packets that are part of a MIDIPacketList array.

(MIDIPacket *) MIDIPacketNext (
   MIDIPacket  *pkt
);
Parameters
pkt

A pointer to a MIDIPacket in a MIDIPacketList array.

Return Value

The subsequent packet in the MIDIPacketList array.

Discussion

This is implemented as a macro for efficiency and to avoid const problems. Refer to the MIDIServices.h header file for the macro implementation.

MIDIPortConnectSource

Establishes a connection from a source to a client's input port.

OSStatus MIDIPortConnectSource (
   MIDIPortRef      port,
   MIDIEndpointRef  source,
   void             *connRefCon
);
Parameters
port

The port to which to create the connection. This port's readProc is called with incoming MIDI from the source.

source

The source from which to create the connection.

connRefCon

This refCon is passed to the MIDIReadProc, as a way to identify the source.

Return Value

A result code.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPortDisconnectSource

Closes a previously-established source-to-input port connection.

OSStatus MIDIPortDisconnectSource (
   MIDIPortRef      port,
   MIDIEndpointRef  source
);
Parameters
port

The port whose connection is being closed.

source

The source from which to close a connection to the specified port.

Return Value

A result code.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPortDispose

Disposes a MIDIPort object.

OSStatus MIDIPortDispose (
   MIDIPortRef  port
);
Parameters
port

The port to dispose.

Return Value

A result code.

Discussion

It is not usually necessary to call this function; when an application's MIDIClient's are automatically disposed at termination, or explicitly, via MIDIClientDispose, the client's ports are automatically disposed at that time.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIReceived

Distributes incoming MIDI from a source to the client input ports which are connected to that source.

OSStatus MIDIReceived (
   MIDIEndpointRef       src,
   const MIDIPacketList  *pktlist
);
Parameters
src

The source which is transmitting MIDI.

pktlist

The MIDI events to be transmitted.

Return Value

A result code.

Discussion

Drivers should call this function when receiving MIDI from a source.

Clients which have created virtual sources, using MIDISourceCreate, should call this function when the source is generating MIDI.

Unlike MIDISend(), a timestamp of 0 is not equivalent to "now"; the driver or virtual source is responsible for putting proper timestamps in the packets.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIRestart

Stops and restarts MIDI I/O.

OSStatus MIDIRestart ();
Return Value

A result code.

Discussion

This is useful for forcing CoreMIDI to ask its drivers to rescan for hardware.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDISend

Sends MIDI to a destination.

OSStatus MIDISend (
   MIDIPortRef           port,
   MIDIEndpointRef       dest,
   const MIDIPacketList  *pktlist
);
Parameters
port

The output port through which the MIDI is to be sent.

dest

The destination to receive the events.

pktlist

The MIDI events to be sent.

Return Value

A result code.

Discussion

Events with future timestamps are scheduled for future delivery. CoreMIDI performs any needed MIDI merging.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDISendSysex

Sends a single system-exclusive event, asynchronously.

OSStatus MIDISendSysex (
   MIDISysexSendRequest  *request
);
Parameters
request

Contains the destination, and a pointer to the MIDI data to be sent.

Return Value

A result code.

Discussion

request->data must point to a single MIDI system-exclusive message, or portion thereof.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDISourceCreate

Creates a virtual source in a client.

OSStatus MIDISourceCreate (
   MIDIClientRef    client,
   CFStringRef      name,
   MIDIEndpointRef  *outSrc
);
Parameters
client

The client owning the virtual source.

name

The name of the virtual source.

outSrc

On successful return, a pointer to the newly-created source.

Return Value

A result code.

Discussion

Drivers need not call this; when they create devices and entities, sources and destinations are created at that time.

After creating a virtual source, use MIDIReceived to transmit MIDI messages from your virtual source to any clients connected to the virtual source.

After creating a virtual source, it's a good idea to assign it the same unique ID it had the last time your application created it. (Although you should be prepared for this to fail in the unlikely event of a collision.) This will permit other clients to retain persistent references to your virtual source more easily.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

Callbacks

MIDICompletionProc

Called when a MIDI system-exclusive event has been completely sent or has been aborted.

typedef void (*MIDICompletionProc) (
   MIDISysexSendRequest  *request
);

If you named your callback function MyMIDICompletionHander, you would declare it like this:

void MyMIDICompletionHander (
   MIDISysexSendRequest  *request
);

Parameters
request

The MIDISysexSendRequest which has completed, or been aborted.

Discussion

Use this callback function to notify your app of the completion of a call to the MIDISendSysex function.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDINotifyProc

Called when the MIDI state changes.

typedef void (*MIDINotifyProc) (
   const MIDINotification  *message,
   void                    *refCon
);

If you named your callback function MyMIDIStateChangedHander, you would declare it like this:

void MyMIDIStateChangedHander (
   const MIDINotification  *message,
   void                    *refCon
);

Parameters
message

Information about the state change.

refCon

The context you provided to the MIDIClientCreate function.

Discussion

The MIDINotifyProc callback function is invoked on the same thread on which you called the MIDIClientCreate function.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIReadProc

Called when the system has one or more incoming MIDI messages to deliver to your app.

typedef void (*MIDIReadProc) (
   const MIDIPacketList  *pktlist,
   void                  *readProcRefCon,
   void                  *srcConnRefCon
);

If you named your callback function MyIncomingMIDIMessageHander, you would declare it like this:

void MIDIReadProc (
   const MIDIPacketList  *pktlist,
   void                  *readProcRefCon,
   void                  *srcConnRefCon
);

Parameters
pktlist

The incoming MIDI message or messages.

readProcRefCon

The context you provided to the MIDIInputPortCreate or MIDIDestinationCreate function.

srcConnRefCon

The context you provided to the MIDIPortConnectSource function, which identifies the source of the data.

Discussion

When you call the MIDIInputPortCreate or MIDIDestinationCreate function, you provide a pointer to your MIDIReadProc callback. The system creates a high-priority receive thread on your behalf. Because your MIDIReadProc callback is invoked from a separate thread, be aware of the synchronization issues when using data provided by this callback.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

Data Types

MIDIClientRef

An object maintaining per-client state.

typedef MIDIObjectRef MIDIClientRef;
Discussion

Derives from MIDIObjectRef, does not have an owner object.

To use CoreMIDI, an application creates a MIDIClientRef, to which it can add MIDIPortRef's, through which it can send and receive MIDI.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIDeviceRef

A MIDI device or external device, containing entities.

typedef MIDIObjectRef MIDIDeviceRef;
Discussion

Derives from MIDIObjectRef, does not have an owner object.

A MIDI device, which either attaches directly to the computer and is controlled by a MIDI driver, or which is "external," meaning that it is connected to a driver-controlled device via a standard MIDI cable.

A MIDIDeviceRef has properties and contains MIDIEntityRef's.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEndpointRef

A MIDI source or destination, owned by an entity.

typedef MIDIObjectRef MIDIEndpointRef;
Discussion

Derives from MIDIObjectRef, owned by a MIDIEntityRef, unless it is a virtual endpoint, in which case there is no owning entity.

Entities have any number of MIDIEndpointRef's, sources and destinations of 16-channel MIDI streams.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIEntityRef

A MIDI entity, owned by a device, containing endpoints.

typedef MIDIObjectRef MIDIEntityRef;
Discussion

Derives from MIDIObjectRef, owned by a MIDIDeviceRef.

Devices may have multiple logically distinct sub-components, e.g. a MIDI synthesizer and a pair of MIDI ports, both addressable via a USB port.

By grouping a device's endpoints into entities, the system has enough information for an application to make reasonable assumptions about how to communicate in a bi-directional manner with each entity, as is desirable in MIDI librarian applications.

These sub-components are MIDIEntityRef's.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectRef

The base class of many CoreMIDI objects.

typedef UInt32 MIDIObjectRef;
Discussion

MIDIObject is the base class for many of the objects in CoreMIDI. They have properties, and often an "owner" object, from which they inherit any properties they do not themselves have.

Developers may add their own private properties, whose names must begin with their company's inverted domain name, as in Java package names, but with underscores instead of dots, e.g.: com_apple_APrivateAppleProperty

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPortRef

A MIDI connection port owned by a client.

typedef MIDIObjectRef MIDIPortRef;
Discussion

Derives from MIDIObjectRef, owned by a MIDIClientRef.

A MIDIPortRef, which may be an input port or output port, is an object through which a client may communicate with any number of MIDI sources or destinations.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDITimeStamp

A host clock time.

typedef UInt64 MIDITimeStamp;
Discussion

A host clock time representing the time of an event, as returned by mach_absolute_time() or UpTime().

Since MIDI applications will tend to do a fair amount of math with the times of events, it's more convenient to use a UInt64 than an AbsoluteTime.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIUniqueID

A unique identifier for a MIDIObjectRef.

typedef SInt32 MIDIUniqueID;
Discussion

An integer which uniquely identifies a MIDIObjectRef.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDINotification

A message describing a system state change.

struct MIDINotification {
   MIDINotificationMessageID  messageID;
   UInt32                     messageSize;
   // additional data may follow, depending on messageID
};
typedef struct MIDINotification MIDINotification;
Fields
messageID

type of message

messageSize

size of the entire message, including messageID and messageSize

Discussion

A MIDINotification is a structure passed to a MIDINotifyProc, when CoreMIDI wishes to inform a client of a change in the state of the system.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectAddRemoveNotification

A message describing the addition or removal of an object.

struct MIDIObjectAddRemoveNotification {
   MIDINotificationMessageID  messageID;
   UInt32                     messageSize;
   MIDIObjectRef              parent;
   MIDIObjectType             parentType;
   MIDIObjectRef              child;
   MIDIObjectType             childType;
};
typedef struct MIDIObjectAddRemoveNotification MIDIObjectAddRemoveNotification;
Fields
messageID

type of message

messageSize

size of the entire message, including messageID and messageSize

parent

the parent of the added or removed object (possibly NULL)

parentType

the type of the parent object (undefined if parent is NULL)

child

the added or removed object

childType

the type of the added or removed object

Discussion

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIObjectPropertyChangeNotification

A message describing the addition or removal of an object.

struct MIDIObjectPropertyChangeNotification {
   MIDINotificationMessageID  messageID;
   UInt32                     messageSize;
   MIDIObjectRef              object;
   MIDIObjectType             objectType;
   CFStringRef                propertyName;
};
typedef struct MIDIObjectPropertyChangeNotification MIDIObjectPropertyChangeNotification;
Fields
messageID

The type of message.

messageSize

The size of the entire message, including the messageID and messageSize fields.

object

The object whose property has changed.

objectType

The type of the object whose property has changed.

propertyName

The name of the changed property.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIIOErrorNotification

A message describing a MIDI I/O error.

struct MIDIIOErrorNotification {
   MIDINotificationMessageID  messageID;
   UInt32                     messageSize;
   MIDIDeviceRef              driverDevice;
   OSStatus                   errorCode;
};
typedef struct MIDIIOErrorNotification MIDIIOErrorNotification;
Fields
messageID

The type of message.

messageSize

The size of the entire message, including the messageID and messageSize fields.

driverDevice

The I/O driver that exhibited an error.

errorCode

An error code.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPacket

A collection of simultaneous MIDI events.

struct MIDIPacket {
   MIDITimeStamp  timeStamp;
   UInt16         length;
   Byte           data[256];
};
typedef struct MIDIPacket MIDIPacket;
Fields
timeStamp

The time at which the events occurred, if receiving MIDI, or, if sending MIDI, the time at which the events are to be played. Zero means "now." The time stamp applies to the first MIDI byte in the packet.

length

The number of valid MIDI bytes which follow, in data. (It may be larger than 256 bytes if the packet is dynamically allocated.)

data

A variable-length stream of MIDI messages. Running status is not allowed. In the case of system-exclusive messages, a packet may only contain a single message, or portion of one, with no other MIDI events.

Discussion

The MIDI messages in the packet must always be complete, except for system-exclusive.

(This is declared to be 256 bytes in length so clients don't have to create custom data structures in simple situations.)

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDIPacketList

A list of MIDI events being received from, or being sent to, one endpoint.

struct MIDIPacketList {
   UInt32      numPackets;
   MIDIPacket  packet[1];
};
typedef struct MIDIPacketList MIDIPacketList;
Fields
numPackets

The number of MIDIPackets in the list.

packet

An open-ended array of variable-length MIDIPackets.

Discussion

The timestamps in the packet list must be in ascending order.

Note that the packets in the list, while defined as an array, may not be accessed as an array, since they are variable-length. To iterate through the packets in a packet list, use a loop such as:

MIDIPacket *packet = &packetList->packet[0];
for (int i = 0; i > packetList->numPackets; ++i) {
    // ...
    packet = MIDIPacketNext (packet);
}
Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

MIDISysexSendRequest

A request to transmit a system-exclusive event.

struct MIDISysexSendRequest {
   MIDIEndpointRef     destination;
   const Byte          *data;
   UInt32              bytesToSend;
   Boolean             complete;
   Byte                reserved[3];
   MIDICompletionProc  completionProc;
   void                *completionRefCon;
};
typedef struct MIDISysexSendRequest MIDISysexSendRequest;
Fields
destination

The endpoint to which the event is to be sent.

data

Initially, a pointer to the sys-ex event to be sent. MIDISendSysex will advance this pointer as bytes are sent.

bytesToSend

Initially, the number of bytes to be sent. MIDISendSysex will decrement this counter as bytes are sent.

complete

The client may set this to true at any time to abort transmission. The implementation sets this to true when all bytes have been sent.

completionProc

Called when all bytes have been sent, or after the client has set complete to true.

completionRefCon

Passed as a refCon to completionProc.

Discussion

This represents a request to send a single system-exclusive MIDI event to a MIDI destination asynchronously.

Availability
  • Available in iOS 4.2 and later.
Declared In
MIDIServices.h

Constants

Global Constants

const CFStringRef kMIDIPropertyAdvanceScheduleTimeMuSec;
const CFStringRef kMIDIPropertyCanRoute;
const CFStringRef kMIDIPropertyConnectionUniqueID;
const CFStringRef kMIDIPropertyDeviceID;
const CFStringRef kMIDIPropertyDisplayName;
const CFStringRef kMIDIPropertyDriverDeviceEditorApp;
const CFStringRef kMIDIPropertyDriverOwner;
const CFStringRef kMIDIPropertyDriverVersion;
const CFStringRef kMIDIPropertyImage;
const CFStringRef kMIDIPropertyIsBroadcast;
const CFStringRef kMIDIPropertyIsDrumMachine;
const CFStringRef kMIDIPropertyIsEffectUnit;
const CFStringRef kMIDIPropertyIsEmbeddedEntity;
const CFStringRef kMIDIPropertyIsMixer;
const CFStringRef kMIDIPropertyIsSampler;
const CFStringRef kMIDIPropertyManufacturer;
const CFStringRef kMIDIPropertyMaxReceiveChannels;
const CFStringRef kMIDIPropertyMaxSysExSpeed;
const CFStringRef kMIDIPropertyMaxTransmitChannels;
const CFStringRef kMIDIPropertyModel;
const CFStringRef kMIDIPropertyName;
const CFStringRef kMIDIPropertyNameConfiguration;
const CFStringRef kMIDIPropertyOffline;
const CFStringRef kMIDIPropertyPanDisruptsStereo;
const CFStringRef kMIDIPropertyPrivate;
const CFStringRef kMIDIPropertyReceiveChannels;
const CFStringRef kMIDIPropertyReceivesBankSelectLSB;
const CFStringRef kMIDIPropertyReceivesBankSelectMSB;
const CFStringRef kMIDIPropertyReceivesClock;
const CFStringRef kMIDIPropertyReceivesMTC;
const CFStringRef kMIDIPropertyReceivesNotes;
const CFStringRef kMIDIPropertyReceivesProgramChanges;
const CFStringRef kMIDIPropertySingleRealtimeEntity;
const CFStringRef kMIDIPropertySupportsGeneralMIDI;
const CFStringRef kMIDIPropertySupportsMMC;
const CFStringRef kMIDIPropertySupportsShowControl;
const CFStringRef kMIDIPropertyTransmitChannels;
const CFStringRef kMIDIPropertyTransmitsBankSelectLSB;
const CFStringRef kMIDIPropertyTransmitsBankSelectMSB;
const CFStringRef kMIDIPropertyTransmitsClock;
const CFStringRef kMIDIPropertyTransmitsMTC;
const CFStringRef kMIDIPropertyTransmitsNotes;
const CFStringRef kMIDIPropertyTransmitsProgramChanges;
const CFStringRef kMIDIPropertyUniqueID;
Constants
kMIDIPropertyAdvanceScheduleTimeMuSec

device/entity/endpoint property, integer

Set by the owning driver; should not be touched by other clients. If it is non-zero, then it is a recommendation of how many microseconds in advance clients should schedule output. Clients should treat this value as a minimum. For devices with a non-zero advance schedule time, drivers will receive outgoing messages to the device at the time they are sent by the client, via MIDISend, and the driver is responsible for scheduling events to be played at the right times according to their timestamps.

As of CoreMIDI 1.3, this property may also be set on virtual destinations (but only the creator of the destination should do so). When a client sends to a virtual destination with an advance schedule time of 0, the virtual destination receives its messages at their scheduled delivery time. If a virtual destination has a non-zero advance schedule time, it receives timestamped messages as soon as they are sent, and must do its own internal scheduling of received events.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyCanRoute

// e.g. is patch bay

device/entity property, integer (0/1). Indicates whether the device or entity can route MIDI messages to or from other external MIDI devices (as with MIDI patch bays). This should NOT be set on devices which are controlled by drivers.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyConnectionUniqueID

device/entity/endpoint property, integer or CFDataRef

UniqueID of an external device/entity/endpoint attached to this one. As of Mac OS X 10.3, Audio MIDI Setup maintains endpoint-to-external endpoint connections (in 10.2, it connected devices to devices). The property is non-existant or 0 if there is no connection.

New for CoreMIDI 1.1 (Mac OS X 10.1)

Beginning with CoreMIDI 1.3, this property may also be a CFDataRef containing an array of big-endian SInt32's, to allow specifying that a driver object connects to multiple external objects (via MIDI thru-ing or splitting).

This property may also exist for external devices/entities/endpoints, in which case it signifies a MIDI Thru connection to another external device/entity/endpoint (again, it is strongly recommended that it be an endpoint).

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyDeviceID

device/entity property, integer

The entity's system-exclusive ID, in user-visible form

Drivers may set this property on their devices or entities.

Setup editors may allow the user to set this property on external devices.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyDisplayName

device/entity/endpoint property, string.

Provides the Apple-recommended user-visible name for an endpoint, by combining the device and endpoint names.

For objects other than endpoints, the display name is the same as the name.

New for CoreMIDI 1.5.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyDriverDeviceEditorApp

device property, string, contains the full path to an application which knows how to configure this driver-owned devices. Drivers may set this property on their owned devices. Applications must not write to it.

New for CoreMIDI 1.4.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyDriverOwner

device/entity/endpoint property, string

Name of the driver that owns a device. Set by the owning driver, on the device; should not be touched by other clients. Property is inherited from the device by its entities and endpoints.

New for CoreMIDI 1.1 (Mac OS X 10.1)

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyDriverVersion

device/entity/endpoint property, integer, returns the driver version API of the owning driver (only for driver- owned devices). Drivers need not set this property; applications should not write to it.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyImage

device property, CFStringRef which is a full POSIX path to a device or external device's icon, stored in any standard graphic file format such as JPEG, GIF, PNG and TIFF are all acceptable. (See CFURL for functions to convert between POSIX paths and other ways of specifying files.) The image's maximum size should be 128x128.

Drivers should set the icon on the devices they add.

A studio setup editor should allow the user to choose icons for external devices.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyIsBroadcast

entity/endpoint property, integer

1 if the endpoint broadcasts messages to all of the other endpoints in the device, 0 if not. Set by the owning driver; should not be touched by other clients. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyIsDrumMachine

device/entity property, integer (0/1). Indicates whether the device or entity's sound presets tend to be collections of non-transposable samples (e.g. drum kits).

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyIsEffectUnit

device/entity property, integer (0/1). Indicates whether the device or entity is primarily a MIDI-controlled audio effect unit (i.e. does not generate sound on its own).

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyIsEmbeddedEntity

entity/endpoint property, integer

0 if there are external MIDI connectors, 1 if not. New for CoreMIDI 1.1 (Mac OS X 10.1)

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyIsMixer

device/entity property, integer (0/1). Indicates whether the device or entity mixes external audio signals, controlled by MIDI messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyIsSampler

device/entity property, integer (0/1). Indicates whether the device or entity plays audio samples in response to MIDI note messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyManufacturer

device/endpoint property, string

Drivers should set this property on their devices.

Setup editors may allow the user to set this property on external devices.

Creators of virtual endpoints may set this property on their endpoints.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyMaxReceiveChannels

device/entity property, integer (0-16). Indicates the maximum number of MIDI channels on which a device may simultaneously receive MIDI Channel Messages. Common values are 0 (devices which only respond to System Messages), 1 (non-multitimbral devices), and 16 (fully multitimbral devices). Other values are possible, for example devices which are multitimbral but have fewer than 16 "parts".

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyMaxSysExSpeed

device/entity/endpoint property, integer

Set by the owning driver; should not be touched by other clients. The value is the maximum rate, in bytes/second, at which sysex messages may be sent reliably to this object. (The default value is 3125, as with MIDI 1.0)

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyMaxTransmitChannels

device/entity property, integer (0/1). Indicates the maximum number of MIDI channels on which a device may simultaneously transmit MIDI Channel Messages. Common values are 0, 1 and 16.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyModel

device/endpoint property, string

Drivers should set this property on their devices.

Setup editors may allow the user to set this property on external devices.

Creators of virtual endpoints may set this property on their endpoints.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyName

device/entity/endpoint property, string

Devices, entities, and endpoints may all have names. The recommended way to display an endpoint's name is to ask for the endpoint name, and display only that name if it is unique. If it is non-unique, prepend the device name.

A setup editor may allow the user to set the names of both driver-owned and external devices.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyNameConfiguration

device/entity/endpoint property, CFDictionary

This specifies the device's current patch, note and control name values using the MIDINameDocument XML format. This specification requires the use of higher-level, OS-specific constructs outside of the specification, to fully define the current names for a device.

The MIDINameConfiguration property is implemented as a CFDictionary:

key "master" maps to a CFDataRef containing an AliasHandle referring to the device's master name document.

key "banks" maps to a CFDictionaryRef. This dictionary's keys are CFStringRef names of patchBank elements in the master document, and its values are each a CFDictionaryRef: key "file" maps to a CFDataRef containing an AliasHandle to a document containing patches that override those in the master document, and key "patchNameList" maps to a CFStringRef which is the name of the patchNameList element in the overriding document.

key "currentChannelNameSets" maps to a 16-element CFArrayRef, each element of which is a CFStringRef of the name of the current mode for each of the 16 MIDI channels.

key "currentDeviceMode" maps to a CFStringRef containing the name of the device's mode.

Clients setting this property must take particular care to preserve dictionary values other than the ones they are interested in changing, and to properly structure the dictionary.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyOffline

device/entity/endpoint property, integer

1 = device is offline (is temporarily absent), 0 = present. Set by the owning driver, on the device; should not be touched by other clients. Property is inherited from the device by its entities and endpoints. New for CoreMIDI 1.1 (Mac OS X 10.1)

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyPanDisruptsStereo

device/entity property, integer (0/1). Indicates whether the MIDI pan messages (control 10), when sent to the device or entity, cause undesirable effects when playing stereo sounds (e.g. converting the signal to mono). New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyPrivate

device/entity/endpoint property, integer

1 = endpoint is private, hidden from other clients. May be set on a device or entity, but they will still appear in the API; only affects whether the owned endpoints are hidden. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceiveChannels

endpoint property, integer

The value is a bitmap of channels on which the object receives: 1=ch 1, 2=ch 2, 4=ch 3 ... 0x8000=ch 16.

Drivers may set this property on their entities or endpoints.

Setup editors may allow the user to set this property on external endpoints.

Virtual destination may set this property on their endpoints.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceivesBankSelectLSB

device/entity property, integer (0/1). Indicates whether the device or entity responds to MIDI bank select LSB messages (control 32).

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceivesBankSelectMSB

device/entity property, integer (0/1). Indicates whether the device or entity responds to MIDI bank select MSB messages (control 0).

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceivesClock

device/entity property, integer (0/1). Indicates whether the device or entity responds to MIDI beat clock messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceivesMTC

device/entity property, integer (0/1). Indicates whether the device or entity responds to MIDI Time Code messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceivesNotes

device/entity property, integer (0/1). Indicates whether the device or entity responds to MIDI Note On messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyReceivesProgramChanges

device/entity property, integer (0/1). Indicates whether the device or entity responds to MIDI program change messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertySingleRealtimeEntity

device property, integer

Some MIDI interfaces cannot route MIDI realtime messages to individual outputs; they are broadcast. On such devices the inverse is usually also true -- incoming realtime messages cannot be identified as originating from any particular source.

When this property is set on a driver device, it signifies the 0-based index of the entity on which incoming realtime messages from the device will appear to have originated from.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertySupportsGeneralMIDI

device/entity property, integer (0/1). Indicates whether the device or entity implements the General MIDI specification.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertySupportsMMC

device/entity property, integer (0/1). Indicates whether the device or entity implements the MIDI Machine Control portion of the MIDI specification.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertySupportsShowControl

device/entity property, integer (0/1). Indicates whether the device implements the MIDI Show Control specification.

New for CoreMIDI 1.5.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitChannels

endpoint property, integer

The value is a bitmap of channels on which the object transmits: 1=ch 1, 2=ch 2, 4=ch 3 ... 0x8000=ch 16.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitsBankSelectLSB

device/entity property, integer (0/1). Indicates whether the device or entity transmits MIDI bank select LSB messages (control 32).

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitsBankSelectMSB

device/entity property, integer (0/1). Indicates whether the device or entity transmits MIDI bank select MSB messages (control 0).

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitsClock

device/entity property, integer (0/1). Indicates whether the device or entity transmits MIDI beat clock messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitsMTC

device/entity property, integer (0/1). Indicates whether the device or entity transmits MIDI Time Code messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitsNotes

device/entity property, integer (0/1). Indicates whether the device or entity transmits MIDI note messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyTransmitsProgramChanges

device/entity property, integer (0/1). Indicates whether the device or entity transmits MIDI program change messages.

New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIPropertyUniqueID

devices, entities, endpoints all have unique ID's, integer

The system assigns unique ID's to all objects. Creators of virtual endpoints may set this property on their endpoints, though doing so may fail if the chosen ID is not unique.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

Error Constants

The error constants unique to Core MIDI.

enum {
   kMIDIInvalidClient      = -10830,
   kMIDIInvalidPort        = -10831,
   kMIDIWrongEndpointType  = -10832,
   kMIDINoConnection       = -10833,
   kMIDIUnknownEndpoint    = -10834,
   kMIDIUnknownProperty    = -10835,
   kMIDIWrongPropertyType  = -10836,
   kMIDINoCurrentSetup     = -10837,
   kMIDIMessageSendErr     = -10838,
   kMIDIServerStartErr     = -10839,
   kMIDISetupFormatErr     = -10840,
   kMIDIWrongThread        = -10841,
   kMIDIObjectNotFound     = -10842,
   kMIDIIDNotUnique        = -10843
};
Constants
kMIDIInvalidClient

An invalid MIDIClientRef was passed.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIInvalidPort

An invalid MIDIPortRef was passed.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIWrongEndpointType

A source endpoint was passed to a function expecting a destination, or vice versa.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDINoConnection

Attempt to close a non-existant connection.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIUnknownEndpoint

An invalid MIDIEndpointRef was passed.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIUnknownProperty

Attempt to query a property not set on the object.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIWrongPropertyType

Attempt to set a property with a value not of the correct type.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDINoCurrentSetup

Internal error; there is no current MIDI setup object.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMessageSendErr

Communication with MIDIServer failed.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIServerStartErr

Unable to start MIDIServer.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDISetupFormatErr

Unable to read the saved state.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIWrongThread

A driver is calling a non-I/O function in the server from a thread other than the server's main thread.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectNotFound

The requested object does not exist.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIIDNotUnique

Attempt to set a non-unique kMIDIPropertyUniqueID on an object.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

Discussion

These are the error constants that are unique to Core MIDI. Note that Core MIDI functions may return other codes that are not listed here.

MIDINotificationMessageID

Signifies the type of a MIDINotification.

enum {
   kMIDIMsgSetupChanged            = 1,
   kMIDIMsgObjectAdded             = 2,
   kMIDIMsgObjectRemoved           = 3,
   kMIDIMsgPropertyChanged         = 4,
   kMIDIMsgThruConnectionsChanged  = 5,
   kMIDIMsgSerialPortOwnerChanged  = 6,
   kMIDIMsgIOError                 = 7
};
typedef SInt32 MIDINotificationMessageID;
Constants
kMIDIMsgSetupChanged

Some aspect of the current MIDISetup has changed. No data. Should ignore this message if messages 2-6 are handled.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMsgObjectAdded

A device, entity or endpoint was added. Structure is MIDIObjectAddRemoveNotification. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMsgObjectRemoved

A device, entity or endpoint was removed. Structure is MIDIObjectAddRemoveNotification. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMsgPropertyChanged

An object's property was changed. Structure is MIDIObjectPropertyChangeNotification. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMsgThruConnectionsChanged

A persistent MIDI Thru connection was created or destroyed. No data. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMsgSerialPortOwnerChanged

A persistent MIDI Thru connection was created or destroyed. No data. New for CoreMIDI 1.3.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIMsgIOError

A driver I/O error occurred.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

Discussion

MIDIObjectType

Indicates the type of a MIDI object.

enum {
   kMIDIObjectType_Other                = -1,
   kMIDIObjectType_Device               = 0,
   kMIDIObjectType_Entity               = 1,
   kMIDIObjectType_Source               = 2,
   kMIDIObjectType_Destination          = 3,
   kMIDIObjectType_ExternalMask         = 0x10,
   kMIDIObjectType_ExternalDevice       =
   kMIDIObjectType_ExternalMask | kMIDIObjectType_Device,
   kMIDIObjectType_ExternalEntity       =
   kMIDIObjectType_ExternalMask | kMIDIObjectType_Entity,
   kMIDIObjectType_ExternalSource       =
   kMIDIObjectType_ExternalMask | kMIDIObjectType_Source,
   kMIDIObjectType_ExternalDestination  =
   kMIDIObjectType_ExternalMask | kMIDIObjectType_Destination
};
typedef SInt32 MIDIObjectType;
Constants
kMIDIObjectType_Other

An unspecified MIDI object type.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_Device

A MIDI device.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_Entity

A MIDI entity.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_Source

A MIDI source.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_Destination

A MIDI destination.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_ExternalMask

Bit mask for indicating that a device is external.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_ExternalDevice

An external MIDI device.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_ExternalEntity

An external MIDI entity.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_ExternalSource

An external MIDI source.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

kMIDIObjectType_ExternalDestination

An external MIDI destination.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.

Discussion

Signifies the real type of a MIDIObjectRef instance.

kMIDIInvalidUniqueID

Indicates that the MIDI unique ID is not valid.

enum {
   kMIDIInvalidUniqueID = 0
};
Constants
kMIDIInvalidUniqueID

The MIDI unique ID is not valid.

Available in iOS 4.2 and later.

Declared in MIDIServices.h.