Audio Queue錄製 播放原理

typedef struct AudioQueueBuffer {
const UInt32mAudioDataBytesCapacity;
void *constmAudioData;
UInt32mAudioDataByteSize;
void*mUserData;
} AudioQueueBuffer;
typedef AudioQueueBuffer *AudioQueueBufferRef;

AudioQueueInputCallback (
void*inUserData,
AudioQueueRefinAQ,
AudioQueueBufferRefinBuffer,
const AudioTimeStamp*inStartTime,
UInt32inNumberPacketDescriptions,
const AudioStreamPacketDescription *inPacketDescs
);

AudioQueueOutputCallback (
void*inUserData,
AudioQueueRefinAQ,
AudioQueueBufferRefinBuffer
);

static const int kNumberBuffers = 3;// 1
struct AQRecorderState {
AudioStreamBasicDescriptionmDataFormat;// 2
AudioQueueRefmQueue;// 3
AudioQueueBufferRefmBuffers[kNumberBuffers];// 4
AudioFileIDmAudioFile;// 5
UInt32bufferByteSize;// 6
SInt64mCurrentPacket;// 7
boolmIsRunning;// 8
};

static void HandleInputBuffer (
void*aqData,// 1
AudioQueueRefinAQ,// 2
AudioQueueBufferRefinBuffer,// 3
const AudioTimeStamp*inStartTime,// 4
UInt32inNumPackets,// 5
const AudioStreamPacketDescription*inPacketDesc// 6
)

AudioFileWritePackets (// 1
pAqData->mAudioFile,// 2
false,// 3
inBuffer->mAudioDataByteSize,// 4
inPacketDesc,// 5
pAqData->mCurrentPacket,// 6
&inNumPackets,// 7
inBuffer->mAudioData// 8
);

AudioQueueEnqueueBuffer (// 1
pAqData->mQueue,// 2
inBuffer,// 3
0,// 4
NULL// 5
);

static void HandleInputBuffer (
void*aqData,
AudioQueueRefinAQ,
AudioQueueBufferRefinBuffer,
const AudioTimeStamp*inStartTime,
UInt32inNumPackets,
const AudioStreamPacketDescription*inPacketDesc
) {
AQRecorderState *pAqData = (AQRecorderState *) aqData;// 1
 
if (inNumPackets == 0 &&// 2
pAqData->mDataFormat.mBytesPerPacket != 0)
inNumPackets =
inBuffer->mAudioDataByteSize / pAqData->mDataFormat.mBytesPerPacket;
 
if (AudioFileWritePackets (// 3
pAqData->mAudioFile,
false,
inBuffer->mAudioDataByteSize,
inPacketDesc,
pAqData->mCurrentPacket,
&inNumPackets,
inBuffer->mAudioData
) == noErr) {
pAqData->mCurrentPacket += inNumPackets;// 4
}
if (pAqData->mIsRunning == 0)// 5
return;
 
AudioQueueEnqueueBuffer (// 6
pAqData->mQueue,
inBuffer,
0,
NULL
);
}

void DeriveBufferSize (
AudioQueueRefaudioQueue,// 1
AudioStreamBasicDescription&ASBDescription,// 2
Float64seconds,// 3
UInt32*outBufferSize// 4
) {
static const int maxBufferSize = 0x50000;// 5
 
int maxPacketSize = ASBDescription.mBytesPerPacket;// 6
if (maxPacketSize == 0) {// 7
UInt32 maxVBRPacketSize = sizeof(maxPacketSize);
AudioQueueGetProperty (
audioQueue,
kAudioQueueProperty_MaximumOutputPacketSize,
// in Mac OS X v10.5, instead use
//kAudioConverterPropertyMaximumOutputPacketSize
&maxPacketSize,
&maxVBRPacketSize
);
}
 
Float64 numBytesForTime =
ASBDescription.mSampleRate * maxPacketSize * seconds; // 8
*outBufferSize =
UInt32 (numBytesForTime < maxBufferSize ?
numBytesForTime : maxBufferSize);// 9
}

OSStatus SetMagicCookieForFile (
AudioQueueRef inQueue,// 1
AudioFileIDinFile// 2
) {
OSStatus result = noErr;// 3
UInt32 cookieSize;// 4
 
if (
AudioQueueGetPropertySize (// 5
inQueue,
kAudioQueueProperty_MagicCookie,
&cookieSize
) == noErr
) {
char* magicCookie =
(char *) malloc (cookieSize);// 6
if (
AudioQueueGetProperty (// 7
inQueue,
kAudioQueueProperty_MagicCookie,
magicCookie,
&cookieSize
) == noErr
)
result =AudioFileSetProperty (// 8
inFile,
kAudioFilePropertyMagicCookieData,
cookieSize,
magicCookie
);
free (magicCookie);// 9
}
return result;// 10
}

AQRecorderState aqData;// 1
 
aqData.mDataFormat.mFormatID= kAudioFormatLinearPCM; // 2
aqData.mDataFormat.mSampleRate= 44100.0;// 3
aqData.mDataFormat.mChannelsPerFrame = 2;// 4
aqData.mDataFormat.mBitsPerChannel= 16;// 5
aqData.mDataFormat.mBytesPerPacket=// 6
aqData.mDataFormat.mBytesPerFrame =
aqData.mDataFormat.mChannelsPerFrame * sizeof (SInt16);
aqData.mDataFormat.mFramesPerPacket= 1;// 7
 
AudioFileTypeID fileType= kAudioFileAIFFType;// 8
aqData.mDataFormat.mFormatFlags =// 9
kLinearPCMFormatFlagIsBigEndian
| kLinearPCMFormatFlagIsSignedInteger
| kLinearPCMFormatFlagIsPacked;

AudioQueueNewInput (// 1
&aqData.mDataFormat,// 2
HandleInputBuffer,// 3
&aqData,// 4
NULL,// 5
kCFRunLoopCommonModes,// 6
0,// 7
&aqData.mQueue// 8
);

UInt32 dataFormatSize = sizeof (aqData.mDataFormat);// 1
 
AudioQueueGetProperty (// 2
aqData.mQueue,// 3
kAudioQueueProperty_StreamDescription,// 4
// in Mac OS X, instead use
//kAudioConverterCurrentInputStreamDescription
&aqData.mDataFormat,// 5
&dataFormatSize// 6
);

CFURLRef audioFileURL =
CFURLCreateFromFileSystemRepresentation (// 1
NULL,// 2
(const UInt8 *) filePath,// 3
strlen (filePath),// 4
false// 5
);
 
AudioFileCreateWithURL (// 6
audioFileURL,// 7
fileType,// 8
&aqData.mDataFormat,// 9
kAudioFileFlags_EraseFile,// 10
&aqData.mAudioFile// 11
);

DeriveBufferSize (// 1
aqData.mQueue,// 2
aqData.mDataFormat,// 3
0.5,// 4
&aqData.bufferByteSize// 5
);

for (int i = 0; i < kNumberBuffers; ++i) {// 1
AudioQueueAllocateBuffer (// 2
aqData.mQueue,// 3
aqData.bufferByteSize,// 4
&aqData.mBuffers[i]// 5
);
 
AudioQueueEnqueueBuffer (// 6
aqData.mQueue,// 7
aqData.mBuffers[i],// 8
0,// 9
NULL// 10
);
}

aqData.mCurrentPacket = 0;// 1
aqData.mIsRunning = true;// 2
 
AudioQueueStart (// 3
aqData.mQueue,// 4
NULL// 5
);
// Wait, on user interface thread, until user stops the recording
AudioQueueStop (// 6
aqData.mQueue,// 7
true// 8
);
 
aqData.mIsRunning = false;// 9

AudioQueueDispose (// 1
aqData.mQueue,// 2
true// 3
);
 
AudioFileClose (aqData.mAudioFile);// 4

static const int kNumberBuffers = 3;// 1
struct AQPlayerState {
AudioStreamBasicDescriptionmDataFormat;// 2
AudioQueueRefmQueue;// 3
AudioQueueBufferRefmBuffers[kNumberBuffers];// 4
AudioFileIDmAudioFile;// 5
UInt32bufferByteSize;// 6
SInt64mCurrentPacket;// 7
UInt32mNumPacketsToRead;// 8
AudioStreamPacketDescription*mPacketDescs;// 9
boolmIsRunning;// 10
};

static void HandleOutputBuffer (
void*aqData,// 1
AudioQueueRefinAQ,// 2
AudioQueueBufferRefinBuffer// 3
)

AudioFileReadPackets (// 1
pAqData->mAudioFile,// 2
false,// 3
&numBytesReadFromFile,// 4
pAqData->mPacketDescs,// 5
pAqData->mCurrentPacket,// 6
&numPackets,// 7
inBuffer->mAudioData// 8
);

AudioQueueEnqueueBuffer (// 1
pAqData->mQueue,// 2
inBuffer,// 3
(pAqData->mPacketDescs ? numPackets : 0),// 4
pAqData->mPacketDescs// 5
);

if (numPackets == 0) {// 1
AudioQueueStop (// 2
pAqData->mQueue,// 3
false// 4
);
pAqData->mIsRunning = false;// 5
}

static void HandleOutputBuffer (
void*aqData,
AudioQueueRefinAQ,
AudioQueueBufferRef inBuffer
) {
AQPlayerState *pAqData = (AQPlayerState *) aqData;// 1
if (pAqData->mIsRunning == 0) return;// 2
UInt32 numBytesReadFromFile;// 3
UInt32 numPackets = pAqData->mNumPacketsToRead;// 4
AudioFileReadPackets (
pAqData->mAudioFile,
false,
&numBytesReadFromFile,
pAqData->mPacketDescs, 
pAqData->mCurrentPacket,
&numPackets,
inBuffer->mAudioData 
);
if (numPackets > 0) {// 5
inBuffer->mAudioDataByteSize = numBytesReadFromFile;// 6
AudioQueueEnqueueBuffer ( 
pAqData->mQueue,
inBuffer,
(pAqData->mPacketDescs ? numPackets : 0),
pAqData->mPacketDescs
);
pAqData->mCurrentPacket += numPackets;// 7 
} else {
AudioQueueStop (
pAqData->mQueue,
false
);
pAqData->mIsRunning = false; 
}
}

void DeriveBufferSize (
AudioStreamBasicDescription &ASBDesc,// 1
UInt32maxPacketSize,// 2
Float64seconds,// 3
UInt32*outBufferSize,// 4
UInt32*outNumPacketsToRead// 5
) {
static const int maxBufferSize = 0x50000;// 6
static const int minBufferSize = 0x4000;// 7
 
if (ASBDesc.mFramesPerPacket != 0) {// 8
Float64 numPacketsForTime =
ASBDesc.mSampleRate / ASBDesc.mFramesPerPacket * seconds;
*outBufferSize = numPacketsForTime * maxPacketSize;
} else {// 9
*outBufferSize =
maxBufferSize > maxPacketSize ?
maxBufferSize : maxPacketSize;
}
 
if (// 10
*outBufferSize > maxBufferSize &&
*outBufferSize > maxPacketSize
)
*outBufferSize = maxBufferSize;
else {// 11
if (*outBufferSize < minBufferSize)
*outBufferSize = minBufferSize;
}
 
*outNumPacketsToRead = *outBufferSize / maxPacketSize;// 12
}

CFURLRef audioFileURL =
CFURLCreateFromFileSystemRepresentation (// 1
NULL,// 2
(const UInt8 *) filePath,// 3
strlen (filePath),// 4
false// 5
);

AQPlayerState aqData;// 1
 
OSStatus result =
AudioFileOpenURL (// 2
audioFileURL,// 3
fsRdPerm,// 4
0,// 5
&aqData.mAudioFile// 6
);
 
CFRelease (audioFileURL);// 7

UInt32 dataFormatSize = sizeof (aqData.mDataFormat);// 1
 
AudioFileGetProperty (// 2
aqData.mAudioFile,// 3
kAudioFilePropertyDataFormat,// 4
&dataFormatSize,// 5
&aqData.mDataFormat// 6
);

AudioQueueNewOutput (// 1
&aqData.mDataFormat,// 2
HandleOutputBuffer,// 3
&aqData,// 4
CFRunLoopGetCurrent (),// 5
kCFRunLoopCommonModes,// 6
0,// 7
&aqData.mQueue// 8
);

UInt32 maxPacketSize;
UInt32 propertySize = sizeof (maxPacketSize);
AudioFileGetProperty (// 1
aqData.mAudioFile,// 2
kAudioFilePropertyPacketSizeUpperBound,// 3
&propertySize,// 4
&maxPacketSize// 5
);
 
DeriveBufferSize (// 6
aqData.mDataFormat,// 7
maxPacketSize,// 8
0.5,// 9
&aqData.bufferByteSize,// 10
&aqData.mNumPacketsToRead// 11
);

bool isFormatVBR = (// 1
aqData.mDataFormat.mBytesPerPacket == 0 ||
aqData.mDataFormat.mFramesPerPacket == 0
);
 
if (isFormatVBR) {// 2
aqData.mPacketDescs =
(AudioStreamPacketDescription*) malloc (
aqData.mNumPacketsToRead * sizeof (AudioStreamPacketDescription)
);
} else {// 3
aqData.mPacketDescs = NULL;
}

UInt32 cookieSize = sizeof (UInt32);// 1
bool couldNotGetProperty =// 2
AudioFileGetPropertyInfo (// 3
aqData.mAudioFile,// 4
kAudioFilePropertyMagicCookieData,// 5
&cookieSize,// 6
NULL// 7
);
 
if (!couldNotGetProperty && cookieSize) {// 8
char* magicCookie =
(char *) malloc (cookieSize);
 
AudioFileGetProperty (// 9
aqData.mAudioFile,// 10
kAudioFilePropertyMagicCookieData,// 11
&cookieSize,// 12
magicCookie// 13
);
 
AudioQueueSetProperty (// 14
aqData.mQueue,// 15
kAudioQueueProperty_MagicCookie,// 16
magicCookie,// 17
cookieSize// 18
);
 
free (magicCookie);// 19
}

aqData.mCurrentPacket = 0;// 1
 
for (int i = 0; i < kNumberBuffers; ++i) {// 2
AudioQueueAllocateBuffer (// 3
aqData.mQueue,// 4
aqData.bufferByteSize,// 5
&aqData.mBuffers[i]// 6
);
 
HandleOutputBuffer (// 7
&aqData,// 8
aqData.mQueue,// 9
aqData.mBuffers[i]// 10
);
}

Float32 gain = 1.0;// 1
// Optionally, allow user to override gain setting here
AudioQueueSetParameter (// 2
aqData.mQueue,// 3
kAudioQueueParam_Volume,// 4
gain// 5
);

aqData.mIsRunning = true;// 1
 
AudioQueueStart (// 2
aqData.mQueue,// 3
NULL// 4
);
 
do {// 5
CFRunLoopRunInMode (// 6
kCFRunLoopDefaultMode,// 7
0.25,// 8
false// 9
);
} while (aqData.mIsRunning);
 
CFRunLoopRunInMode (// 10
kCFRunLoopDefaultMode,
1,
false
);

AudioQueueDispose (// 1
aqData.mQueue,// 2
true// 3
);
 
AudioFileClose (aqData.mAudioFile);// 4
 
free (aqData.mPacketDescs);// 5