Mac Dev Center Mac OS X Reference Library Drivers, Kernel, & Hardware: User-Space Device Access I/O Kit Framework Reference

IOAudioTypes.h

Includes:

Overview

Use the links in the table of contents to the left to access the documentation.

Typedefs

IOAudioControlCalls: The set of constants passed to IOAudioControlUserClient::getExternalMethodForIndex() when making calls from the IOAudioFamily user client code.
IOAudioControlNotifications: The set of constants passed in the type field of IOAudioControlUserClient::registerNotificaitonPort().
IOAudioEngineCalls: The set of constants passed to IOAudioEngineUserClient::getExternalMethodForIndex() when making calls from the IOAudioFamily user client code.
IOAudioEngineMemory: Used to identify the type of memory requested by a client process to be mapped into its process space
IOAudioEngineState: Represents the state of an IOAudioEngine
IOAudioEngineStatus: Shared-memory structure giving audio engine status
IOAudioNotificationMessage: Used in the mach message for IOAudio notifications.
IOAudioSMPTETime: A structure for holding a SMPTE time.
IOAudioStreamDirection: Represents the direction of an IOAudioStream
SMPTETime: A structure for holding a SMPTE time.

IOAudioControlCalls

The set of constants passed to IOAudioControlUserClient::getExternalMethodForIndex() when making calls from the IOAudioFamily user client code.

typedef enum _IOAudioControlCalls { 
    kIOAudioControlCallSetValue = 0, 
    kIOAudioControlCallGetValue = 1 
} IOAudioControlCalls;

Constants

kIOAudioControlCallSetValue: Used to set the value of an IOAudioControl.
kIOAudioControlCallGetValue: Used to get the value of an IOAudioControl.

IOAudioControlNotifications

The set of constants passed in the type field of IOAudioControlUserClient::registerNotificaitonPort().

typedef enum _IOAudioControlNotifications { 
    kIOAudioControlValueChangeNotification = 0, 
    kIOAudioControlRangeChangeNotification = 1 
} IOAudioControlNotifications;

Constants

kIOAudioControlValueChangeNotification: Used to request value change notifications.
kIOAudioControlRangeChangeNotification: Used to request range change notifications.

IOAudioEngineCalls

The set of constants passed to IOAudioEngineUserClient::getExternalMethodForIndex() when making calls from the IOAudioFamily user client code.

typedef enum _IOAudioEngineCalls { 
    kIOAudioEngineCallRegisterClientBuffer = 0, 
    kIOAudioEngineCallUnregisterClientBuffer = 1, 
    kIOAudioEngineCallGetConnectionID = 2, 
    kIOAudioEngineCallStart = 3, 
    kIOAudioEngineCallStop = 4, 
    kIOAudioEngineCallGetNearestStartTime = 5 
} IOAudioEngineCalls;

IOAudioEngineMemory

Used to identify the type of memory requested by a client process to be mapped into its process space

typedef enum _IOAudioEngineMemory { 
    kIOAudioStatusBuffer = 0, 
    kIOAudioSampleBuffer = 1, 
    kIOAudioMixBuffer = 2, 
    kIOAudioBytesInInputBuffer = 3, 
    kIOAudioBytesInOutputBuffer = 4 
} IOAudioEngineMemory;

Constants

kIOAudioSampleBuffer: This requests the IOAudioEngine's sample buffer
kIOAudioStatusBuffer: This requests the IOAudioEngine's status buffer. It's type is IOAudioEngineStatus.
kIOAudioMixBuffer: This requests the IOAudioEngine's mix buffer

Discussion

This is the parameter to the type field of IOMapMemory when called on an IOAudioEngine. This is only intended for use by the Audio Device API library.

IOAudioEngineState

Represents the state of an IOAudioEngine

typedef enum _IOAudioEngineState { 
    kIOAudioEngineStopped = 0, 
    kIOAudioEngineRunning = 1, 
    kIOAudioEnginePaused = 2, 
    kIOAudioEngineResumed = 3 
} IOAudioEngineState;

Constants

kIOAudioEngineRunning: The IOAudioEngine is currently running - it is transferring data to or from the device.
kIOAudioEngineStopped: The IOAudioEngine is currently stopped - no activity is occurring.

IOAudioEngineStatus

Shared-memory structure giving audio engine status

typedef struct _IOAudioEngineStatus { 
    UInt32 fVersion; 
    volatile UInt32 fCurrentLoopCount; 
    volatile AbsoluteTime fLastLoopTime; 
    volatile UInt32 fEraseHeadSampleFrame; 
} IOAudioEngineStatus;

Fields

fVersion: Indicates version of this structure
fCurrentLoopCount: Number of times around the ring buffer since the audio engine started
fLastLoopTime: Timestamp of the last time the ring buffer wrapped
fEraseHeadSampleFrame: Location of the erase head in sample frames - erased up to but not including the given sample frame

IOAudioNotificationMessage

Used in the mach message for IOAudio notifications.

typedef struct _IOAudioNotificationMessage { 
    mach_msg_header_t messageHeader; 
    UInt32 type; 
    UInt32 ref; 
    void *sender; 
} IOAudioNotificationMessage;

Fields

messageHeader: Standard mach message header
ref: The param passed to registerNotificationPort() in refCon.

IOAudioSMPTETime

A structure for holding a SMPTE time.

See Also:

SMPTETime

typedef struct _IOAudioSMPTETime { 
    SInt16 fSubframes; 
    SInt16 fSubframeDivisor; 
    UInt32 fCounter; 
    UInt32 fType; 
    UInt32 fFlags; 
    SInt16 fHours; 
    SInt16 fMinutes; 
    SInt16 fSeconds; 
    SInt16 fFrames;  
} IOAudioSMPTETime;

Fields

fSubframes: The number of subframes in the full message.
fSubframeDivisor: The number of subframes per frame (typically 80).
fCounter: The total number of messages received.
fType: The kind of SMPTE time using the SMPTE time type constants.
fFlags: A set of flags that indicate the SMPTE state.
fHours: The number of hourse in the full message.
fMinutes: The number of minutes in the full message.
fSeconds: The number of seconds in the full message.
fFrames: The number of frames in the full message.

IOAudioStreamDirection

Represents the direction of an IOAudioStream

typedef enum _IOAudioStreamDirection { 
    kIOAudioStreamDirectionOutput = 0, 
    kIOAudioStreamDirectionInput = 1 
} IOAudioStreamDirection;

Constants

kAudioOutput: Output buffer
kAudioInput: Input buffer

SMPTETime

A structure for holding a SMPTE time.

See Also:

IOAudioSMPTETime

typedef struct _IOAudioSMPTETime { 
    SInt16 fSubframes; 
    SInt16 fSubframeDivisor; 
    UInt32 fCounter; 
    UInt32 fType; 
    UInt32 fFlags; 
    SInt16 fHours; 
    SInt16 fMinutes; 
    SInt16 fSeconds; 
    SInt16 fFrames;  
} IOAudioSMPTETime;

Fields

fSubframes: The number of subframes in the full message.
fSubframeDivisor: The number of subframes per frame (typically 80).
fCounter: The total number of messages received.
fType: The kind of SMPTE time using the SMPTE time type constants.
fFlags: A set of flags that indicate the SMPTE state.
fHours: The number of hourse in the full message.
fMinutes: The number of minutes in the full message.
fSeconds: The number of seconds in the full message.
fFrames: The number of frames in the full message.

Macro Definitions

kIOAudioControlNumCalls
kIOAudioEngineDefaultMixBufferSampleSize
kIOAudioEngineNumCalls

kIOAudioControlNumCalls

#define kIOAudioControlNumCalls 2

Discussion

The number of elements in the IOAudioControlCalls enum.

kIOAudioEngineDefaultMixBufferSampleSize

#define kIOAudioEngineDefaultMixBufferSampleSize sizeof(float)

kIOAudioEngineNumCalls

#define kIOAudioEngineNumCalls 6

Discussion

The number of elements in the IOAudioEngineCalls enum.

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Last Updated: 2009-10-15