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ADC Home > Reference Library > Reference > Audio > Core Audio > Core Audio Framework Reference
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CoreAudioTypes |
| Includes: | <TargetConditionals.h> <CoreServices/../Frameworks/CarbonCore.framework/Headers/MacTypes.h> <MacTypes.h> |
This header defines the types and constants that all the CoreAudio APIs have in common.
IsAudioFormatNativeEndian |
A C++ inline function for checking if an ASBD indicates native endian linear PCM data.
inline bool IsAudioFormatNativeEndian( const AudioStreamBasicDescription& f)
fWhether or not the ASBD indicates native endian linear PCM data.
AudioChannelLabel |
A tag idenitfying how the channel is to be used.
typedef UInt32 AudioChannelLabel;
AudioChannelLayoutTag |
A tag identifying a particular pre-defined channel layout.
typedef UInt32 AudioChannelLayoutTag;
AudioBuffer |
A structure to hold a buffer of audio data.
struct AudioBuffer { UInt32 mNumberChannels; UInt32 mDataByteSize; void*mData; };
mNumberChannels- The number of interleaved channels in the buffer.
mDataByteSize- The number of bytes in the buffer pointed at by mData.
mData- A pointer to the buffer of audio data.
AudioBufferList |
A variable length array of AudioBuffer structures.
struct AudioBufferList { UInt32 mNumberBuffers; AudioBuffer mBuffers[kVariableLengthArray]; };
mNumberBuffers- The number of AudioBuffers in the mBuffers array.
mBuffers- A variable length array of AudioBuffers.
AudioChannelDescription |
This structure describes a single channel.
struct AudioChannelDescription { AudioChannelLabel mChannelLabel; UInt32 mChannelFlags; Float32 mCoordinates[3]; };
mChannelLabel- The AudioChannelLabel that describes the channel.
mChannelFlags- Flags that control the interpretation of mCoordinates.
mCoordinates- An ordered triple that specifies a precise speaker location.
AudioChannelLayout |
This structure is used to specify channel layouts in files and hardware.
struct AudioChannelLayout { AudioChannelLayoutTag mChannelLayoutTag; UInt32 mChannelBitmap; UInt32 mNumberChannelDescriptions; AudioChannelDescription mChannelDescriptions[ kVariableLengthArray]; };
mChannelLayoutTag- The AudioChannelLayoutTag that indicates the layout.
mChannelBitmap- If mChannelLayoutTag is set to kAudioChannelLayoutTag_UseChannelBitmap, this field is the channel usage bitmap.
mNumberChannelDescriptions- The number of items in the mChannelDescriptions array.
mChannelDescriptions- A variable length array of AudioChannelDescriptions that describe the layout.
AudioClassDescription |
This structure is used to describe codecs installed on the system.
struct AudioClassDescription { OSType mType; OSType mSubType; OSType mManufacturer; };
mType- The four char code codec type.
mSubType- The four char code codec subtype.
mManufacturer- The four char code codec manufacturer.
AudioStreamBasicDescription |
This structure encapsulates all the information for describing the basic format properties of a stream of audio data.
struct AudioStreamBasicDescription { Float64 mSampleRate; UInt32 mFormatID; UInt32 mFormatFlags; UInt32 mBytesPerPacket; UInt32 mFramesPerPacket; UInt32 mBytesPerFrame; UInt32 mChannelsPerFrame; UInt32 mBitsPerChannel; UInt32 mReserved; };
mSampleRate- The number of sample frames per second of the data in the stream.
mFormatID- A four char code indicating the general kind of data in the stream.
mFormatFlags- Flags specific to each format.
mBytesPerPacket- The number of bytes in a packet of data.
mFramesPerPacket- The number of sample frames in each packet of data.
mBytesPerFrame- The number of bytes in a single sample frame of data.
mChannelsPerFrame- The number of channels in each frame of data.
mBitsPerChannel- The number of bits of sample data for each channel in a frame of data.
mReserved- Pads the structure out to force an even 8 byte alignment.
This structure is sufficient to describe any constant bit rate format that has
channels that are the same size. Extensions are required for variable bit rate
data and for constant bit rate data where the channels have unequal sizes.
However, where applicable, the appropriate fields will be filled out correctly
for these kinds of formats (the extra data is provided via separate properties).
In all fields, a value of 0 indicates that the field is either unknown, not
applicable or otherwise is inapproprate for the format and should be ignored.
Note that 0 is still a valid value for most formats in the mFormatFlags field.
In audio data a frame is one sample across all channels. In non-interleaved
audio, the per frame fields identify one channel. In interleaved audio, the per
frame fields identify the set of n channels. In uncompressed audio, a Packet is
one frame, (mFramesPerPacket == 1). In compressed audio, a Packet is an
indivisible chunk of compressed data, for example an AAC packet will contain
1024 sample frames.
AudioStreamPacketDescription |
This structure describes the packet layout of a buffer of data where the size of each packet may not be the same or where there is extraneous data between packets.
struct AudioStreamPacketDescription { SInt64 mStartOffset; UInt32 mVariableFramesInPacket; UInt32 mDataByteSize; };
mStartOffset- The number of bytes from the start of the buffer to the beginning of the 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.
AudioTimeStamp |
A strucutre that holds different representations of the same point in time.
struct AudioTimeStamp { Float64 mSampleTime; UInt64 mHostTime; Float64 mRateScalar; UInt64 mWordClockTime; SMPTETime mSMPTETime; UInt32 mFlags; UInt32 mReserved; };
mSampleTime- The absolute sample frame time.
mHostTime- The host machine's time base (see
). 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.
mFlags- A set of flags indicating which representations of the time are valid.
mReserved- Pads the structure out to force an even 8 byte alignment.
AudioValueRange |
This structure holds a pair of numbers that represent a continuous range of values.
struct AudioValueRange { Float64 mMinimum; Float64 mMaximum; };
mMinimum- The minimum value.
mMaximum- The maximum value.
AudioValueTranslation |
This stucture holds the buffers necessary for translation operations.
struct AudioValueTranslation { void*mInputData; UInt32 mInputDataSize; void*mOutputData; UInt32 mOutputDataSize; };
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.
SMPTETime |
A structure for holding a SMPTE time.
struct SMPTETime { SInt16 mSubframes; SInt16 mSubframeDivisor; UInt32 mCounter; UInt32 mType; UInt32 mFlags; SInt16 mHours; SInt16 mMinutes; SInt16 mSeconds; SInt16 mFrames; };
mSubframes- The number of subframes in the full message.
mSubframeDivisor- The number of subframes per frame (typically 80).
mCounter- The total number of messages received.
mType- The kind of SMPTE time using the SMPTE time type constants.
mFlags- A set of flags that indicate the SMPTE state.
mHours- The number of hourse in the full message.
mMinutes- The number of minutes in the full message.
mSeconds- The number of seconds in the full message.
mFrames- The number of frames in the full message.
AudioChannelLabel Constants |
These constants are for use in the mChannelLabel field of an AudioChannelDescription structure.
enum { kAudioChannelLabel_Unknown = 0xFFFFFFFF, // unknown or unspecified other use kAudioChannelLabel_Unused = 0, // channel is present, but has no intended use or destination kAudioChannelLabel_UseCoordinates = 100, // channel is described by the mCoordinates fields. kAudioChannelLabel_Left = 1, kAudioChannelLabel_Right = 2, kAudioChannelLabel_Center = 3, kAudioChannelLabel_LFEScreen = 4, kAudioChannelLabel_LeftSurround = 5, // WAVE: "Back Left" kAudioChannelLabel_RightSurround = 6, // WAVE: "Back Right" kAudioChannelLabel_LeftCenter = 7, kAudioChannelLabel_RightCenter = 8, kAudioChannelLabel_CenterSurround = 9, // WAVE: "Back Center" or plain "Rear Surround" kAudioChannelLabel_LeftSurroundDirect = 10, // WAVE: "Side Left" kAudioChannelLabel_RightSurroundDirect = 11, // WAVE: "Side Right" kAudioChannelLabel_TopCenterSurround = 12, kAudioChannelLabel_VerticalHeightLeft = 13, // WAVE: "Top Front Left" kAudioChannelLabel_VerticalHeightCenter = 14, // WAVE: "Top Front Center" kAudioChannelLabel_VerticalHeightRight = 15, // WAVE: "Top Front Right" 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, // matrix encoded 4 channels kAudioChannelLabel_RightTotal = 39, // matrix encoded 4 channels kAudioChannelLabel_HearingImpaired = 40, kAudioChannelLabel_Narration = 41, kAudioChannelLabel_Mono = 42, kAudioChannelLabel_DialogCentricMix = 43, kAudioChannelLabel_CenterSurroundDirect = 44, // back center, non diffuse // 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 = ( 1L<<16) | 0, kAudioChannelLabel_Discrete_1 = ( 1L<<16) | 1, kAudioChannelLabel_Discrete_2 = ( 1L<<16) | 2, kAudioChannelLabel_Discrete_3 = ( 1L<<16) | 3, kAudioChannelLabel_Discrete_4 = ( 1L<<16) | 4, kAudioChannelLabel_Discrete_5 = ( 1L<<16) | 5, kAudioChannelLabel_Discrete_6 = ( 1L<<16) | 6, kAudioChannelLabel_Discrete_7 = ( 1L<<16) | 7, kAudioChannelLabel_Discrete_8 = ( 1L<<16) | 8, kAudioChannelLabel_Discrete_9 = ( 1L<<16) | 9, kAudioChannelLabel_Discrete_10 = ( 1L<<16) | 10, kAudioChannelLabel_Discrete_11 = ( 1L<<16) | 11, kAudioChannelLabel_Discrete_12 = ( 1L<<16) | 12, kAudioChannelLabel_Discrete_13 = ( 1L<<16) | 13, kAudioChannelLabel_Discrete_14 = ( 1L<<16) | 14, kAudioChannelLabel_Discrete_15 = ( 1L<<16) | 15, kAudioChannelLabel_Discrete_65535 = ( 1L<<16) | 65535 };
These channel labels attempt to list all labels in common use. Due to the
ambiguities in channel labeling by various groups, there may be some overlap or
duplication in the labels below. Use the label which most clearly describes what
you mean.
WAVE files seem to follow the USB spec for the channel flags. A channel map lets
you put these channels in any order, however a WAVE file only supports labels
1-18 and if present, they must be in the order given below. The integer values
for the labels below match the bit position of the label in the USB bitmap and
thus also the WAVE file bitmap.
AudioChannelLayoutTag |
These constants are used in the mChannelLayoutTag field of an AudioChannelLayout structure.
enum { // Some channel abbreviations used below: // L - left // R - right // C - center // Ls - left surround // Rs - right surround // Cs - center surround // Rls - rear left surround // Rrs - rear right surround // Lw - left wide // Rw - right wide // Lsd - left surround direct // Rsd - right surround direct // Lc - left center // Rc - right center // Ts - top surround // Vhl - vertical height left // Vhc - vertical height center // Vhr - vertical height right // Lt - left matrix total. for matrix encoded stereo. // Rt - right matrix total. for matrix encoded stereo. // General layouts kAudioChannelLayoutTag_UseChannelDescriptions = ( 0L<<16) | 0, // use the array of AudioChannelDescriptions to define the mapping. kAudioChannelLayoutTag_UseChannelBitmap = ( 1L<<16) | 0, // use the bitmap to define the mapping. kAudioChannelLayoutTag_Mono = ( 100L<<16) | 1, // a standard mono stream kAudioChannelLayoutTag_Stereo = ( 101L<<16) | 2, // a standard stereo stream (L R) - implied playback kAudioChannelLayoutTag_StereoHeadphones = ( 102L<<16) | 2, // a standard stereo stream (L R) - implied headphone playbac kAudioChannelLayoutTag_MatrixStereo = ( 103L<<16) | 2, // a matrix encoded stereo stream (Lt, Rt) kAudioChannelLayoutTag_MidSide = ( 104L<<16) | 2, // mid/side recording kAudioChannelLayoutTag_XY = ( 105L<<16) | 2, // coincident mic pair (often 2 figure 8's) kAudioChannelLayoutTag_Binaural = ( 106L<<16) | 2, // binaural stereo (left, right) kAudioChannelLayoutTag_Ambisonic_B_Format = ( 107L<<16) | 4, // W, X, Y, Z kAudioChannelLayoutTag_Quadraphonic = ( 108L<<16) | 4, // front left, front right, back left, back right kAudioChannelLayoutTag_Pentagonal = ( 109L<<16) | 5, // left, right, rear left, rear right, center kAudioChannelLayoutTag_Hexagonal = ( 110L<<16) | 6, // left, right, rear left, rear right, center, rear kAudioChannelLayoutTag_Octagonal = ( 111L<<16) | 8, // front left, front right, rear left, rear right, // front center, rear center, side left, side right kAudioChannelLayoutTag_Cube = ( 112L<<16) | 8, // left, right, rear left, rear right // top left, top right, top rear left, top rear right // MPEG defined layouts kAudioChannelLayoutTag_MPEG_1_0 = kAudioChannelLayoutTag_Mono, // C kAudioChannelLayoutTag_MPEG_2_0 = kAudioChannelLayoutTag_Stereo, // L R kAudioChannelLayoutTag_MPEG_3_0_A = ( 113L<<16) | 3, // L R C kAudioChannelLayoutTag_MPEG_3_0_B = ( 114L<<16) | 3, // C L R kAudioChannelLayoutTag_MPEG_4_0_A = ( 115L<<16) | 4, // L R C Cs kAudioChannelLayoutTag_MPEG_4_0_B = ( 116L<<16) | 4, // C L R Cs kAudioChannelLayoutTag_MPEG_5_0_A = ( 117L<<16) | 5, // L R C Ls Rs kAudioChannelLayoutTag_MPEG_5_0_B = ( 118L<<16) | 5, // L R Ls Rs C kAudioChannelLayoutTag_MPEG_5_0_C = ( 119L<<16) | 5, // L C R Ls Rs kAudioChannelLayoutTag_MPEG_5_0_D = ( 120L<<16) | 5, // C L R Ls Rs kAudioChannelLayoutTag_MPEG_5_1_A = ( 121L<<16) | 6, // L R C LFE Ls Rs kAudioChannelLayoutTag_MPEG_5_1_B = ( 122L<<16) | 6, // L R Ls Rs C LFE kAudioChannelLayoutTag_MPEG_5_1_C = ( 123L<<16) | 6, // L C R Ls Rs LFE kAudioChannelLayoutTag_MPEG_5_1_D = ( 124L<<16) | 6, // C L R Ls Rs LFE kAudioChannelLayoutTag_MPEG_6_1_A = ( 125L<<16) | 7, // L R C LFE Ls Rs Cs kAudioChannelLayoutTag_MPEG_7_1_A = ( 126L<<16) | 8, // L R C LFE Ls Rs Lc Rc kAudioChannelLayoutTag_MPEG_7_1_B = ( 127L<<16) | 8, // C Lc Rc L R Ls Rs LFE (doc: IS-13818-7 MPEG2-AAC Table 3.1) kAudioChannelLayoutTag_MPEG_7_1_C = ( 128L<<16) | 8, // L R C LFE Ls R Rls Rrs kAudioChannelLayoutTag_Emagic_Default_7_1 = ( 129L<<16) | 8, // L R Ls Rs C LFE Lc Rc kAudioChannelLayoutTag_SMPTE_DTV = ( 130L<<16) | 8, // L R C LFE Ls Rs Lt Rt // (kAudioChannelLayoutTag_ITU_5_1 plus a matrix encoded stereo mix) // ITU defined layouts kAudioChannelLayoutTag_ITU_1_0 = kAudioChannelLayoutTag_Mono, // C kAudioChannelLayoutTag_ITU_2_0 = kAudioChannelLayoutTag_Stereo, // L R kAudioChannelLayoutTag_ITU_2_1 = ( 131L<<16) | 3, // L R Cs kAudioChannelLayoutTag_ITU_2_2 = ( 132L<<16) | 4, // L R Ls Rs kAudioChannelLayoutTag_ITU_3_0 = kAudioChannelLayoutTag_MPEG_3_0_A, // L R C kAudioChannelLayoutTag_ITU_3_1 = kAudioChannelLayoutTag_MPEG_4_0_A, // L R C Cs kAudioChannelLayoutTag_ITU_3_2 = kAudioChannelLayoutTag_MPEG_5_0_A, // L R C Ls Rs kAudioChannelLayoutTag_ITU_3_2_1 = kAudioChannelLayoutTag_MPEG_5_1_A, // L R C LFE Ls Rs kAudioChannelLayoutTag_ITU_3_4_1 = kAudioChannelLayoutTag_MPEG_7_1_C, // L R C LFE Ls Rs Rls Rrs // DVD defined layouts kAudioChannelLayoutTag_DVD_0 = kAudioChannelLayoutTag_Mono, // C (mono) kAudioChannelLayoutTag_DVD_1 = kAudioChannelLayoutTag_Stereo, // L R kAudioChannelLayoutTag_DVD_2 = kAudioChannelLayoutTag_ITU_2_1, // L R Cs kAudioChannelLayoutTag_DVD_3 = kAudioChannelLayoutTag_ITU_2_2, // L R Ls Rs kAudioChannelLayoutTag_DVD_4 = ( 133L<<16) | 3, // L R LFE kAudioChannelLayoutTag_DVD_5 = ( 134L<<16) | 4, // L R LFE Cs kAudioChannelLayoutTag_DVD_6 = ( 135L<<16) | 5, // L R LFE Ls Rs kAudioChannelLayoutTag_DVD_7 = kAudioChannelLayoutTag_MPEG_3_0_A, // L R C kAudioChannelLayoutTag_DVD_8 = kAudioChannelLayoutTag_MPEG_4_0_A, // L R C Cs kAudioChannelLayoutTag_DVD_9 = kAudioChannelLayoutTag_MPEG_5_0_A, // L R C Ls Rs kAudioChannelLayoutTag_DVD_10 = ( 136L<<16) | 4, // L R C LFE kAudioChannelLayoutTag_DVD_11 = ( 137L<<16) | 5, // L R C LFE Cs kAudioChannelLayoutTag_DVD_12 = kAudioChannelLayoutTag_MPEG_5_1_A, // L R C LFE Ls Rs // 13 through 17 are duplicates of 8 through 12. kAudioChannelLayoutTag_DVD_13 = kAudioChannelLayoutTag_DVD_8, // L R C Cs kAudioChannelLayoutTag_DVD_14 = kAudioChannelLayoutTag_DVD_9, // L R C Ls Rs kAudioChannelLayoutTag_DVD_15 = kAudioChannelLayoutTag_DVD_10, // L R C LFE kAudioChannelLayoutTag_DVD_16 = kAudioChannelLayoutTag_DVD_11, // L R C LFE Cs kAudioChannelLayoutTag_DVD_17 = kAudioChannelLayoutTag_DVD_12, // L R C LFE Ls Rs kAudioChannelLayoutTag_DVD_18 = ( 138L<<16) | 5, // L R Ls Rs LFE kAudioChannelLayoutTag_DVD_19 = kAudioChannelLayoutTag_MPEG_5_0_B, // L R Ls Rs C kAudioChannelLayoutTag_DVD_20 = kAudioChannelLayoutTag_MPEG_5_1_B, // L R Ls Rs C LFE // These layouts are recommended for AudioUnit usage // 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, // L R Ls Rs C kAudioChannelLayoutTag_AudioUnit_6_0 = ( 139L<<16) | 6, // L R Ls Rs C Cs kAudioChannelLayoutTag_AudioUnit_7_0 = ( 140L<<16) | 7, // L R Ls Rs C Rls Rrs kAudioChannelLayoutTag_AudioUnit_5_1 = kAudioChannelLayoutTag_MPEG_5_1_A, // L R C LFE Ls Rs kAudioChannelLayoutTag_AudioUnit_6_1 = kAudioChannelLayoutTag_MPEG_6_1_A, // L R C LFE Ls Rs Cs kAudioChannelLayoutTag_AudioUnit_7_1 = kAudioChannelLayoutTag_MPEG_7_1_C, // L R C LFE Ls Rs Rls Rrs kAudioChannelLayoutTag_AAC_Quadraphonic = kAudioChannelLayoutTag_Quadraphonic, // L R Ls Rs kAudioChannelLayoutTag_AAC_4_0 = kAudioChannelLayoutTag_MPEG_4_0_B, // C L R Cs kAudioChannelLayoutTag_AAC_5_0 = kAudioChannelLayoutTag_MPEG_5_0_D, // C L R Ls Rs kAudioChannelLayoutTag_AAC_5_1 = kAudioChannelLayoutTag_MPEG_5_1_D, // C L R Ls Rs Lfe kAudioChannelLayoutTag_AAC_6_0 = ( 141L<<16) | 6, // C L R Ls Rs Cs kAudioChannelLayoutTag_AAC_6_1 = ( 142L<<16) | 7, // C L R Ls Rs Cs Lfe kAudioChannelLayoutTag_AAC_7_0 = ( 143L<<16) | 7, // C L R Ls Rs Rls Rrs kAudioChannelLayoutTag_AAC_7_1 = kAudioChannelLayoutTag_MPEG_7_1_B, // C Lc Rc L R Ls Rs Lfe kAudioChannelLayoutTag_AAC_Octagonal = ( 144L<<16) | 8, // C L R Ls Rs Rls Rrs Cs kAudioChannelLayoutTag_TMH_10_2_std = ( 145L<<16) | 16, // L R C Vhc Lsd Rsd Ls Rs Vhl Vhr Lw Rw Csd Cs LFE1 LFE2 kAudioChannelLayoutTag_TMH_10_2_full = ( 146L<<16) | 21, // TMH_10_2_std plus: Lc Rc HI VI Haptic kAudioChannelLayoutTag_DiscreteInOrder = ( 147L<<16) | 0 // needs to be ORed with the actual number of channels };
Constants
AudioStreamBasicDescription |
Constants for use with AudioStreamBasicDescription
enum { kAudioStreamAnyRate = 0 };
kAudioStreamAnyRate- The format can use any sample rate. Note that this constant can only appear in listings of supported formats. It will never appear in a current format.
Constants
AudioTimeStamp |
The flags that indicate which fields in an AudioTimeStamp structure are valid.
enum { kAudioTimeStampSampleTimeValid = ( 1L << 0), kAudioTimeStampHostTimeValid = ( 1L << 1), kAudioTimeStampRateScalarValid = ( 1L << 2), kAudioTimeStampWordClockTimeValid = ( 1L << 3), kAudioTimeStampSMPTETimeValid = ( 1L << 4) };
kAudioTimeStampSampleTimeValid- The sample frame time is valid.
kAudioTimeStampHostTimeValid- The host time is valid.
kAudioTimeStampRateScalarValid- The rate scalar is valid.
kAudioTimeStampWordClockTimeValid- The word clock time is valid.
kAudioTimeStampSMPTETimeValid- The SMPTE time is valid.
Flags
Channel |
These constants are for use in the mChannelBitmap field of an AudioChannelLayout structure.
enum { kAudioChannelBit_Left = ( 1L<<0), kAudioChannelBit_Right = ( 1L<<1), kAudioChannelBit_Center = ( 1L<<2), kAudioChannelBit_LFEScreen = ( 1L<<3), kAudioChannelBit_LeftSurround = ( 1L<<4), // WAVE: "Back Left" kAudioChannelBit_RightSurround = ( 1L<<5), // WAVE: "Back Right" kAudioChannelBit_LeftCenter = ( 1L<<6), kAudioChannelBit_RightCenter = ( 1L<<7), kAudioChannelBit_CenterSurround = ( 1L<<8), // WAVE: "Back Center" kAudioChannelBit_LeftSurroundDirect = ( 1L<<9), // WAVE: "Side Left" kAudioChannelBit_RightSurroundDirect = ( 1L<<10), // WAVE: "Side Right" kAudioChannelBit_TopCenterSurround = ( 1L<<11), kAudioChannelBit_VerticalHeightLeft = ( 1L<<12), // WAVE: "Top Front Left" kAudioChannelBit_VerticalHeightCenter = ( 1L<<13), // WAVE: "Top Front Center" kAudioChannelBit_VerticalHeightRight = ( 1L<<14), // WAVE: "Top Front Right" kAudioChannelBit_TopBackLeft = ( 1L<<15), kAudioChannelBit_TopBackCenter = ( 1L<<16), kAudioChannelBit_TopBackRight = ( 1L<<17) };
Bitmap Constants
Channel |
These constants are used in the mChannelFlags field of an AudioChannelDescription structure.
enum { kAudioChannelFlags_AllOff = 0, kAudioChannelFlags_RectangularCoordinates = ( 1L<<0), kAudioChannelFlags_SphericalCoordinates = ( 1L<<1), kAudioChannelFlags_Meters = ( 1L<<2) };
kAudioChannelFlags_RectangularCoordinates- The channel is specified by the cartesioan coordinates of the speaker position. This flag is mutally exclusive with kAudioChannelFlags_SphericalCoordinates.
kAudioChannelFlags_SphericalCoordinates- The channel is specified by the spherical coordinates of the speaker position. This flag is mutally exclusive with kAudioChannelFlags_RectangularCoordinates.
kAudioChannelFlags_Meters- Set to indicate the units are in meters, clear to indicate the units are relative to the unit cube or unit sphere.
Coordinate Flags
Channel |
Constants for indexing 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 };
kAudioChannelCoordinates_LeftRight- For rectangulare coordinates, negative is left and positive is right.
kAudioChannelCoordinates_BackFront- For rectangulare coordinates, negative is back and positive is front.
kAudioChannelCoordinates_DownUp- For rectangulare coordinates, negative is below ground level, 0 is ground level, and positive is above ground level.
kAudioChannelCoordinates_Azimuth- For spherical coordinates, 0 is front center, positive is right, negative is left. This is measured in degrees.
kAudioChannelCoordinates_Elevation- For spherical coordinates, +90 is zenith, 0 is horizontal, -90 is nadir. This is measured in degrees.
kAudioChannelCoordinates_Distance- For spherical coordinates, the units are described by flags.
Coordinate Index Constants
Commonly |
Some commonly used combinations of flags for AudioStreamBasicDescriptions.
enum { #if TARGET_RT_BIG_ENDIAN kAudioFormatFlagsNativeEndian = kAudioFormatFlagIsBigEndian, #else kAudioFormatFlagsNativeEndian = 0, #endif kAudioFormatFlagsNativeFloatPacked = kAudioFormatFlagIsFloat | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked };
kAudioFormatFlagsNativeEndian- Defined to set or clear kAudioFormatFlagIsBigEndian depending on the endianness of the processor at build time.
kAudioFormatFlagsNativeFloatPacked- The flags for the canonical format of fully packed, native endian floating point data.
Used Combinations of ASBD Flags
Commonly |
Some commonly used combinations of AudioTimeStamp flags.
enum { kAudioTimeStampSampleHostTimeValid = ( kAudioTimeStampSampleTimeValid | kAudioTimeStampHostTimeValid) };
kAudioTimeStampSampleHostTimeValid- The sample frame time and the host time are valid.
Used Combinations of AudioTimeStamp Flags
Format |
The four char code IDs used to identify individual formats of audio data.
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', kAudioFormatDVAudio = 'dvca', kAudioFormatVariableDurationDVAudio = 'vdva', kAudioFormatTimeCode = 'time', kAudioFormatMIDIStream = 'midi', kAudioFormatParameterValueStream = 'apvs', kAudioFormatAppleLossless = 'alac' };
kAudioFormatLinearPCM- Linear PCM, uses the standard flags.
kAudioFormatAC3- AC-3, has no flags.
kAudioFormat60958AC3- AC-3 packaged for transport over an IEC 60958 compliant digital audio interface. Uses the standard flags.
kAudioFormatAppleIMA4- Apples implementation of IMA 4:1 ADPCM, has no flags.
kAudioFormatMPEG4AAC- MPEG-4 AAC, the flags field contains the MPEG-4 audio object type constant indicating the specific kind of data.
kAudioFormatMPEG4CELP- MPEG-4 CELP, the flags field contains the MPEG-4 audio object type constant indicating the specific kind of data.
kAudioFormatMPEG4HVXC- MPEG-4 HVXC, the flags field contains the MPEG-4 audio object type constant indicating the specific kind of data.
kAudioFormatMPEG4TwinVQ- MPEG-4 TwinVQ, the flags field contains the MPEG-4 audio object type constant indicating the specific kind of data.
kAudioFormatMACE3- MACE 3:1, has no flags.
kAudioFormatMACE6- MACE 6:1, has no flags.
kAudioFormatULaw- \xB5Law 2:1, has no flags.
kAudioFormatALaw- aLaw 2:1, has no flags.
kAudioFormatQDesign- QDesign music, has no flags
kAudioFormatQDesign2- QDesign2 music, has no flags
kAudioFormatQUALCOMM- QUALCOMM PureVoice, has no flags
kAudioFormatMPEGLayer1- MPEG-1/2, Layer 1 audio, has no flags
kAudioFormatMPEGLayer2- MPEG-1/2, Layer 2 audio, has no flags
kAudioFormatMPEGLayer3- MPEG-1/2, Layer 3 audio, has no flags
kAudioFormatDVAudio- DV Audio, has no flags
kAudioFormatVariableDurationDVAudio- Variable duration DV Audio, has no flags.
kAudioFormatTimeCode- A stream of IOAudioTimeStamps, uses the IOAudioTimeStamp flags (see IOKit/audio/IOAudioTypes.h).
kAudioFormatMIDIStream- A stream of MIDIPacketLists where the time stamps in the MIDIPacketList are sample offsets in the stream. The mSampleRate field is used to describe how time is passed in this kind of stream and an AudioUnit that receives or generates this stream can use this sample rate, 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. It has no flags.
kAudioFormatParameterValueStream- A "side-chain" of Float32 data that can be fed or generated by an AudioUnit and is used to send a high density of parameter value control information. An AU will typically run a ParameterValueStream at either the sample rate of the AudioUnit's audio data, or some integer divisor of this (say a half or a third of the sample rate of the audio). The Sample Rate of the ASBD describes this relationship. It has no flags.
kAudioFormatAppleLossless- Apple Lossless, has no flags.
IDs
MPEG-4 Audio Object IDs |
Constants that describe the various kinds of MPEG-4 audio data.
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 };
These constants are used in the flags field of an AudioStreamBasicDescription that describes an MPEG-4 audio stream.
SMPTE |
Constants that describe the type of SMPTE time.
enum { kSMPTETimeType24 = 0, kSMPTETimeType25 = 1, kSMPTETimeType30Drop = 2, kSMPTETimeType30 = 3, kSMPTETimeType2997 = 4, kSMPTETimeType2997Drop = 5, kSMPTETimeType60 = 6, kSMPTETimeType5994 = 7 };
kSMPTETimeType24- 24 Frame
kSMPTETimeType25- 25 Frame
kSMPTETimeType30Drop- 30 Drop Frame
kSMPTETimeType30- 30 Frame
kSMPTETimeType2997- 29.97 Frame
kSMPTETimeType2997Drop- 29.97 Drop Frame
kSMPTETimeType60- 60 Frame
kSMPTETimeType5994- 59.94 Frame
Time Types
SMPTE |
Flags that describe the SMPTE time state.
enum { kSMPTETimeValid = ( 1L << 0), kSMPTETimeRunning = ( 1L << 1) };
kSMPTETimeValid- The full time is valid.
kSMPTETimeRunning- Time is running.
State Flags
Standard Flag Values for AudioStreamBasicDescription |
These are the standard flags for use in the mFormatFlags field of the AudioStreamBasicDescription structure.
enum { kAudioFormatFlagIsFloat = ( 1L << 0), kAudioFormatFlagIsBigEndian = ( 1L << 1), kAudioFormatFlagIsSignedInteger = ( 1L << 2), kAudioFormatFlagIsPacked = ( 1L << 3), kAudioFormatFlagIsAlignedHigh = ( 1L << 4), kAudioFormatFlagIsNonInterleaved = ( 1L << 5), kAudioFormatFlagIsNonMixable = ( 1L << 6), kAudioFormatFlagsAreAllClear = ( 1L << 31), kLinearPCMFormatFlagIsFloat = kAudioFormatFlagIsFloat, kLinearPCMFormatFlagIsBigEndian = kAudioFormatFlagIsBigEndian, kLinearPCMFormatFlagIsSignedInteger = kAudioFormatFlagIsSignedInteger, kLinearPCMFormatFlagIsPacked = kAudioFormatFlagIsPacked, kLinearPCMFormatFlagIsAlignedHigh = kAudioFormatFlagIsAlignedHigh, kLinearPCMFormatFlagIsNonInterleaved = kAudioFormatFlagIsNonInterleaved, kLinearPCMFormatFlagIsNonMixable = kAudioFormatFlagIsNonMixable, kLinearPCMFormatFlagsAreAllClear = kAudioFormatFlagsAreAllClear, kAppleLosslessFormatFlag_16BitSourceData = 1, kAppleLosslessFormatFlag_20BitSourceData = 2, kAppleLosslessFormatFlag_24BitSourceData = 3, kAppleLosslessFormatFlag_32BitSourceData = 4 };
kAudioFormatFlagIsFloat- Set for floating point, clear for integer.
kAudioFormatFlagIsBigEndian- Set for big endian, clear for little endian.
kAudioFormatFlagIsSignedInteger- Set for signed integer, clear for unsigned integer. This is only valid if kAudioFormatFlagIsFloat is clear.
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.
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.
kAudioFormatFlagIsNonInterleaved- Set if the samples for each channel are located contiguously and the channels are layed out end to end, clear if the samples for each frame are layed out contiguously and the frames layed out end to end.
kAudioFormatFlagIsNonMixable- Set to indicate when a format is non-mixable. 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 uses.
kAudioFormatFlagsAreAllClear- Set if all the flags would be clear in order to preserve 0 as the wild card value.
kLinearPCMFormatFlagIsFloat- Synonym for kAudioFormatFlagIsFloat.
kLinearPCMFormatFlagIsBigEndian- Synonym for kAudioFormatFlagIsBigEndian.
kLinearPCMFormatFlagIsSignedInteger- Synonym for kAudioFormatFlagIsSignedInteger.
kLinearPCMFormatFlagIsPacked- Synonym for kAudioFormatFlagIsPacked.
kLinearPCMFormatFlagIsAlignedHigh- Synonym for kAudioFormatFlagIsAlignedHigh.
kLinearPCMFormatFlagIsNonInterleaved- Synonym for kAudioFormatFlagIsNonInterleaved.
kLinearPCMFormatFlagIsNonMixable- Synonym for kAudioFormatFlagIsNonMixable.
kLinearPCMFormatFlagsAreAllClear- Synonym for kAudioFormatFlagsAreAllClear.
kAppleLosslessFormatFlag_16BitSourceData- This flag is set for Apple Lossless data that was sourced from 16 bit native endian signed integer data.
kAppleLosslessFormatFlag_20BitSourceData- This flag is set for Apple Lossless data that was sourced from 20 bit native endian signed integer data aligned high in 24 bits.
kAppleLosslessFormatFlag_24BitSourceData- This flag is set for Apple Lossless data that was sourced from 24 bit native endian signed integer data.
kAppleLosslessFormatFlag_32BitSourceData- This flag is set for Apple Lossless data that was sourced from 32 bit native endian signed integer data.
Typically, when an ASBD is being used, the fields describe the complete layout
of the sample data in the buffers that are represented by this description -
where typically those buffers are represented by an AudioBuffer that is
contained in an AudioBufferList.
However, when an ASBD has the kAudioFormatFlagIsNonInterleaved flag, the
AudioBufferList has a different structure and semantic. In this case, the ASBD
fields will describe the format of ONE of the AudioBuffers that are contained in
the list, AND each AudioBuffer in the list is determined to have a single (mono)
channel of audio data. Then, the ASBD's mChannelsPerFrame will indicate the
total number of AudioBuffers that are contained within the AudioBufferList -
where each buffer contains one channel. This is used primarily with the
AudioUnit (and AudioConverter) representation of this list - and won't be found
in the AudioHardware usage of this structure.
AudioChannelLayoutTag_GetNumberOfChannels |
A macro to get the number of channels out of an AudioChannelLayoutTag
#define AudioChannelLayoutTag_GetNumberOfChannels(layoutTag)
layoutTagThe number of channels the tag indicates.
The low 16 bits of an AudioChannelLayoutTag gives the number of channels except for kAudioChannelLayoutTag_UseChannelDescriptions and kAudioChannelLayoutTag_UseChannelBitmap.
TestAudioFormatNativeEndian |
A macro for checking if an ASBD indicates native endian linear PCM data.
#define TestAudioFormatNativeEndian(f)
|