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Retired Document

Important: This sample code may not represent best practices for current development. The project may use deprecated symbols and illustrate technologies and techniques that are no longer recommended.

Relevant replacement documents include:

http://developer.apple.com/library/mac/samplecode/sc2195/Introduction/Intro.html#//apple_ref/doc/uid/DTS40013969

PublicUtility/CAStreamBasicDescription.h

/*

 <codex>

 <abstract>Part of CoreAudio Utility Classes</abstract>

 <\codex>

*/

#ifndef __CAStreamBasicDescription_h__

#define __CAStreamBasicDescription_h__

#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)

    #include <CoreAudio/CoreAudioTypes.h>

    #include <CoreFoundation/CoreFoundation.h>

#else

    #include "CoreAudioTypes.h"

    #include "CoreFoundation.h"

#endif

#include "CADebugMacros.h"

#include <string.h> // for memset, memcpy

#include <stdio.h>  // for FILE *

#pragma mark    This file needs to compile on more earlier versions of the OS, so please keep that in mind when editing it

extern char *CAStringForOSType (OSType t, char *writeLocation);

// define Leopard specific symbols for backward compatibility if applicable

#if COREAUDIOTYPES_VERSION < 1050

typedef Float32 AudioSampleType;

enum { kAudioFormatFlagsCanonical = kAudioFormatFlagIsFloat | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked };

#endif

#if COREAUDIOTYPES_VERSION < 1051

typedef Float32 AudioUnitSampleType;

enum {

    kLinearPCMFormatFlagsSampleFractionShift    = 7,

    kLinearPCMFormatFlagsSampleFractionMask     = (0x3F << kLinearPCMFormatFlagsSampleFractionShift),

};

#endif

//  define the IsMixable format flag for all versions of the system

#if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_3)

    enum { kIsNonMixableFlag = kAudioFormatFlagIsNonMixable };

#else

    enum { kIsNonMixableFlag = (1L << 6) };

#endif

//=============================================================================

//  CAStreamBasicDescription

//

//  This is a wrapper class for the AudioStreamBasicDescription struct.

//  It adds a number of convenience routines, but otherwise adds nothing

//  to the footprint of the original struct.

//=============================================================================

class CAStreamBasicDescription :

    public AudioStreamBasicDescription

//  Constants

public:

    static const AudioStreamBasicDescription    sEmpty;

    enum CommonPCMFormat {

        kPCMFormatOther     = 0,

        kPCMFormatFloat32   = 1,

        kPCMFormatInt16     = 2,

        kPCMFormatFixed824  = 3

};

//  Construction/Destruction

public:

    CAStreamBasicDescription();

    CAStreamBasicDescription(const AudioStreamBasicDescription &desc);

    CAStreamBasicDescription(       double inSampleRate,        UInt32 inFormatID,

                                    UInt32 inBytesPerPacket,    UInt32 inFramesPerPacket,

                                    UInt32 inBytesPerFrame,     UInt32 inChannelsPerFrame,

                                    UInt32 inBitsPerChannel,    UInt32 inFormatFlags);

    CAStreamBasicDescription(   double inSampleRate, UInt32 inNumChannels, CommonPCMFormat pcmf, bool inIsInterleaved) {

        unsigned wordsize;

        mSampleRate = inSampleRate;

        mFormatID = kAudioFormatLinearPCM;

        mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked;

        mFramesPerPacket = 1;

        mChannelsPerFrame = inNumChannels;

        mBytesPerFrame = mBytesPerPacket = 0;

        mReserved = 0;

        switch (pcmf) {

        default:

            return;

        case kPCMFormatFloat32:

            wordsize = 4;

            mFormatFlags |= kAudioFormatFlagIsFloat;

            break;

        case kPCMFormatInt16:

            wordsize = 2;

            mFormatFlags |= kAudioFormatFlagIsSignedInteger;

            break;

        case kPCMFormatFixed824:

            wordsize = 4;

            mFormatFlags |= kAudioFormatFlagIsSignedInteger | (24 << kLinearPCMFormatFlagsSampleFractionShift);

            break;

        mBitsPerChannel = wordsize * 8;

        if (inIsInterleaved)

            mBytesPerFrame = mBytesPerPacket = wordsize * inNumChannels;

        else {

            mFormatFlags |= kAudioFormatFlagIsNonInterleaved;

            mBytesPerFrame = mBytesPerPacket = wordsize;

//  Assignment

    CAStreamBasicDescription&   operator=(const AudioStreamBasicDescription& v) { SetFrom(v); return *this; }

    void    SetFrom(const AudioStreamBasicDescription &desc)

        memcpy(this, &desc, sizeof(AudioStreamBasicDescription));

    bool        FromText(const char *inTextDesc) { return FromText(inTextDesc, *this); }

    static bool FromText(const char *inTextDesc, AudioStreamBasicDescription &outDesc);

                    // return true if parsing was successful

    static const char *sTextParsingUsageString;

    // _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

//

    // interrogation

    bool    IsPCM() const { return mFormatID == kAudioFormatLinearPCM; }

    bool    PackednessIsSignificant() const

        Assert(IsPCM(), "PackednessIsSignificant only applies for PCM");

        return (SampleWordSize() << 3) != mBitsPerChannel;

    bool    AlignmentIsSignificant() const

        return PackednessIsSignificant() || (mBitsPerChannel & 7) != 0;

    bool    IsInterleaved() const

        return !IsPCM() || !(mFormatFlags & kAudioFormatFlagIsNonInterleaved);

    bool    IsSignedInteger() const

        return IsPCM() && (mFormatFlags & kAudioFormatFlagIsSignedInteger);

    bool    IsFloat() const

        return IsPCM() && (mFormatFlags & kAudioFormatFlagIsFloat);

    bool    IsNativeEndian() const

        return (mFormatFlags & kAudioFormatFlagIsBigEndian) == kAudioFormatFlagsNativeEndian;

    // for sanity with interleaved/deinterleaved possibilities, never access mChannelsPerFrame, use these:

    UInt32  NumberInterleavedChannels() const   { return IsInterleaved() ? mChannelsPerFrame : 1; }

    UInt32  NumberChannelStreams() const        { return IsInterleaved() ? 1 : mChannelsPerFrame; }

    UInt32  NumberChannels() const              { return mChannelsPerFrame; }

    UInt32  SampleWordSize() const              {

            return (mBytesPerFrame > 0 && NumberInterleavedChannels()) ? mBytesPerFrame / NumberInterleavedChannels() :  0;

    UInt32  FramesToBytes(UInt32 nframes) const { return nframes * mBytesPerFrame; }

    UInt32  BytesToFrames(UInt32 nbytes) const  {

        Assert(mBytesPerFrame > 0, "bytesPerFrame must be > 0 in BytesToFrames");

        return nbytes / mBytesPerFrame;

    bool    SameChannelsAndInterleaving(const CAStreamBasicDescription &a) const

        return this->NumberChannels() == a.NumberChannels() && this->IsInterleaved() == a.IsInterleaved();

    bool    IdentifyCommonPCMFormat(CommonPCMFormat &outFormat, bool *outIsInterleaved=NULL) const

    {   // return true if it's a valid PCM format.

        outFormat = kPCMFormatOther;

        // trap out patently invalid formats.

        if (mFormatID != kAudioFormatLinearPCM || mFramesPerPacket != 1 || mBytesPerFrame != mBytesPerPacket || mBitsPerChannel/8 > mBytesPerFrame || mChannelsPerFrame == 0)

            return false;

        bool interleaved = (mFormatFlags & kAudioFormatFlagIsNonInterleaved) == 0;

        if (outIsInterleaved != NULL) *outIsInterleaved = interleaved;

        unsigned wordsize = mBytesPerFrame;

        if (interleaved) {

            if (wordsize % mChannelsPerFrame != 0) return false;

            wordsize /= mChannelsPerFrame;

        if ((mFormatFlags & kAudioFormatFlagIsBigEndian) == kAudioFormatFlagsNativeEndian

        && wordsize * 8 == mBitsPerChannel) {

            // packed and native endian, good

            if (mFormatFlags & kLinearPCMFormatFlagIsFloat) {

                // float: reject nonsense bits

                if (mFormatFlags & (kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagsSampleFractionMask))

                    return false;

                if (wordsize == 4)

                    outFormat = kPCMFormatFloat32;

            } else if (mFormatFlags & kLinearPCMFormatFlagIsSignedInteger) {

                // signed int

                unsigned fracbits = (mFormatFlags & kLinearPCMFormatFlagsSampleFractionMask) >> kLinearPCMFormatFlagsSampleFractionShift;

                if (wordsize == 4 && fracbits == 24)

                    outFormat = kPCMFormatFixed824;

                else if (wordsize == 2 && fracbits == 0)

                    outFormat = kPCMFormatInt16;

        return true;

    bool IsCommonFloat32(bool *outIsInterleaved=NULL) const {

        CommonPCMFormat fmt;

        return IdentifyCommonPCMFormat(fmt, outIsInterleaved) && fmt == kPCMFormatFloat32;

    bool IsCommonFixed824(bool *outIsInterleaved=NULL) const {

        CommonPCMFormat fmt;

        return IdentifyCommonPCMFormat(fmt, outIsInterleaved) && fmt == kPCMFormatFixed824;

    bool IsCommonInt16(bool *outIsInterleaved=NULL) const {

        CommonPCMFormat fmt;

        return IdentifyCommonPCMFormat(fmt, outIsInterleaved) && fmt == kPCMFormatInt16;

    // _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

//

    //  manipulation

    void    SetCanonical(UInt32 nChannels, bool interleaved)

                // note: leaves sample rate untouched

        mFormatID = kAudioFormatLinearPCM;

        int sampleSize = SizeOf32(AudioSampleType);

        mFormatFlags = kAudioFormatFlagsCanonical;

        mBitsPerChannel = 8 * sampleSize;

        mChannelsPerFrame = nChannels;

        mFramesPerPacket = 1;

        if (interleaved)

            mBytesPerPacket = mBytesPerFrame = nChannels * sampleSize;

        else {

            mBytesPerPacket = mBytesPerFrame = sampleSize;

            mFormatFlags |= kAudioFormatFlagIsNonInterleaved;

    bool    IsCanonical() const

        if (mFormatID != kAudioFormatLinearPCM) return false;

        UInt32 reqFormatFlags;

        UInt32 flagsMask = (kLinearPCMFormatFlagIsFloat | kLinearPCMFormatFlagIsBigEndian | kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked | kLinearPCMFormatFlagsSampleFractionMask);

        bool interleaved = (mFormatFlags & kAudioFormatFlagIsNonInterleaved) == 0;

        unsigned sampleSize = SizeOf32(AudioSampleType);

        reqFormatFlags = kAudioFormatFlagsCanonical;

        UInt32 reqFrameSize = interleaved ? (mChannelsPerFrame * sampleSize) : sampleSize;

        return ((mFormatFlags & flagsMask) == reqFormatFlags

            && mBitsPerChannel == 8 * sampleSize

            && mFramesPerPacket == 1

            && mBytesPerFrame == reqFrameSize

            && mBytesPerPacket == reqFrameSize);

    void    SetAUCanonical(UInt32 nChannels, bool interleaved)

        mFormatID = kAudioFormatLinearPCM;

#if CA_PREFER_FIXED_POINT

        mFormatFlags = kAudioFormatFlagsCanonical | (kAudioUnitSampleFractionBits << kLinearPCMFormatFlagsSampleFractionShift);

#else

        mFormatFlags = kAudioFormatFlagsCanonical;

#endif

        mChannelsPerFrame = nChannels;

        mFramesPerPacket = 1;

        mBitsPerChannel = 8 * SizeOf32(AudioUnitSampleType);

        if (interleaved)

            mBytesPerPacket = mBytesPerFrame = nChannels * SizeOf32(AudioUnitSampleType);

        else {

            mBytesPerPacket = mBytesPerFrame = SizeOf32(AudioUnitSampleType);

            mFormatFlags |= kAudioFormatFlagIsNonInterleaved;

    void    ChangeNumberChannels(UInt32 nChannels, bool interleaved)

                // alter an existing format

        Assert(IsPCM(), "ChangeNumberChannels only works for PCM formats");

        UInt32 wordSize = SampleWordSize(); // get this before changing ANYTHING

        if (wordSize == 0)

            wordSize = (mBitsPerChannel + 7) / 8;

        mChannelsPerFrame = nChannels;

        mFramesPerPacket = 1;

        if (interleaved) {

            mBytesPerPacket = mBytesPerFrame = nChannels * wordSize;

            mFormatFlags &= ~kAudioFormatFlagIsNonInterleaved;

        } else {

            mBytesPerPacket = mBytesPerFrame = wordSize;

            mFormatFlags |= kAudioFormatFlagIsNonInterleaved;

    // _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

//

    //  other

    bool    IsEqual(const AudioStreamBasicDescription &other, bool interpretingWildcards=true) const;

    void    Print() const {

        Print (stdout);

    void    Print(FILE* file) const {

        PrintFormat (file, "", "AudioStreamBasicDescription:");

    void    PrintFormat(FILE *f, const char *indent, const char *name) const {

        char buf[256];

        fprintf(f, "%s%s %s\n", indent, name, AsString(buf, sizeof(buf)));

    void    PrintFormat2(FILE *f, const char *indent, const char *name) const { // no trailing newline

        char buf[256];

        fprintf(f, "%s%s %s", indent, name, AsString(buf, sizeof(buf)));

    char *  AsString(char *buf, size_t bufsize) const;

    static void Print (const AudioStreamBasicDescription &inDesc)

        CAStreamBasicDescription desc(inDesc);

        desc.Print ();

    OSStatus            Save(CFPropertyListRef *outData) const;

    OSStatus            Restore(CFPropertyListRef &inData);

//  Operations

    static bool         IsMixable(const AudioStreamBasicDescription& inDescription) { return (inDescription.mFormatID == kAudioFormatLinearPCM) && ((inDescription.mFormatFlags & kIsNonMixableFlag) == 0); }

    static void         NormalizeLinearPCMFormat(AudioStreamBasicDescription& ioDescription);

    static void         NormalizeLinearPCMFormat(bool inNativeEndian, AudioStreamBasicDescription& ioDescription);

    static void         ResetFormat(AudioStreamBasicDescription& ioDescription);

    static void         FillOutFormat(AudioStreamBasicDescription& ioDescription, const AudioStreamBasicDescription& inTemplateDescription);

    static void         GetSimpleName(const AudioStreamBasicDescription& inDescription, char* outName, UInt32 inMaxNameLength, bool inAbbreviate, bool inIncludeSampleRate = false);

#if CoreAudio_Debug

    static void         PrintToLog(const AudioStreamBasicDescription& inDesc);

#endif

};

bool        operator<(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y);

bool        operator==(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y);

#if TARGET_OS_MAC || (TARGET_OS_WIN32 && (_MSC_VER > 600))

inline bool operator!=(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) { return !(x == y); }

inline bool operator<=(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) { return (x < y) || (x == y); }

inline bool operator>=(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) { return !(x < y); }

inline bool operator>(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) { return !((x < y) || (x == y)); }

#endif

bool SanityCheck(const AudioStreamBasicDescription& x);

#endif // __CAStreamBasicDescription_h__

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