Core Audio Data Types Reference

Framework	CoreAudio/CoreAudio.h
Declared in	CoreAudioTypes.h

Overview

This document describes data types and constants used throughout Core Audio, as well as some convenience functions for working with these types and constants.

If you are unfamiliar with the specialized terminology used when manipulating audio data, refer to Core Audio Glossary.

Functions by Task

Testing for Native Endian Linear PCM Data

Getting the Number of Channels From a Layout Tag

Helper Functions for Filling out Core Audio Data Structures

Functions

AudioChannelLayoutTag_GetNumberOfChannels

A macro to get the number of channels from an audio channel layout tag (AudioChannelLayoutTag data type).

#define AudioChannelLayoutTag_GetNumberOfChannels(layoutTag)
   ((UInt32)((layoutTag) & 0x0000FFFF))

Parameters

layoutTag: The audio channel layout tag to examine.

Return Value

The number of channels the tag indicates.

Discussion

The low 16 bits of an audio channel layout tag gives the number of channels, unless the layout tag is kAudioChannelLayoutTag_UseChannelDescriptions or kAudioChannelLayoutTag_UseChannelBitmap, which specify other ways of defining the layout.

Availability

Available in OS X v10.2 and later.

Related Sample Code

Declared In

CoreAudioTypes.h

CalculateLPCMFlags

A C++ inline function for calculating the value for the audio stream basic description mFormatFlags field for linear PCM data.

#if defined(__cplusplus)
inline UInt32 CalculateLPCMFlags (
   UInt32 inValidBitsPerChannel,
   UInt32 inTotalBitsPerChannel,
   bool inIsFloat,
   bool inIsBigEndian,
   bool inIsNonInterleaved = false
) {
   return
   (inIsFloat ? kAudioFormatFlagIsFloat : kAudioFormatFlagIsSignedInteger) |
   (inIsBigEndian ? ((UInt32)kAudioFormatFlagIsBigEndian) : 0)             |
   ((!inIsFloat && (inValidBitsPerChannel == inTotalBitsPerChannel)) ?
   kAudioFormatFlagIsPacked : kAudioFormatFlagIsAlignedHigh)           |
   (inIsNonInterleaved ? ((UInt32)kAudioFormatFlagIsNonInterleaved) : 0);
}
#endif

Parameters

inValidBitsPerChannel: The number of valid bits in each sample.
inTotalBitsPerChannel: The total number of bits in each sample.
inIsFloat: Use true if the samples are represented with floating point numbers.
inIsBigEndian: Use true if the samples are big endian.
inIsNonInterleaved: Use true if the samples are noninterleaved.

Return Value

A UInt32 value containing the calculated format flags.

Discussion

This function does not support specifying sample formats that are either unsigned integer or low-aligned.

Availability

Available in OS X v10.5 and later.

Declared In

CoreAudioTypes.h

FillOutASBDForLPCM

A C++ inline function for filling out an AudioStreamBasicDescription to describe linear PCM data.

#if defined(__cplusplus)
inline void FillOutASBDForLPCM (
   AudioStreamBasicDescription &outASBD,
   Float64 inSampleRate,
   UInt32 inChannelsPerFrame,
   UInt32 inValidBitsPerChannel,
   UInt32 inTotalBitsPerChannel,
   bool inIsFloat,
   bool inIsBigEndian,
   bool inIsNonInterleaved = false
) {
   outASBD.mSampleRate = inSampleRate;
   outASBD.mFormatID = kAudioFormatLinearPCM;
   outASBD.mFormatFlags =    CalculateLPCMFlags (
   inValidBitsPerChannel,
   inTotalBitsPerChannel,
   inIsFloat,
   inIsBigEndian,
   inIsNonInterleaved
   );
   outASBD.mBytesPerPacket =
   (inIsNonInterleaved ? 1 : inChannelsPerFrame) * (inTotalBitsPerChannel/8);
   outASBD.mFramesPerPacket = 1;
   outASBD.mBytesPerFrame =
   (inIsNonInterleaved ? 1 : inChannelsPerFrame) * (inTotalBitsPerChannel/8);
   outASBD.mChannelsPerFrame = inChannelsPerFrame;
   outASBD.mBitsPerChannel = inValidBitsPerChannel;
}
#endif

Parameters

outASBD: On output, a filled-out AudioStreamBasicDescription structure.
inSampleRate: The number of sample frames per second of the data in the stream.
inChannelsPerFrame: The number of channels in each frame of data.
inValidBitsPerChannel: The number of valid bits in each sample.
inTotalBitsPerChannel: The total number of bits in each sample.
inIsFloat: Use true if the samples are represented as floating-point numbers.
inIsBigEndian: Use true if the samples are big endian.
inIsNonInterleaved: Use true if the samples are noninterleaved.

Discussion

This function does not support specifying sample formats that are either unsigned integer or low-aligned.

Availability

Available in OS X v10.5 and later.

Declared In

CoreAudioTypes.h

FillOutAudioTimeStampWithHostTime

A C++ inline function for filling out an AudioTimeStamp structure with a host time.

#if defined(__cplusplus)
inline void FillOutAudioTimeStampWithHostTime (
   AudioTimeStamp &outATS,
   UInt64 inHostTime
) {
   outATS.mSampleTime = 0;
   outATS.mHostTime = inHostTime;
   outATS.mRateScalar = 0;
   outATS.mWordClockTime = 0;
   memset (&outATS.mSMPTETime, 0, sizeof (SMPTETime));
   outATS.mFlags = kAudioTimeStampHostTimeValid;
}
#endif

Parameters

outATS: On output, a filled-out AudioTimeStamp structure.
inHostTime: The host time to assign to the audio timestamp.

Availability

Available in OS X v10.5 and later.

Declared In

CoreAudioTypes.h

FillOutAudioTimeStampWithSampleAndHostTime

A C++ inline function for filling out an AudioTimeStamp structure with a sample time and a host time.

#if defined(__cplusplus)
inline void FillOutAudioTimeStampWithSampleAndHostTime (
   AudioTimeStamp &outATS,
   Float64 inSampleTime,
   UInt64 inHostTime
) {
   outATS.mSampleTime = inSampleTime;
   outATS.mHostTime = inHostTime;
   outATS.mRateScalar = 0;
   outATS.mWordClockTime = 0;
   memset (&outATS.mSMPTETime, 0, sizeof (SMPTETime));
   outATS.mFlags = kAudioTimeStampSampleTimeValid |
   kAudioTimeStampHostTimeValid;
}
#endif

Parameters

outATS: On output, a filled-out AudioTimeStamp structure.
inSampleTime: The sample time to assign to the audio timestamp.
inHostTime: The host time to assign to the audio timestamp.

Availability

Available in OS X v10.5 and later.

Declared In

CoreAudioTypes.h

FillOutAudioTimeStampWithSampleTime

A C++ inline function for filling out an AudioTimeStamp structure with a sample time.

#if defined(__cplusplus)
inline void FillOutAudioTimeStampWithSampleTime (
   AudioTimeStamp &outATS,
   Float64 inSampleTime
) {
   outATS.mSampleTime = inSampleTime;
   outATS.mHostTime = 0;
   outATS.mRateScalar = 0;
   outATS.mWordClockTime = 0;
   memset (&outATS.mSMPTETime, 0, sizeof (SMPTETime));
   outATS.mFlags = kAudioTimeStampSampleTimeValid;
}
#endif

Parameters

outATS: On output, a filled-out AudioTimeStamp structure.
inSampleTime: The sample time to assign to the audio timestamp.

Availability

Available in OS X v10.5 and later.

Declared In

CoreAudioTypes.h

IsAudioFormatNativeEndian

A C++ inline function for checking if an AudioFormatBasicDescription structure indicates native-endian linear PCM data.

#if defined(__cplusplus)
inline bool IsAudioFormatNativeEndian (
   const AudioStreamBasicDescription &f
) {
   return  (f.mFormatID == kAudioFormatLinearPCM) &&
   ((f.mFormatFlags & kAudioFormatFlagIsBigEndian) ==
   kAudioFormatFlagsNativeEndian);
}
#endif

Parameters

f: The AudioFormatBasicDescription structure you want to examine.

Return Value

A Boolean value indicating whether the AudioFormatBasicDescription structure specifies native endian linear PCM data, true if the data is linear PCM and is native endian.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

TestAudioFormatNativeEndian

A macro for checking if an AudioFormatBasicDescription structure indicates native endian linear PCM data.

#define TestAudioFormatNativeEndian (f)  (
   (f.mFormatID == kAudioFormatLinearPCM) &&
   ((f.mFormatFlags & kAudioFormatFlagIsBigEndian) ==
   kAudioFormatFlagsNativeEndian)
)

Parameters

f: The AudioFormatBasicDescription structure you want to examine.

Return Value

True if the data is linear PCM and is native endian.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

Data Types

AudioBuffer

Holds and describes a buffer of audio data.

struct AudioBuffer {
   UInt32 mNumberChannels;
   UInt32 mDataByteSize;
   void   *mData;
};
typedef struct AudioBuffer AudioBuffer;

Fields

mNumberChannels: The number of interleaved channels in the buffer. If the number is 1, the buffer is noninterleaved.
mDataByteSize: The number of bytes in the buffer pointed at by the mData field.
mData: A pointer to a buffer of audio data.

Discussion

An AudioBuffer structure holds a single buffer of audio data in its mData field. The buffer can represent two different sorts of audio:

A single, monophonic, noninterleaved channel of audio
Interleaved audio with any number of channels—as designated by the mNumberChannels field

Noninterleaved formats are used primarily by audio units and audio converters.

Availability

Available in OS X v10.0 and later.

Declared In

CoreAudioTypes.h

AudioBufferList

Holds a variable-length array of AudioBuffer structures.

struct AudioBufferList {
   UInt32      mNumberBuffers;
   AudioBuffer mBuffers[1];
};
typedef struct AudioBufferList AudioBufferList;

Fields

mNumberBuffers: The number of AudioBuffer structures in the mBuffers array.
mBuffers: A variable length array of AudioBuffer structures.

Discussion

The AudioBufferList structure provides a mechanism for encapsulating one or more buffers of audio data. It is used by functions in various Core Audio APIs, as described in Audio Converter Services Reference, Audio Unit Component Services Reference, and Extended Audio File Services Reference.

Availability

Available in OS X v10.0 and later.

Declared In

CoreAudioTypes.h

AudioChannelDescription

Describes an audio data channel.

struct AudioChannelDescription {
   AudioChannelLabel   mChannelLabel;
   UInt32              mChannelFlags;
   Float32             mCoordinates[3];
};
typedef struct AudioChannelDescription AudioChannelDescription;

Fields

mChannelLabel: The AudioChannelLabel structure that describes the channel.
mChannelFlags: Flags that control the interpretation of mCoordinates. See “Channel Coordinate Flags” for possible values.
mCoordinates: An ordered triple that specifies a precise speaker location. See “Channel Coordinate Index Constants” for the interpretation of the items in the array.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

AudioChannelLabel

Identifies how an audio data channel is to be used.

typedef UInt32 AudioChannelLabel;

Discussion

This data type is used for the mChannelLabel field of the AudioChannelDescription structure. See “Audio Channel Label Constants” for possible values.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

AudioChannelLayout

Specifies a channel layout in a file or in hardware.

struct AudioChannelLayout {
   AudioChannelLayoutTag     mChannelLayoutTag;
   UInt32                    mChannelBitmap;
   UInt32                    mNumberChannelDescriptions;
   AudioChannelDescription   mChannelDescriptions[1];
};
typedef struct AudioChannelLayout AudioChannelLayout;

Fields

mChannelLayoutTag: The AudioChannelLayoutTag value that indicates the layout. See “Audio Channel Layout Tags” for possible values.
mChannelBitmap: If mChannelLayoutTag is set to kAudioChannelLayoutTag_UseChannelBitmap, this field is the channel-use bitmap.
mNumberChannelDescriptions: The number of items in the mChannelDescriptions array.
mChannelDescriptions: A variable length array of mNumberChannelDescription elements that describes a layout. If the mChannelLayoutTag field is set to kAudioChannelLayoutTag_UseChannelDescriptions, use this field to describe the layout.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

AudioChannelLayoutTag

Identifies a previously-defined channel layout.

typedef UInt32 AudioChannelLayoutTag;

Discussion

This data type is used for the mChannelLayoutTag field of the AudioChannelLayout structure. See “Audio Channel Layout Tags” for possible values.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

AudioClassDescription

Describes an installed codec.

struct AudioClassDescription {
   OSType  mType;
   OSType  mSubType;
   OSType  mManufacturer;
};
typedef struct AudioClassDescription    AudioClassDescription;

Fields

mType: The four character code for the codec type. Defined by the codec manufacturer.
mSubType: The four character code for the codec subtype. Defined by the codec manufacturer.
mManufacturer: The four character code for the codec manufacturer. This must be a unique code registered with Apple.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

AudioSampleType

The canonical audio data sample type for input and output.

typedef SInt16 AudioSampleType;

Discussion

The canonical audio sample type for input and output in iPhone OS is linear PCM with 16-bit integer samples.

Availability

Available in OS X v10.5 and later.

Declared In

CoreAudioTypes.h

AudioUnitSampleType

The canonical audio data sample type for audio processing.

typedef SInt32 AudioUnitSampleType;
#define kAudioUnitSampleFractionBits 24

Discussion

The canonical audio sample type for audio units and other audio processing in iPhone OS is noninterleaved linear PCM with 8.24-bit fixed-point samples.

Availability

Available in OS X v10.6 and later.

Declared In

CoreAudioTypes.h

AudioStreamBasicDescription

An audio data format specification for a stream of audio.

struct AudioStreamBasicDescription {
   Float64 mSampleRate;
   UInt32  mFormatID;
   UInt32  mFormatFlags;
   UInt32  mBytesPerPacket;
   UInt32  mFramesPerPacket;
   UInt32  mBytesPerFrame;
   UInt32  mChannelsPerFrame;
   UInt32  mBitsPerChannel;
   UInt32  mReserved;
};
typedef struct AudioStreamBasicDescription  AudioStreamBasicDescription;

Fields

mSampleRate

The number of frames per second of the data in the stream, when the stream is played at normal speed. For compressed formats, this field indicates the number of frames per second of equivalent decompressed data.

The mSampleRate field must be nonzero, except when this structure is used in a listing of supported formats (see “kAudioStreamAnyRate”).

mFormatID

An identifier specifying the general audio data format in the stream. See “Audio Data Format Identifiers”. This value must be nonzero.

mFormatFlags

Format-specific flags to specify details of the format. May be set to 0 to indicate no format flags. See “Audio Data Format Identifiers” for the flags that apply to each format.

mBytesPerPacket

The number of bytes in a packet of audio data. To indicate variable packet size, set this field to 0. For a format that uses variable packet size, specify the size of each packet using an AudioStreamPacketDescription structure.

mFramesPerPacket

The number of frames in a packet of audio data. For uncompressed audio, the value is 1. For variable bit-rate formats, the value is a larger fixed number, such as 1024 for AAC. For formats with a variable number of frames per packet, such as Ogg Vorbis, set this field to 0.

mBytesPerFrame

The number of bytes from the start of one frame to the start of the next frame in an audio buffer. Set this field to 0 for compressed formats.

For an audio buffer containing interleaved data for n channels, with each sample of type AudioSampleType, calculate the value for this field as follows:

mBytesPerFrame = n * sizeof (AudioSampleType);

For an audio buffer containing noninterleaved (monophonic) data, also using AudioSampleType samples, calculate the value for this field as follows:

mBytesPerFrame = sizeof (AudioSampleType);

mChannelsPerFrame

The number of channels in each frame of audio data. This value must be nonzero.

mBitsPerChannel

The number of bits for one audio sample. For example, for linear PCM audio using the kAudioFormatFlagsCanonical format flags, calculate the value for this field as follows:

mBitsPerChannel = 8 * sizeof (AudioSampleType);

Set this field to 0 for compressed formats.

mReserved

Pads the structure out to force an even 8-byte alignment. Must be set to 0.

Discussion

You can configure an audio stream basic description (ASBD) to specify a linear PCM format or a constant bit rate (CBR) format that has channels of equal size. For variable bit rate (VBR) audio, and for CBR audio where the channels have unequal sizes, each packet must additionally be described by an AudioStreamPacketDescription structure.

A field value of 0 indicates that the value is either unknown or not applicable to the format.

Always initialize the fields of a new audio stream basic description structure to zero, as shown here:

AudioStreamBasicDescription myAudioDataFormat = {0};

To determine the duration represented by one packet, use the mSampleRate field with the mFramesPerPacket field, as follows:

duration = (1 / mSampleRate) * mFramesPerPacket

In Core Audio, the following definitions apply:

An audio stream is a continuous series of data that represents a sound, such as a song.
A channel is a discrete track of monophonic audio. A monophonic stream has one channel; a stereo stream has two channels.
A sample is single numerical value for a single audio channel in an audio stream.
A frame is a collection of time-coincident samples. For instance, a linear PCM stereo sound file has two samples per frame, one for the left channel and one for the right channel.
A packet is a collection of one or more contiguous frames. A packet defines the smallest meaningful set of frames for a given audio data format, and is the smallest data unit for which time can be measured. In linear PCM audio, a packet holds a single frame. In compressed formats, it typically holds more; in some formats, the number of frames per packet varies.
The sample rate for a stream is the number of frames per second of uncompressed (or, for compressed formats, the equivalent in decompressed) audio.

Availability

Available in OS X v10.0 and later.

Declared In

CoreAudioTypes.h

AudioStreamPacketDescription

Describes one packet in a buffer of audio data where the sizes of the packets differ or where there is non-audio data between audio packets.

struct AudioStreamPacketDescription {
   SInt64  mStartOffset;
   UInt32  mVariableFramesInPacket;
   UInt32  mDataByteSize;
};
typedef struct AudioStreamPacketDescription AudioStreamPacketDescription;

Fields

mStartOffset: The number of bytes from the start of the buffer to the beginning of the packet. For example, if the data buffer contains 5 bytes of data, with one byte per packet, then mStartOffset for the last packet is 4 (that is, there are 4 bytes in the buffer before the start of the last packet.
mVariableFramesInPacket: The number of sample frames of data in the packet. For formats with a constant number of frames per packet, this field is set to 0.
mDataByteSize: The number of bytes in the packet.

Discussion

For data formats where the packet size is not constant, such as variable bit rate data and data where the channels have unequal sizes, this structure is used to supplement the information in the AudioStreamBasicDescription structure.

Availability

Available in OS X v10.2 and later.

Declared In

CoreAudioTypes.h

AudioTimeStamp

Holds multiple representations of a time stamp.

struct AudioTimeStamp {
   Float64         mSampleTime;
   UInt64          mHostTime;
   Float64         mRateScalar;
   UInt64          mWordClockTime;
   SMPTETime       mSMPTETime;
   UInt32          mFlags;
   UInt32          mReserved;
};
typedef struct AudioTimeStamp AudioTimeStamp;

Fields

mSampleTime: The absolute sample frame time.
mHostTime: The host machine's time base (see CoreAudio/HostTime.h).
mRateScalar: The ratio of actual host ticks per sample frame to the nominal host ticks per sample frame.
mWordClockTime: The word clock time.
mSMPTETime: The SMPTE time (see SMPTETime).
mFlags: A set of flags indicating which representations of the time are valid; see “Audio Time Stamp Flags” and “Audio Time Stamp Flag Combination Constant”.
mReserved: Pads the structure out to force an even 8-byte alignment.

Availability

Available in OS X v10.0 and later.

Declared In

CoreAudioTypes.h

AudioValueRange

Holds a pair of numbers that represent a continuous range of values.

struct AudioValueRange {
   Float64 mMinimum;
   Float64 mMaximum;
};
typedef struct AudioValueRange AudioValueRange;

Fields

mMinimum: The minimum value.
mMaximum: The maximum value.

Availability

Available in OS X v10.1 and later.

Declared In

CoreAudioTypes.h

AudioValueTranslation

Holds buffers used in translation operations.

struct AudioValueTranslation {
   void*   mInputData;
   UInt32  mInputDataSize;
   void*   mOutputData;
   UInt32  mOutputDataSize;
};
typedef struct AudioValueTranslation AudioValueTranslation;

Fields

mInputData: The buffer containing the data to be translated.
mInputDataSize: The number of bytes in the buffer pointed at by mInputData.
mOutputData: The buffer to hold the result of the translation.
mOutputDataSize: The number of bytes in the buffer pointed at by mOutputData.

Availability

Available in OS X v10.1 and later.

Declared In

CoreAudioTypes.h

SMPTETime

Specifies a time stamp as one of the SMPTE time types.

struct SMPTETime {
   SInt16  mSubframes;
   SInt16  mSubframeDivisor;
   UInt32  mCounter;
   UInt32  mType;
   UInt32  mFlags;
   SInt16  mHours;
   SInt16  mMinutes;
   SInt16  mSeconds;
   SInt16  mFrames;
};
typedef struct SMPTETime SMPTETime;

Fields

mSubframes: A subframe offset to the HH:MM:SS:FF time. You can use this field to position a time marker somewhere within the time span represented by a video frame, if necessary.
mSubframeDivisor: The number of subframes per video frame (typically 80).
mCounter: The total number of messages received. It takes 8 messages to carry a full SMPTE time code.
mType: A SMPTE time type constant indicating the kind of SMPTE time used (see “SMPTE Timecode Type Constants”).
mFlags: A set of flags that indicate the SMPTE state (see “SMPTE State Flags”).
mHours: The value of the hours portion of the SMPTE time.
mMinutes: The value of the minutes portion of the SMPTE time.
mSeconds: The value of the seconds portion of the SMPTE time.
mFrames: The value of the frames portion of the SMPTE time.

Discussion

SMPTE (Society of Motion Picture and Television Engineers, pronounced “SIMPtee”) times are used to correlate a point in an audio stream with an external event. For example, a SMPTE time can be used to correlate a sound in an audio file with a video frame in a movie file.

Note that the frames referred to by this structure are video frames, where a video frame is a single complete image. (Compare with the definition of audio frames in the discussion for AudioStreamBasicDescription.)

A complete SMPTE time description takes 80 bits, including 32 user bits that contain vendor-specific information. The actual time-code portion of the SMPTE time description is normally sent in several messages, each message containing a portion of the time code. (The user bits are sent in a separate message.) Typically, the SMPTE time description is divided up into 8 1-byte messages, with the first nibble of each message specifying which portion of the time code is contained in the message and the second nibble containing the time information. Four such messages are normally sent with each video frame.

Video data contains somewhere from 24 to 60 frames per second (as specified by the SMPTE time type—see “SMPTE Timecode Type Constants”) and each video frame has an associated SMPTE time. SMPTE time is based on a 24-hour clock. Each frame’s SMPTE time consists of an hour, minute, and second value, plus the number of the frame within the second. Because audio data is sampled at a much higher rate (MP3 data is sampled at over 100,000 bits per second, for example), it is frequently desirable to correlate the audio data with a time within the persistence period of a single video frame. For this reason, the time period during which a single video frame is displayed is subdivided into subframes (typically 80 or 100 subframes per frame, as specified by the mSubFrameDivisor field). The mSubFrames field specifies the number of subframes into the video frame represented by this time structure.

Availability

Available in OS X v10.0 and later.

Declared In

CoreAudioTypes.h

Constants

kAudioStreamAnyRate

Indicates that an audio format can use any sample rate.

enum {
   kAudioStreamAnyRate = 0
};

Constants

kAudioStreamAnyRate

This constant can appear only in listings of supported formats. It can never be used as part of the description of an AudioStreamBasicDescription structure that is used for transporting or processing audio.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

Audio Data Format Identifiers

Identifiers for audio data formats, used in the AudioStreamBasicDescription structure.

enum {
   kAudioFormatLinearPCM               = 'lpcm',
   kAudioFormatAC3                     = 'ac-3',
   kAudioFormat60958AC3                = 'cac3',
   kAudioFormatAppleIMA4               = 'ima4',
   kAudioFormatMPEG4AAC                = 'aac ',
   kAudioFormatMPEG4CELP               = 'celp',
   kAudioFormatMPEG4HVXC               = 'hvxc',
   kAudioFormatMPEG4TwinVQ             = 'twvq',
   kAudioFormatMACE3                   = 'MAC3',
   kAudioFormatMACE6                   = 'MAC6',
   kAudioFormatULaw                    = 'ulaw',
   kAudioFormatALaw                    = 'alaw',
   kAudioFormatQDesign                 = 'QDMC',
   kAudioFormatQDesign2                = 'QDM2',
   kAudioFormatQUALCOMM                = 'Qclp',
   kAudioFormatMPEGLayer1              = '.mp1',
   kAudioFormatMPEGLayer2              = '.mp2',
   kAudioFormatMPEGLayer3              = '.mp3',
   kAudioFormatTimeCode                = 'time',
   kAudioFormatMIDIStream              = 'midi',
   kAudioFormatParameterValueStream    = 'apvs',
   kAudioFormatAppleLossless           = 'alac'
   kAudioFormatMPEG4AAC_HE             = 'aach',
   kAudioFormatMPEG4AAC_LD             = 'aacl',
   kAudioFormatMPEG4AAC_ELD            = 'aace',
   kAudioFormatMPEG4AAC_ELD_SBR        = 'aacf',
   kAudioFormatMPEG4AAC_HE_V2          = 'aacp',
   kAudioFormatMPEG4AAC_Spatial        = 'aacs',
   kAudioFormatAMR                     = 'samr',
   kAudioFormatAudible                 = 'AUDB',
   kAudioFormatiLBC                    = 'ilbc',
   kAudioFormatDVIIntelIMA             = 0x6D730011,
   kAudioFormatMicrosoftGSM            = 0x6D730031,
   kAudioFormatAES3                    = 'aes3'
};

Constants

kAudioFormatLinearPCM

A key that specifies linear PCM, a noncompressed audio data format with one frame per packet. Uses the linear PCM format flags in “AudioStreamBasicDescription Flags”.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kAudioFormatAC3

A key that specifies an AC-3 codec. Uses no flags.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormat60958AC3

A key that specifies an AC-3 codec that provides data packaged for transport over an IEC 60958 compliant digital audio interface. Uses the standard format flags in “AudioStreamBasicDescription Flags”.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatAppleIMA4

A key that specifies Apple’s implementation of the IMA 4:1 ADPCM codec. Uses no flags.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC

A key that specifies an MPEG-4 AAC codec. The flags field contains the MPEG-4 audio object type constant listed in “MPEG-4 Audio Object Type Constants” indicating the specific kind of data.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4CELP

A key that specifies an MPEG-4 CELP codec. The flags field contains the MPEG-4 audio object type constant listed in “MPEG-4 Audio Object Type Constants” indicating the specific kind of data.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4HVXC

A key that specifies an MPEG-4 HVXC codec. The flags field contains the MPEG-4 audio object type constant listed in “MPEG-4 Audio Object Type Constants” indicating the specific kind of data.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4TwinVQ

A key that specifies an MPEG-4 TwinVQ codec. The flags field contains the MPEG-4 audio object type constant listed in “MPEG-4 Audio Object Type Constants” indicating the specific kind of data.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMACE3

MACE 3:1. Uses no flags.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMACE6

MACE 6:1. Uses no flags.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatULaw

μLaw 2:1. Uses no flags.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatALaw

aLaw 2:1. Uses no flags.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatQDesign

QDesign music. Uses no flags

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatQDesign2

QDesign2 music. Uses no flags

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatQUALCOMM

QUALCOMM PureVoice. Uses no flags

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEGLayer1

MPEG-1/2, Layer 1 audio. Uses no flags

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEGLayer2

MPEG-1/2, Layer 2 audio. Uses no flags

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEGLayer3

MPEG-1/2, Layer 3 audio. Uses no flags

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatTimeCode

A stream of IOAudioTimeStamp structures. Uses the IOAudioTimeStamp flags (see “Audio Time Stamp Flags” and “Audio Time Stamp Flag Combination Constant”).

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMIDIStream

A stream of MIDIPacketList structures where the time stamps in the MIDIPacket structures are sample offsets in the stream. The mSampleRate field in the AudioStreamBasicDescription structure is used to describe how time is passed in this kind of stream and an audio unit that receives or generates this stream can use this sample rate together with the number of frames it is rendering and the sample offsets within the MIDIPacketList to define the time for any MIDI event within this list. Uses no flags.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatParameterValueStream

A "side-chain" of Float32 data that can be fed or generated by an audio unit and that is used to send a high density of parameter value control information. An audio unit typically runs a parameter value stream at either the sample rate of the audio unit’s audio data, or some integer quotient of this (say a half or a third of the sample rate of the audio). The mSampleRate field in the AudioStreamBasicDescription structure describes this relationship. Uses no flags.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatAppleLossless

Apple Lossless. Uses no flags.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC_HE

MPEG-4 High Efficiency AAC audio object. Uses no flags.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC_LD

MPEG-4 AAC Low Delay audio object. Uses no flags.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC_ELD

MPEG-4 AAC Enhanced Low Delay audio object. Uses no flags.

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC_ELD_SBR

MPEG-4 AAC Enhanced Low Delay audio object with SBR (spectral band replication) extension layer. Uses no flags.

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC_HE_V2

MPEG-4 High Efficiency AAC Version 2 audio object. Uses no flags.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMPEG4AAC_Spatial

MPEG-4 Spatial Audio audio object. Uses no flags.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioFormatAMR

The AMR (Adaptive Multi-Rate) narrow band speech codec.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioFormatAudible

The codec used for Audible, Inc. audio books. Uses no flags.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kAudioFormatiLBC

The iLBC (internet Low Bitrate Codec) narrow band speech codec. Uses no flags.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kAudioFormatDVIIntelIMA

DVI/Intel IMA ADPCM - ACM code 17.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kAudioFormatMicrosoftGSM

Microsoft GSM 6.10 - ACM code 49.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kAudioFormatAES3

The format defined by the AES3-2003 standard. Adopted into MXF and MPEG-2 containers and SDTI transport streams with SMPTE specs 302M-2002 and 331M-2000. Uses no flags.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

Discussion

Use these identifiers to test for the presence of audio codecs on a system. If a given codec is present, you can use its identifier to specify that codec for data encoding or decoding, according to the capabilities of the codec. For more information, see Core Audio Overview.

AudioStreamBasicDescription Flags

Standard flags for use in the mFormatFlags field of the AudioStreamBasicDescription structure.

enum {
   kAudioFormatFlagIsFloat                  = (1 << 0),    // 0x1
   kAudioFormatFlagIsBigEndian              = (1 << 1),    // 0x2
   kAudioFormatFlagIsSignedInteger          = (1 << 2),    // 0x4
   kAudioFormatFlagIsPacked                 = (1 << 3),    // 0x8
   kAudioFormatFlagIsAlignedHigh            = (1 << 4),    // 0x10
   kAudioFormatFlagIsNonInterleaved         = (1 << 5),    // 0x20
   kAudioFormatFlagIsNonMixable             = (1 << 6),    // 0x40
   kAudioFormatFlagsAreAllClear             = (1 << 31),
   
   kLinearPCMFormatFlagIsFloat              = kAudioFormatFlagIsFloat,
   kLinearPCMFormatFlagIsBigEndian          = kAudioFormatFlagIsBigEndian,
   kLinearPCMFormatFlagIsSignedInteger      = kAudioFormatFlagIsSignedInteger,
   kLinearPCMFormatFlagIsPacked             = kAudioFormatFlagIsPacked,
   kLinearPCMFormatFlagIsAlignedHigh        = kAudioFormatFlagIsAlignedHigh,
   kLinearPCMFormatFlagIsNonInterleaved     = kAudioFormatFlagIsNonInterleaved,
   kLinearPCMFormatFlagIsNonMixable         = kAudioFormatFlagIsNonMixable,
   kLinearPCMFormatFlagsSampleFractionShift = 7,
   kLinearPCMFormatFlagsSampleFractionMask  =
   (0x3F << kLinearPCMFormatFlagsSampleFractionShift),
   kLinearPCMFormatFlagsAreAllClear         = kAudioFormatFlagsAreAllClear,
   
   kAppleLosslessFormatFlag_16BitSourceData = 1,
   kAppleLosslessFormatFlag_20BitSourceData = 2,
   kAppleLosslessFormatFlag_24BitSourceData = 3,
   kAppleLosslessFormatFlag_32BitSourceData = 4
};

Constants

kAudioFormatFlagIsFloat

Set for floating point, clear for integer.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagIsBigEndian

Set for big endian, clear for little endian.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagIsSignedInteger

Set for signed integer, clear for unsigned integer. This is only valid if kAudioFormatFlagIsFloat is clear.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagIsPacked

Set if the sample bits occupy the entire available bits for the channel, clear if they are high- or low-aligned within the channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagIsAlignedHigh

Set if the sample bits are placed into the high bits of the channel, clear for low bit placement. This is only valid if kAudioFormatFlagIsPacked is clear.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagIsNonInterleaved

Set if the samples for each channel are located contiguously and the channels are laid out end to end, clear if the samples for each frame are laid out contiguously and the frames laid out end to end. This flag affects the use of the AudioStreamBasicDescription and AudioBufferList structures; see the discussion of the AudioStreamBasicDescription structure for details.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagIsNonMixable

Set to indicate when a format is nonmixable. Note that this flag is only used when interacting with the HAL's stream format information. It is not a valid flag for any other use.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagsSampleFractionShift

The linear PCM flags contain a 6-bit bitfield indicating that an integer format is to be interpreted as fixed point. The value indicates the number of bits are used to represent the fractional portion of each sample value. This constant indicates the bit position (counting from the right) of the bitfield in mFormatFlags field.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagsSampleFractionMask

<number_of_fractional_bits> = (mFormatFlags & kLinearPCMFormatFlagsSampleFractionMask) >> kLinearPCMFormatFlagsSampleFractionShift

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagsAreAllClear

Set to indicate all the flags are clear. You must use this constant instead of 0, because a 0 in the mFormatFlags field of the AudioStreamBasicDescription structure indicates that there are no format flags.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsFloat

Synonym for kAudioFormatFlagIsFloat.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsBigEndian

Synonym for kAudioFormatFlagIsBigEndian.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsSignedInteger

Synonym for kAudioFormatFlagIsSignedInteger.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsPacked

Synonym for kAudioFormatFlagIsPacked.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsAlignedHigh

Synonym for kAudioFormatFlagIsAlignedHigh.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsNonInterleaved

Synonym for kAudioFormatFlagIsNonInterleaved.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagIsNonMixable

Synonym for kAudioFormatFlagIsNonMixable.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kLinearPCMFormatFlagsAreAllClear

Synonym for kAudioFormatFlagsAreAllClear.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAppleLosslessFormatFlag_16BitSourceData

This flag is set for Apple Lossless data that was sourced from 16 bit native endian signed integer data.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAppleLosslessFormatFlag_20BitSourceData

Set for Apple Lossless data that was sourced from 20 bit native endian signed integer data aligned high in 24 bits.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAppleLosslessFormatFlag_24BitSourceData

Set for Apple Lossless data that was sourced from 24 bit native endian signed integer data.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAppleLosslessFormatFlag_32BitSourceData

Set for Apple Lossless data that was sourced from 32 bit native endian signed integer data.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

AudioStreamBasicDescription Flag Combinations Constants

Commonly used combinations of data format flags for the AudioStreamBasicDescription structure.

enum {
#if TARGET_RT_BIG_ENDIAN
   kAudioFormatFlagsNativeEndian       = kAudioFormatFlagIsBigEndian,
#else
   kAudioFormatFlagsNativeEndian       = 0,
#endif
   
#if !CA_PREFER_FIXED_POINT
   kAudioFormatFlagsCanonical          =   kAudioFormatFlagIsFloat |
   kAudioFormatFlagsNativeEndian |
   kAudioFormatFlagIsPacked,
   kAudioFormatFlagsAudioUnitCanonical =   kAudioFormatFlagIsFloat |
   kAudioFormatFlagsNativeEndian |
   kAudioFormatFlagIsPacked |
   kAudioFormatFlagIsNonInterleaved,
#else
   kAudioFormatFlagsCanonical          =   kAudioFormatFlagIsSignedInteger |
   kAudioFormatFlagsNativeEndian |
   kAudioFormatFlagIsPacked,
   kAudioFormatFlagsAudioUnitCanonical =   kAudioFormatFlagIsSignedInteger |
   kAudioFormatFlagsNativeEndian |
   kAudioFormatFlagIsPacked |
   kAudioFormatFlagIsNonInterleaved |
   (kAudioUnitSampleFractionBits <<
   kLinearPCMFormatFlagsSampleFractionShift),
   
#endif
   
   kAudioFormatFlagsNativeFloatPacked  =   kAudioFormatFlagIsFloat |
   kAudioFormatFlagsNativeEndian |
   kAudioFormatFlagIsPacked
};

Constants

kAudioFormatFlagsNativeEndian

Defined to set or clear kAudioFormatFlagIsBigEndian depending on the endianness of the processor at build time.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagsCanonical

The set of flags for the canonical input-output audio sample type, which match the AudioSampleType type.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagsAudioUnitCanonical

The flags for the canonical audio unit and processing sample type, which match the AudioUnitSampleType type.

Available in OS X v10.6 and later.

Declared in CoreAudioTypes.h.

kAudioFormatFlagsNativeFloatPacked

The flags for the canonical format of fully packed, native endian floating point data.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

Discussion

Fixed-point formats are preferred in iPhone OS, while floating-point formats are preferred in OS X.

MPEG-4 Audio Object Type Constants

Used in the mFormatFlags field of an AudioStreamBasicDescription structure that describes an MPEG-4 audio stream to specify the type of MPEG-4 audio data. (Deprecated. Deprecated in OS X v10.5.)

enum {
   kMPEG4Object_AAC_Main       = 1,
   kMPEG4Object_AAC_LC         = 2,
   kMPEG4Object_AAC_SSR        = 3,
   kMPEG4Object_AAC_LTP        = 4,
   kMPEG4Object_AAC_SBR        = 5,
   kMPEG4Object_AAC_Scalable   = 6,
   
   kMPEG4Object_TwinVQ         = 7,
   kMPEG4Object_CELP           = 8,
   kMPEG4Object_HVXC           = 9
   
};

Constants

kMPEG4Object_AAC_Main

Advanced audio coding; the basic MPEG-4 technology.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_AAC_LC

Lossless coding; provides compression with no loss of quality.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_AAC_SSR

Scalable sampling rate; provides different sampling frequencies for different targets.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_AAC_LTP

Long term prediction; reduces redundancy in a coded signal.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_AAC_SBR

Spectral band replication; reconstructs high-frequency content from lower frequencies and side information.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_AAC_Scalable

Scalable lossless coding.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_TwinVQ

Transform-domain weighted interleaved vector quantization, an audio codec optimized for audio coding at ultra low bit rates around 8 kbit/s.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_CELP

Code Excited Linear Prediction, a narrow-band/wide-band speech codec.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kMPEG4Object_HVXC

Harmonic Vector Excitation Coding, a very-low bit-rate parametric speech codec.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

Discussion

See the Moving Picture Experts Group web page (http://www.chiariglione.org/mpeg/) for details about MPEG technologies.

SMPTE Timecode Type Constants

SMPTE timecode types, used in the SMPTETime structure.

enum {
   kSMPTETimeType24        = 0,
   kSMPTETimeType25        = 1,
   kSMPTETimeType30Drop    = 2,
   kSMPTETimeType30        = 3,
   kSMPTETimeType2997      = 4,
   kSMPTETimeType2997Drop  = 5,
   kSMPTETimeType60        = 6,
   kSMPTETimeType5994      = 7,
   kSMPTETimeType60Drop    = 8,
   kSMPTETimeType5994Drop  = 9,
   kSMPTETimeType50        = 10,
   kSMPTETimeType2398      = 11
};

Constants

kSMPTETimeType24

24 video frames per second—standard for 16mm and 35mm film.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType25

25 video frames per second—standard for PAL and SECAM video.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType30Drop

30 video frames per second, with video-frame numbers adjusted to ensure that the timecode matches elapsed clock time.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType30

30 video frames per second.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType2997

29.97 video frames per second—standard for NTSC video.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType2997Drop

29.97 video frames per second, with video-frame numbers adjusted to ensure that the timecode matches elapsed clock time.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType60

60 video frames per second.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType5994

59.94 video frames per second.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType60Drop

60 video frames per second, with video-frame numbers adjusted to ensure that the timecode matches elapsed clock time.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType5994Drop

59.94 video frames per second, with video-frame numbers adjusted to ensure that the timecode matches elapsed clock time.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType50

50 video frames per second.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeType2398

23.98 video frames per second.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

SMPTE State Flags

Flags that describe a SMPTE time state.

enum {
   kSMPTETimeValid     = (1 << 0),
   kSMPTETimeRunning   = (1 << 1)
};

Constants

kSMPTETimeValid

The full time is valid.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kSMPTETimeRunning

Time is running.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

Audio Time Stamp Flags

These flags indicate the valid fields in an AudioTimeStamp structure.

enum {
   kAudioTimeStampSampleTimeValid      = (1 << 0),
   kAudioTimeStampHostTimeValid        = (1 << 1),
   kAudioTimeStampRateScalarValid      = (1 << 2),
   kAudioTimeStampWordClockTimeValid   = (1 << 3),
   kAudioTimeStampSMPTETimeValid       = (1 << 4)
};

Constants

kAudioTimeStampSampleTimeValid

The sample frame time is valid.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kAudioTimeStampHostTimeValid

The host time is valid.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kAudioTimeStampRateScalarValid

The rate scalar is valid.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kAudioTimeStampWordClockTimeValid

The word clock time is valid.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

kAudioTimeStampSMPTETimeValid

The SMPTE time is valid.

Available in OS X v10.0 and later.

Declared in CoreAudioTypes.h.

Audio Time Stamp Flag Combination Constant

A commonly used combination of audio time stamp flags.

enum {
   kAudioTimeStampSampleHostTimeValid  = (kAudioTimeStampSampleTimeValid | kAudioTimeStampHostTimeValid)
};

Constants

kAudioTimeStampSampleHostTimeValid

The sample frame time and the host time are valid.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

Audio Channel Label Constants

Channel labels for use in the mChannelLabel field of an AudioChannelDescription structure.

enum {
   kAudioChannelLabel_Unknown               = 0xFFFFFFFF,
   kAudioChannelLabel_Unused                = 0,
   kAudioChannelLabel_UseCoordinates        = 100,
   
   kAudioChannelLabel_Left                  = 1,
   kAudioChannelLabel_Right                 = 2,
   kAudioChannelLabel_Center                = 3,
   kAudioChannelLabel_LFEScreen             = 4,
   kAudioChannelLabel_LeftSurround          = 5,
   kAudioChannelLabel_RightSurround         = 6,
   kAudioChannelLabel_LeftCenter            = 7,
   kAudioChannelLabel_RightCenter           = 8,
   kAudioChannelLabel_CenterSurround        = 9,
   kAudioChannelLabel_LeftSurroundDirect    = 10,
   kAudioChannelLabel_RightSurroundDirect   = 11,
   kAudioChannelLabel_TopCenterSurround     = 12,
   kAudioChannelLabel_VerticalHeightLeft    = 13,
   kAudioChannelLabel_VerticalHeightCenter  = 14,
   kAudioChannelLabel_VerticalHeightRight   = 15,
   kAudioChannelLabel_TopBackLeft           = 16,
   kAudioChannelLabel_TopBackCenter         = 17,
   kAudioChannelLabel_TopBackRight          = 18,
   kAudioChannelLabel_RearSurroundLeft      = 33,
   kAudioChannelLabel_RearSurroundRight     = 34,
   kAudioChannelLabel_LeftWide              = 35,
   kAudioChannelLabel_RightWide             = 36,
   kAudioChannelLabel_LFE2                  = 37,
   kAudioChannelLabel_LeftTotal             = 38,
   kAudioChannelLabel_RightTotal            = 39,
   kAudioChannelLabel_HearingImpaired       = 40,
   kAudioChannelLabel_Narration             = 41,
   kAudioChannelLabel_Mono                  = 42,
   kAudioChannelLabel_DialogCentricMix      = 43,
   kAudioChannelLabel_CenterSurroundDirect  = 44,
   kAudioChannelLabel_Haptic                = 45,
   
   // first order ambisonic channels
   kAudioChannelLabel_Ambisonic_W           = 200,
   kAudioChannelLabel_Ambisonic_X           = 201,
   kAudioChannelLabel_Ambisonic_Y           = 202,
   kAudioChannelLabel_Ambisonic_Z           = 203,
   
   // Mid/Side Recording
   kAudioChannelLabel_MS_Mid                = 204,
   kAudioChannelLabel_MS_Side               = 205,
   
   // X-Y Recording
   kAudioChannelLabel_XY_X                  = 206,
   kAudioChannelLabel_XY_Y                  = 207,
   
   // other
   kAudioChannelLabel_HeadphonesLeft        = 301,
   kAudioChannelLabel_HeadphonesRight       = 302,
   kAudioChannelLabel_ClickTrack            = 304,
   kAudioChannelLabel_ForeignLanguage       = 305,
   
   // generic discrete channel
   kAudioChannelLabel_Discrete              = 400,
   
   // numbered discrete channel
   kAudioChannelLabel_Discrete_0            = (1<<16) | 0,
   kAudioChannelLabel_Discrete_1            = (1<<16) | 1,
   kAudioChannelLabel_Discrete_2            = (1<<16) | 2,
   kAudioChannelLabel_Discrete_3            = (1<<16) | 3,
   kAudioChannelLabel_Discrete_4            = (1<<16) | 4,
   kAudioChannelLabel_Discrete_5            = (1<<16) | 5,
   kAudioChannelLabel_Discrete_6            = (1<<16) | 6,
   kAudioChannelLabel_Discrete_7            = (1<<16) | 7,
   kAudioChannelLabel_Discrete_8            = (1<<16) | 8,
   kAudioChannelLabel_Discrete_9            = (1<<16) | 9,
   kAudioChannelLabel_Discrete_10           = (1<<16) | 10,
   kAudioChannelLabel_Discrete_11           = (1<<16) | 11,
   kAudioChannelLabel_Discrete_12           = (1<<16) | 12,
   kAudioChannelLabel_Discrete_13           = (1<<16) | 13,
   kAudioChannelLabel_Discrete_14           = (1<<16) | 14,
   kAudioChannelLabel_Discrete_15           = (1<<16) | 15,
   kAudioChannelLabel_Discrete_65535        = (1<<16) | 65535
};

Constants

kAudioChannelLabel_Unknown

Unknown role or unspecified other use for channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Unused

The channel is present, but has no intended role or destination.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_UseCoordinates

The channel is described solely by the mCoordinates field of the AudioChannelDescription structure.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Left

Left channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Right

Right channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Center

Center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LFEScreen

Low Frequency Effects Screen; a subwoofer located in front of the theater.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LeftSurround

Left surround channel; or for WAVE (.wav) files, back left.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RightSurround

Right surround channel; or for WAVE (.wav) files, back right.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LeftCenter

Left center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RightCenter

Right center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_CenterSurround

Center surround channel; or for WAVE (.wav) files, back center or rear surround.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LeftSurroundDirect

Left surround direct channel; or for WAVE (.wav) files, side left.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RightSurroundDirect

Right surround direct channel; or for WAVE (.wav) files, side right.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_TopCenterSurround

Top center surround-sound channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_VerticalHeightLeft

Vertical height left channel; or for WAVE (.wav) files, top front left.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_VerticalHeightCenter

Vertical height center channel; or for WAVE (.wav) files, top front center.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_VerticalHeightRight

Vertical height right channel; or for WAVE (.wav) files, top front right.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_TopBackLeft

Top back left channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_TopBackCenter

Top back center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_TopBackRight

Top back right channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RearSurroundLeft

Rear surround left channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RearSurroundRight

Rear surround right channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LeftWide

Left wide channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RightWide

Right wide channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LFE2

Low Frequency Effects 2.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_LeftTotal

The left channel of matrix encoded 4 channel audio.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_RightTotal

The right channel of matrix encoded 4 channel audio.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_HearingImpaired

Channel carrying audio for the hearing impaired.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Narration

Narration channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Mono

Monaural channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_DialogCentricMix

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_CenterSurroundDirect

Back center, non diffuse channel.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Haptic

A channel for haptic (touch) data.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Ambisonic_W

First order Ambisonic channel W.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Ambisonic_X

First order Ambisonic channel X.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Ambisonic_Y

First order Ambisonic channel Y.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Ambisonic_Z

First order Ambisonic channel Z.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_MS_Mid

Mid channel of a Mid/Side recording.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_MS_Side

Side channel of a Mid/Side recording.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_XY_X

X channel of an X-Y recording.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_XY_Y

Y channel of an X-Y recording.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_HeadphonesLeft

Left channel of stereo headphones.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_HeadphonesRight

Right channel of stereo headphones.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_ClickTrack

Click track channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_ForeignLanguage

Foreign language channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete

Generic discrete channel.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_0

Discrete channel 0.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_1

Discrete channel 1.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_2

Discrete channel 2.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_3

Discrete channel 3.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_4

Discrete channel 4.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_5

Discrete channel 5.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_6

Discrete channel 6.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_7

Discrete channel 7.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_8

Discrete channel 8.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_9

Discrete channel 9.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_10

Discrete channel 10.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_11

Discrete channel 11.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_12

Discrete channel 12.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_13

Discrete channel 13.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_14

Discrete channel 14.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_15

Discrete channel 15.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLabel_Discrete_65535

Discrete channel 65536.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

Channel Bitmap Constants

Channel bits for use in the mChannelBitmap field of an AudioChannelLayout structure.

enum {
   kAudioChannelBit_Left                       = (1<<0),
   kAudioChannelBit_Right                      = (1<<1),
   kAudioChannelBit_Center                     = (1<<2),
   kAudioChannelBit_LFEScreen                  = (1<<3),
   kAudioChannelBit_LeftSurround               = (1<<4),
   kAudioChannelBit_RightSurround              = (1<<5),
   kAudioChannelBit_LeftCenter                 = (1<<6),
   kAudioChannelBit_RightCenter                = (1<<7),
   kAudioChannelBit_CenterSurround             = (1<<8),
   kAudioChannelBit_LeftSurroundDirect         = (1<<9),
   kAudioChannelBit_RightSurroundDirect        = (1<<10),
   kAudioChannelBit_TopCenterSurround          = (1<<11),
   kAudioChannelBit_VerticalHeightLeft         = (1<<12),
   kAudioChannelBit_VerticalHeightCenter       = (1<<13),
   kAudioChannelBit_VerticalHeightRight        = (1<<14),
   kAudioChannelBit_TopBackLeft                = (1<<15),
   kAudioChannelBit_TopBackCenter              = (1<<16),
   kAudioChannelBit_TopBackRight               = (1<<17)
};

Constants

kAudioChannelBit_Left

Left channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_Right

Right channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_Center

Center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_LFEScreen

Low Frequency Effects screen channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_LeftSurround

Left surround channel; or for WAVE (.wav) files, back left.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_RightSurround

RIght surround channel; or for WAVE (.wav) files, back right.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_LeftCenter

Left center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_RightCenter

Right center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_CenterSurround

Center surround channel; or for WAVE (.wav) files, back center.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_LeftSurroundDirect

Left surround direct channel; or for WAVE (.wav) files, side left.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_RightSurroundDirect

Right surround direct channel; or for WAVE (.wav) files, side right.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_TopCenterSurround

To center surround channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_VerticalHeightLeft

Vertical height left channel; or for WAVE (.wav) files, top front left.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_VerticalHeightCenter

Vertical height center channel; or for WAVE (.wav) files, top front center.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_VerticalHeightRight

Vertical height right channel; or for WAVE (.wav) files, top front right.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_TopBackLeft

Top back left channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_TopBackCenter

Top back center channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelBit_TopBackRight

Top back right channel.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

Channel Coordinate Flags

Used in the mChannelFlags field of an AudioChannelDescription structure.

enum {
   kAudioChannelFlags_AllOff                    = 0,
   kAudioChannelFlags_RectangularCoordinates   = (1<<0),
   kAudioChannelFlags_SphericalCoordinates     = (1<<1),
   kAudioChannelFlags_Meters                   = (1<<2)
};

Constants

kAudioChannelFlags_AllOff

All flags are clear.

Available in OS X v10.4 and later.

Declared in CoreAudioTypes.h.

kAudioChannelFlags_RectangularCoordinates

Set to indicate the channel is specified by the Cartesian coordinates of the speaker position. This flag is mutually exclusive with kAudioChannelFlags_SphericalCoordinates.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelFlags_SphericalCoordinates

Set to indicate the channel is specified by the spherical coordinates of the speaker position. This flag is mutually exclusive with kAudioChannelFlags_RectangularCoordinates.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelFlags_Meters

Set to indicate the units are in meters, clear to indicate the units are relative to the unit cube or unit sphere. For relative units, the listener is assumed to be at the center of the cube or sphere and the radius of the sphere or the distance from the center to the midpoint of the side of the cube is 1.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

Channel Coordinate Index Constants

Indexes the fields of the mCoordinates array in an AudioChannelDescription structure.

enum {
   kAudioChannelCoordinates_LeftRight  = 0,
   kAudioChannelCoordinates_BackFront  = 1,
   kAudioChannelCoordinates_DownUp     = 2,
   kAudioChannelCoordinates_Azimuth    = 0,
   kAudioChannelCoordinates_Elevation  = 1,
   kAudioChannelCoordinates_Distance   = 2
};

Constants

kAudioChannelCoordinates_LeftRight

For rectangular coordinates, negative is left and positive is right. The units are specified by the mChannelFlags field of the AudioChannelDescription structure.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelCoordinates_BackFront

For rectangular coordinates, negative is back and positive is front. The units are specified by the mChannelFlags field.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelCoordinates_DownUp

For rectangular coordinates, negative is below ground level, 0 is ground level, and positive is above ground level. The units are specified by the mChannelFlags field.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelCoordinates_Azimuth

For spherical coordinates, 0 is front center, positive is right, negative is left, and measurements are in degrees.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelCoordinates_Elevation

For spherical coordinates, +90 is zenith, 0 is horizontal, -90 is nadir, and measurements are in degrees.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelCoordinates_Distance

For spherical coordinates, distance is radially from the center. The units are specified by the mChannelFlags field of the AudioChannelDescription structure.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

Audio Channel Layout Tags

Identifiers for audio channel layouts. These identifiers specify the channels included in a layout but do not specify a particular ordering of those channels. Used in the mChannelLayoutTag field of an AudioChannelLayout structure.

enum {
   kAudioChannelLayoutTag_UseChannelDescriptions  = (0<<16) | 0,
   kAudioChannelLayoutTag_UseChannelBitmap        = (1<<16) | 0,
   
   //  General layouts
   kAudioChannelLayoutTag_Mono                    = (100<<16) | 1,
   kAudioChannelLayoutTag_Stereo                  = (101<<16) | 2,
   kAudioChannelLayoutTag_StereoHeadphones        = (102<<16) | 2,
   kAudioChannelLayoutTag_MatrixStereo            = (103<<16) | 2,
   kAudioChannelLayoutTag_MidSide                 = (104<<16) | 2,
   kAudioChannelLayoutTag_XY                      = (105<<16) | 2,
   kAudioChannelLayoutTag_Binaural                = (106<<16) | 2,
   kAudioChannelLayoutTag_Ambisonic_B_Format      = (107<<16) | 4,
   kAudioChannelLayoutTag_Quadraphonic            = (108<<16) | 4,
   kAudioChannelLayoutTag_Pentagonal              = (109<<16) | 5,
   kAudioChannelLayoutTag_Hexagonal               = (110<<16) | 6,
   kAudioChannelLayoutTag_Octagonal               = (111<<16) | 8,
   kAudioChannelLayoutTag_Cube                    = (112<<16) | 8,
   
   //  MPEG defined layouts
   kAudioChannelLayoutTag_MPEG_1_0                = kAudioChannelLayoutTag_Mono,
   kAudioChannelLayoutTag_MPEG_2_0                = kAudioChannelLayoutTag_Stereo,
   kAudioChannelLayoutTag_MPEG_3_0_A              = (113<<16) | 3,
   kAudioChannelLayoutTag_MPEG_3_0_B              = (114<<16) | 3,
   kAudioChannelLayoutTag_MPEG_4_0_A              = (115<<16) | 4,
   kAudioChannelLayoutTag_MPEG_4_0_B              = (116<<16) | 4,
   kAudioChannelLayoutTag_MPEG_5_0_A              = (117<<16) | 5,
   kAudioChannelLayoutTag_MPEG_5_0_B              = (118<<16) | 5,
   kAudioChannelLayoutTag_MPEG_5_0_C              = (119<<16) | 5,
   kAudioChannelLayoutTag_MPEG_5_0_D              = (120<<16) | 5,
   kAudioChannelLayoutTag_MPEG_5_1_A              = (121<<16) | 6,
   kAudioChannelLayoutTag_MPEG_5_1_B              = (122<<16) | 6,
   kAudioChannelLayoutTag_MPEG_5_1_C              = (123<<16) | 6,
   kAudioChannelLayoutTag_MPEG_5_1_D              = (124<<16) | 6,
   kAudioChannelLayoutTag_MPEG_6_1_A              = (125<<16) | 7,
   kAudioChannelLayoutTag_MPEG_7_1_A              = (126<<16) | 8,
   kAudioChannelLayoutTag_MPEG_7_1_B              = (127<<16) | 8,
   kAudioChannelLayoutTag_MPEG_7_1_C              = (128<<16) | 8,
   kAudioChannelLayoutTag_Emagic_Default_7_1      = (129<<16) | 8,
   kAudioChannelLayoutTag_SMPTE_DTV               = (130<<16) | 8,
   
   //  ITU defined layouts
   kAudioChannelLayoutTag_ITU_1_0                 = kAudioChannelLayoutTag_Mono,
   kAudioChannelLayoutTag_ITU_2_0                 = kAudioChannelLayoutTag_Stereo,
   kAudioChannelLayoutTag_ITU_2_1                 = (131<<16) | 3,
   kAudioChannelLayoutTag_ITU_2_2                 = (132<<16) | 4,
   kAudioChannelLayoutTag_ITU_3_0                 =
   kAudioChannelLayoutTag_MPEG_3_0_A,
   kAudioChannelLayoutTag_ITU_3_1                 =
   kAudioChannelLayoutTag_MPEG_4_0_A,
   kAudioChannelLayoutTag_ITU_3_2                 =
   kAudioChannelLayoutTag_MPEG_5_0_A,
   kAudioChannelLayoutTag_ITU_3_2_1               =
   kAudioChannelLayoutTag_MPEG_5_1_A,
   kAudioChannelLayoutTag_ITU_3_4_1               =
   kAudioChannelLayoutTag_MPEG_7_1_C,
   
   // DVD defined layouts
   kAudioChannelLayoutTag_DVD_0                   = kAudioChannelLayoutTag_Mono,
   kAudioChannelLayoutTag_DVD_1                   = kAudioChannelLayoutTag_Stereo,
   kAudioChannelLayoutTag_DVD_2                   = kAudioChannelLayoutTag_ITU_2_1,
   kAudioChannelLayoutTag_DVD_3                   = kAudioChannelLayoutTag_ITU_2_2,
   kAudioChannelLayoutTag_DVD_4                   = (133<<16) | 3,
   kAudioChannelLayoutTag_DVD_5                   = (134<<16) | 4,
   kAudioChannelLayoutTag_DVD_6                   = (135<<16) | 5,
   kAudioChannelLayoutTag_DVD_7                   =
   kAudioChannelLayoutTag_MPEG_3_0_A,
   kAudioChannelLayoutTag_DVD_8                   =
   kAudioChannelLayoutTag_MPEG_4_0_A,
   kAudioChannelLayoutTag_DVD_9                   =
   kAudioChannelLayoutTag_MPEG_5_0_A,
   kAudioChannelLayoutTag_DVD_10                  = (136<<16) | 4,
   kAudioChannelLayoutTag_DVD_11                  = (137<<16) | 5,
   kAudioChannelLayoutTag_DVD_12                  =
   kAudioChannelLayoutTag_MPEG_5_1_A,
   kAudioChannelLayoutTag_DVD_13                  = kAudioChannelLayoutTag_DVD_8,
   kAudioChannelLayoutTag_DVD_14                  = kAudioChannelLayoutTag_DVD_9,
   kAudioChannelLayoutTag_DVD_15                  = kAudioChannelLayoutTag_DVD_10,
   kAudioChannelLayoutTag_DVD_16                  = kAudioChannelLayoutTag_DVD_11,
   kAudioChannelLayoutTag_DVD_17                  = kAudioChannelLayoutTag_DVD_12,
   kAudioChannelLayoutTag_DVD_18                  = (138<<16) | 5,
   kAudioChannelLayoutTag_DVD_19                  =
   kAudioChannelLayoutTag_MPEG_5_0_B,
   kAudioChannelLayoutTag_DVD_20                  =
   kAudioChannelLayoutTag_MPEG_5_1_B,
   
   // These layouts are recommended for AudioUnit use;
   // these are the symmetrical layouts
   kAudioChannelLayoutTag_AudioUnit_4             =
   kAudioChannelLayoutTag_Quadraphonic,
   kAudioChannelLayoutTag_AudioUnit_5             =
   kAudioChannelLayoutTag_Pentagonal,
   kAudioChannelLayoutTag_AudioUnit_6             =
   kAudioChannelLayoutTag_Hexagonal,
   kAudioChannelLayoutTag_AudioUnit_8             =
   kAudioChannelLayoutTag_Octagonal,
   // These are the surround-based layouts
   kAudioChannelLayoutTag_AudioUnit_5_0           =
   kAudioChannelLayoutTag_MPEG_5_0_B,
   kAudioChannelLayoutTag_AudioUnit_6_0           = (139<<16) | 6,
   kAudioChannelLayoutTag_AudioUnit_7_0           = (140<<16) | 7,
   kAudioChannelLayoutTag_AudioUnit_7_0_Front     = (148<<16) | 7,
   kAudioChannelLayoutTag_AudioUnit_5_1           =
   kAudioChannelLayoutTag_MPEG_5_1_A,
   kAudioChannelLayoutTag_AudioUnit_6_1           =
   kAudioChannelLayoutTag_MPEG_6_1_A,
   kAudioChannelLayoutTag_AudioUnit_7_1           =
   kAudioChannelLayoutTag_MPEG_7_1_C,
   kAudioChannelLayoutTag_AudioUnit_7_1_Front     =
   kAudioChannelLayoutTag_MPEG_7_1_A,
   
   kAudioChannelLayoutTag_AAC_3_0                 =
   kAudioChannelLayoutTag_MPEG_3_0_B,
   kAudioChannelLayoutTag_AAC_Quadraphonic        =
   kAudioChannelLayoutTag_Quadraphonic,
   kAudioChannelLayoutTag_AAC_4_0                 =
   kAudioChannelLayoutTag_MPEG_4_0_B,
   kAudioChannelLayoutTag_AAC_5_0                 =
   kAudioChannelLayoutTag_MPEG_5_0_D,
   kAudioChannelLayoutTag_AAC_5_1                 =
   kAudioChannelLayoutTag_MPEG_5_1_D,
   kAudioChannelLayoutTag_AAC_6_0                 = (141<<16) | 6,
   kAudioChannelLayoutTag_AAC_6_1                 = (142<<16) | 7,
   kAudioChannelLayoutTag_AAC_7_0                 = (143<<16) | 7,
   kAudioChannelLayoutTag_AAC_7_1                 =
   kAudioChannelLayoutTag_MPEG_7_1_B,
   kAudioChannelLayoutTag_AAC_Octagonal           = (144<<16) | 8,
   
   kAudioChannelLayoutTag_TMH_10_2_std            = (145<<16) | 16,
   kAudioChannelLayoutTag_TMH_10_2_full           = (146<<16) | 21,
   
   kAudioChannelLayoutTag_AC3_1_0_1               = (149<<16) | 2,
   kAudioChannelLayoutTag_AC3_3_0                 = (150<<16) | 3,
   kAudioChannelLayoutTag_AC3_3_1                 = (151<<16) | 4,
   kAudioChannelLayoutTag_AC3_3_0_1               = (152<<16) | 4,
   kAudioChannelLayoutTag_AC3_2_1_1               = (153<<16) | 4,
   kAudioChannelLayoutTag_AC3_3_1_1               = (154<<16) | 5,
   
   kAudioChannelLayoutTag_EAC_6_0_A               = (155<<16) | 6,
   kAudioChannelLayoutTag_EAC_7_0_A               = (156<<16) | 7,
   kAudioChannelLayoutTag_EAC3_6_1_A              = (157<<16) | 7,
   kAudioChannelLayoutTag_EAC3_6_1_B              = (158<<16) | 7,
   kAudioChannelLayoutTag_EAC3_6_1_C              = (159<<16) | 7,
   kAudioChannelLayoutTag_EAC3_7_1_A              = (160<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_B              = (161<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_C              = (162<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_D              = (163<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_E              = (164<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_F              = (165<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_G              = (166<<16) | 8,
   kAudioChannelLayoutTag_EAC3_7_1_H              = (167<<16) | 8,
   
   kAudioChannelLayoutTag_DTS_3_1                 = (168<<16) | 4,
   kAudioChannelLayoutTag_DTS_4_1                 = (169<<16) | 5,
   kAudioChannelLayoutTag_DTS_6_0_A               = (170<<16) | 6,
   kAudioChannelLayoutTag_DTS_6_0_B               = (171<<16) | 6,
   kAudioChannelLayoutTag_DTS_6_0_C               = (172<<16) | 6,
   kAudioChannelLayoutTag_DTS_6_1_A               = (173<<16) | 7,
   kAudioChannelLayoutTag_DTS_6_1_B               = (174<<16) | 7,
   kAudioChannelLayoutTag_DTS_6_1_C               = (175<<16) | 7,
   kAudioChannelLayoutTag_DTS_6_1_D               = (182<<16) | 7,
   kAudioChannelLayoutTag_DTS_7_0                 = (176<<16) | 7,
   kAudioChannelLayoutTag_DTS_7_1                 = (177<<16) | 8,
   kAudioChannelLayoutTag_DTS_8_0_A               = (178<<16) | 8,
   kAudioChannelLayoutTag_DTS_8_0_B               = (179<<16) | 8,
   kAudioChannelLayoutTag_DTS_8_1_A               = (180<<16) | 9,
   kAudioChannelLayoutTag_DTS_8_1_B               = (181<<16) | 9,
   
   kAudioChannelLayoutTag_DiscreteInOrder         = (147<<16) | 0
   kAudioChannelLayoutTag_Unknown                 = 0xFFFF0000
};

Constants

kAudioChannelLayoutTag_UseChannelDescriptions

Use the array of AudioChannelDescription structures to define the layout.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_UseChannelBitmap

Use the bitmap to define the layout.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Mono

A standard monophonic stream.

Monophonic signal

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Stereo

A standard stereophonic stream; playback implied.

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_StereoHeadphones

A standard stereo stream; headphone playback implied.

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MatrixStereo

A matrix-encoded stereo stream.

Left matrix total

Right matrix total

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MidSide

Mid/side recording.

Center

Sides

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_XY

Coincident, angled microphone pair.

X (left)

Y (right)

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Binaural

Binaural stereo.

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Ambisonic_B_Format

Ambisonic B-format.

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Quadraphonic

Quadraphonic, with 90° loudspeaker separation.

Left front

Right front

Left back

Right back

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Pentagonal

Pentagonal, with 72° loudspeaker separation.

Left

Right

Left rear

Right rear

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Hexagonal

Hexagonal, with 60° loudspeaker separation.

Left

Right

Left rear

Right rear

Front center

Rear center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Octagonal

Octagonal, with 45° loudspeaker separation.

Left front

Right front

Left rear

Right rear

Center front

Center rear

Left side

Right side

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Cube

Cubic.

Left front

Right front

Left rear

Right rear

Left front top

Right front top

Left rear top

Right rear top

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_1_0

MPEG 1-channel.

Monophonic signal

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_2_0

MPEG 2-channel.

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_3_0_A

MPEG 3-channel layout A.

Left

Right

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_3_0_B

MPEG 3-channel layout B.

Center

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_4_0_A

MPEG 4- channel layout A.

Left

Right

Center

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_4_0_B

MPEG 4-channel layout B.

Center

Left

Right

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_0_A

MPEG 5-channel layout A.

Left

Right

Center

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_0_B

MPEG 5-channel layout B.

Left

Right

Left surround

Right surround

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_0_C

MPEG 5-channel layout C.

Left

Center

Right

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_0_D

MPEG 5-channel layout D.

Center

Left

Right

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_1_A

MPEG 5.1-channel layout A.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_1_B

MPEG 5.1-channel layout B.

Left

Right

Left surround

Right surround

Center

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_1_C

MPEG 5.1-channel layout C.

Left

Center

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_5_1_D

MPEG 5.1-channel layout D.

Center

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_6_1_A

MPEG 6.1-channel layout A.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_7_1_A

MPEG 7.1-channel layout A.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Left center

Right center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_7_1_B

MPEG 7.1-channel layout A (see ISO/IEC 13818-7 MPEG2-AAC, Table 3.1).

Center

Left center

Right center

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_MPEG_7_1_C

MPEG 7.1-channel layout C.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Left rear surround

Right rear surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Emagic_Default_7_1

Emagic 7.1-channel default layout.

Left

Right

Left surround

Right surround

Center

Low-frequency effects

Left center

Right center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_SMPTE_DTV

SMPTE DTV layout; equivalent to the kAudioChannelLayoutTag_ITU_5_1 layout plus a matrix encoded stereo mix.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Left matrix total

Right matrix total

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_1_0

ITU 1-channel layout.

Monophonic signal

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_2_0

ITU 2-channel layout.

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_2_1

ITU 2.1-channel layout.

Left

Right

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_2_2

ITU 2.2-channel layout.

Left

Right

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_3_0

ITU 3-channel layout.

Left

Right

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_3_1

ITU 3.1-channel layout.

Left

Right

Center

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_3_2

ITU 3.2-channel layout.

Left

Right

Center

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_3_2_1

ITU 3.2.1-channel layout.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_ITU_3_4_1

ITU 3.4.1-channel layout.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Left rear surround

Right rear surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_0

DVD monaural layout.

Monophonic signal

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_1

DVD stereo layout.

Left

Right

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_2

DVD 3-channel layout.

Left

Right

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_3

DVD 4-channel layout.

Left

Right

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_4

DVD 2.1-channel layout.

Left

Right

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_5

DVD 3.1-channel layout.

Left

Right

Low-frequency effects

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_6

DVD 4.1-channel layout.

Left

Right

Low-frequency effects

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_7

DVD 3-channel layout.

Left

Right

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_8

DVD 4-channel layout.

Left

Right

Center

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_9

DVD 5-channel layout.

Left

Right

Center

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_10

DVD 3.1-channel layout.

Left

Right

Center

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_11

DVD 4.1-channel layout.

Left

Right

Center

Low-frequency effects

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_12

DVD 5.1-channel layout.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_13

DVD 4-channel layout; equivalent to kAudioChannelLayoutTag_DVD_8.

Left

Right

Center

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_14

DVD 5-channel layout; equivalent to kAudioChannelLayoutTag_DVD_9.

Left

Right

Center

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_15

DVD 3.1-channel layout; equivalent to kAudioChannelLayoutTag_DVD_10.

Left

Right

Center

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_16

DVD 4.1-channel layout; equivalent to kAudioChannelLayoutTag_DVD_11.

Left

Right

Center

Low-frequency effects

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_17

DVD 5.1-channel layout; equivalent to kAudioChannelLayoutTag_DVD_12.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_18

DVD 4.1-channel layout.

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_19

DVD 5-channel layout.

Left

Right

Left surround

Right surround

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DVD_20

DVD 5.1-channel layout.

Left

Right

Left surround

Right surround

Center

Low-frequency effects

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_4

Quadraphonic symmetrical layout, recommended for use by audio units.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_5

Pentagonal symmetrical layout, recommended for use by audio units.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_6

Hexagonal symmetrical layout, recommended for use by audio units.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_8

Octagonal symmetrical layout, recommended for use by audio units.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_5_0

5-channel surround-based layout, recommended for use by audio units.

Left

Right

Left surround

Right surround

Center

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_6_0

6-channel surround-based layout, recommended for use by audio units.

Left

Right

Left surround

Right surround

Center

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_7_0

7-channel surround-based layout, recommended for use by audio units.

Left

Right

Left surround

Right surround

Center

Left rear surround

Right rear surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_7_0_Front

Alternate 7-channel surround-based layout, for use by audio units.

Left

Right

Left surround

Right surround

Center

Left center

Right center

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_5_1

5.1-channel surround-based layout, recommended for use by audio units.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_6_1

6.1-channel surround-based layout, recommended for use by audio units.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Center surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_7_1

7.1-channel surround-based layout, recommended for use by audio units.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Left rear surround

Right rear surround

Available in OS X v10.2 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AudioUnit_7_1_Front

7.1-channel surround-based layout, recommended for use by audio units.

Left

Right

Center

Low-frequency effects

Left surround

Right surround

Left center

Right center

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_3_0

AAC 3-channel surround-based layout.

Center

Left

Right

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_Quadraphonic

AAC quadraphonic surround-based layout.

Left

Right

Left surround

Right surround

Left surround

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_4_0

AAC 4-channel surround-based layout.

Center

Left

Right

Center surround

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_5_0

AAC 5-channel surround-based layout.

Center

Left

Right

Left surround

Right surround

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_5_1

AAC 5.1-channel surround-based layout.

Center

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_6_0

AAC 6-channel surround-based layout.

Center

Left

Right

Left surround

Right surround

Center surround

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_6_1

AAC 6.1-channel surround-based layout.

Center

Left

Right

Left surround

Right surround

Center surround

Low-frequency effects

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_7_0

AAC 7-channel surround-based layout.

Center

Left

Right

Left surround

Right surround

Left rear surround

Right rear surround

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_7_1

AAC 7.1-channel surround-based layout.

Center

Left center

Right center

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AAC_Octagonal

AAC 8-channel surround-based layout.

Center

Left

Right

Left surround

Right surround

Left rear surround

Right rear surround

Center surround

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_TMH_10_2_std

TMH 10.2, a multiple-channel surround-based layout .

This table contains more than one row to accommodate the page width. There is no relationship between items in the same column.

Left	Right	Center	Vertical height center	Left surround direct	Right surround direct	Left surround	Right surround
Vertical height left	Vertical height right	Left wide	Right wide	Center surround direct	Center surround	Low-frequency effects 1	Low-frequency effects 2

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_TMH_10_2_full

TMH 10.2 (kAudioChannelLayoutTag_TMH_10_2_std) plus additional channels; recommended for use by audio units.

This table contains more than one row to accommodate the page width. There is no relationship between items in the same column.

Left	Right	Center	Vertical height center	Left surround direct	Right surround direct	Left surround	Right surround
Vertical height left	Vertical height right	Left wide	Right wide	Center surround direct	Center surround	Low-frequency effects 1	Low-frequency effects 2
Left center	Right center	HI	VI	Haptic

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AC3_1_0_1

An AC-3 layout.

Center

Low-frequency effects

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AC3_3_0

An AC-3 layout.

Left

Center

Right

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AC3_3_1

An AC-3 layout.

Left

Center

Right

Center surround

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AC3_3_0_1

An AC-3 layout.

Left

Center

Right

Low-frequency effects

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AC3_2_1_1

An AC-3 layout.

Left

Right

Center surround

Low-frequency effects

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_AC3_3_1_1

An AC-3 layout.

Left

Center

Right

Center Surround

Low-frequency Effects

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC_6_0_A

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Center Surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC_7_0_A

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Left rear surround

Right rear surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_6_1_A

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Center surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_6_1_B

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Top surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_6_1_C

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Vertical height center

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_A

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Left rear surround

Right rear surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_B

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Left center

Right center

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_C

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Left surround direct

Right surround direct

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_D

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Left wide

Right wide

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_E

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Vertical height left

Vertical height right

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_F

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Center surround

Top surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_G

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Center surround

Vertical height center

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_EAC3_7_1_H

A Blu-ray Disc audio layout for Enhanced AC-3, also known as Dolby Digital Plus.

Left

Center

Right

Left Surround

Right Surround

Low-frequency effects

Top surround

Vertical height center

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_3_1

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Left

Right

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_4_1

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Left

Right

Center surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_0_A

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Right center

Left

Right

Left surround

Right surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_0_B

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Left

Right

Left rear surround

Right rear surround

Top surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_0_C

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Center surround

Left

Right

Left rear surround

Right rear surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_1_A

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Right center

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_1_B

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Left

Right

Left rear surround

Right rear surround

Top surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_1_C

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Center surround

Left

Right

Left rear surround

Right rear surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_6_1_D

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Center

Left

Right

Left surround

Right surround

Low-frequency effects

Center surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_7_0

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Center

Right center

Left

Right

Left surround

Right surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_7_1

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Center

Right center

Left

Right

Left surround

Right surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_8_0_A

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Right center

Left

Right

Left surround

Right surround

Left rear surround

Right rear surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_8_0_B

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Center

Right

Left

Right

Left surround

Center surround

Right surround

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_8_1_A

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Right center

Left

Right

Left surround

Right surround

Left rear surround

Right rear surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DTS_8_1_B

A Blu-ray Disc audio layout, defined by DTS (Digital Theater Systems Ltd.).

Left center

Center

Right center

Left

Right

Left surround

Center surround

Right surround

Low-frequency effects

Available in OS X v10.7 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_DiscreteInOrder

Needs to be ORed with the actual number of channels.

Available in OS X v10.3 and later.

Declared in CoreAudioTypes.h.

kAudioChannelLayoutTag_Unknown

Needs to be ORed with the actual number of channels.

Available in OS X v10.5 and later.

Declared in CoreAudioTypes.h.

Result Codes

This table lists result codes returned from the various C-based audio frameworks.

Result Code	Value	Description
`kAudio_UnimplementedError`	-4	An unimplemented system function was called. Available in OS X v10.7 and later.
`kAudio_FileNotFoundError`	-43	The file was not found. Available in OS X v10.7 and later.
`kAudio_ParamError`	-50	An error in the parameter list of the function. Available in OS X v10.7 and later.
`kAudio_MemFullError`	-108	Not enough room in the heap zone. Available in OS X v10.7 and later.

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