Ограничение размера аудио буфера

В настоящее время я использую кусочек скрипта Apple «iPhoneMixerEQGraphTest» для воспроизведения звука в моем приложении, однако они не «буферизируют», а сразу отправляют все данные в буфер, что, по моему мнению, вызывает перегрузку моего приложения. Я получаю память более 100 МБ, а затем сбой. Память обычно меньше 20 МБ. Как бы я мог вызывать аудио для чтения только в буферную часть аудио, а не в целом? Сбой происходит при обратном вызове: memcpy(out, &in[sample], ioData->mBuffers[0].mDataByteSize);,

Я загружаю свое аудио этим методом:

- (void)setPlayerItem:(PlayerItem *)item{
mUserData.frameNum = 0;
mUserData.maxNumFrames = 0;

for (int i = 0; i < 1 && i < MAXBUFS; i++)  {
printf("loadFiles, %d\n", i);

ExtAudioFileRef xafref = 0;
OSStatus result = ExtAudioFileOpenURL((__bridge CFURLRef)[item url], &xafref);
if (result || 0 == xafref) { printf("ExtAudioFileOpenURL result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

// get the file data format, this represents the file's actual data format
// for informational purposes only -- the client format set on ExtAudioFile is what we really want back
CAStreamBasicDescription fileFormat;
UInt32 propSize = sizeof(fileFormat);

result = ExtAudioFileGetProperty(xafref, kExtAudioFileProperty_FileDataFormat, &propSize, &fileFormat);
if (result) { printf("ExtAudioFileGetProperty kExtAudioFileProperty_FileDataFormat result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

printf("file %d, native file format\n", i);
fileFormat.Print();

// set the client format to be what we want back
// this is the same format audio we're giving to the the mixer input
result = ExtAudioFileSetProperty(xafref, kExtAudioFileProperty_ClientDataFormat, sizeof(mClientFormat), &mClientFormat);
if (result) { printf("ExtAudioFileSetProperty kExtAudioFileProperty_ClientDataFormat %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

// get the file's length in sample frames
UInt64 numFrames = 0;
propSize = sizeof(numFrames);
result = ExtAudioFileGetProperty(xafref, kExtAudioFileProperty_FileLengthFrames, &propSize, &numFrames);
if (result || numFrames == 0) { printf("ExtAudioFileGetProperty kExtAudioFileProperty_FileLengthFrames result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

// keep track of the largest number of source frames
if (numFrames > mUserData.maxNumFrames) mUserData.maxNumFrames = numFrames;

// set up our buffer
mUserData.soundBuffer[i].numFrames = numFrames;
mUserData.soundBuffer[i].asbd = mClientFormat;

UInt32 samples = numFrames * mUserData.soundBuffer[i].asbd.mChannelsPerFrame;
mUserData.soundBuffer[i].data = (AudioSampleType *)calloc(samples, sizeof(AudioSampleType));

// set up a AudioBufferList to read data into
AudioBufferList bufList;
bufList.mNumberBuffers = 1;
bufList.mBuffers[0].mNumberChannels = mUserData.soundBuffer[i].asbd.mChannelsPerFrame;
bufList.mBuffers[0].mData = mUserData.soundBuffer[i].data;
bufList.mBuffers[0].mDataByteSize = samples * sizeof(AudioSampleType);

// perform a synchronous sequential read of the audio data out of the file into our allocated data buffer
UInt32 numPackets = numFrames;
result = ExtAudioFileRead(xafref, &numPackets, &bufList);
if (result) {
printf("ExtAudioFileRead result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result);
free(mUserData.soundBuffer[i].data);
mUserData.soundBuffer[i].data = 0;
return;
}

// close the file and dispose the ExtAudioFileRef
ExtAudioFileDispose(xafref);
}
}

Играется с:

// create a new AUGraph
result = NewAUGraph(&mGraph);
if (result) { printf("NewAUGraph result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

// create three Audio Component Descriptons for the AUs we want in the graph using the CAComponentDescription helper class

// output unit
CAComponentDescription output_desc(kAudioUnitType_Output, kAudioUnitSubType_RemoteIO, kAudioUnitManufacturer_Apple);

// iPodEQ unit
CAComponentDescription eq_desc(kAudioUnitType_Effect, kAudioUnitSubType_AUiPodEQ, kAudioUnitManufacturer_Apple);

// multichannel mixer unit
CAComponentDescription mixer_desc(kAudioUnitType_Mixer, kAudioUnitSubType_MultiChannelMixer, kAudioUnitManufacturer_Apple);

printf("add nodes\n");

// create a node in the graph that is an AudioUnit, using the supplied AudioComponentDescription to find and open that unit
result = AUGraphAddNode(mGraph, &output_desc, &outputNode);
if (result) { printf("AUGraphNewNode 1 result %lu %4.4s\n", result, (char*)&result); return; }

result = AUGraphAddNode(mGraph, &eq_desc, &eqNode);
if (result) { printf("AUGraphNewNode 2 result %lu %4.4s\n", result, (char*)&result); return; }

result = AUGraphAddNode(mGraph, &mixer_desc, &mixerNode);
if (result) { printf("AUGraphNewNode 3 result %lu %4.4s\n", result, (char*)&result); return; }

// connect a node's output to a node's input
// mixer -> eq -> output
result = AUGraphConnectNodeInput(mGraph, mixerNode, 0, eqNode, 0);
if (result) { printf("AUGraphConnectNodeInput result %lu %4.4s\n", result, (char*)&result); return; }

result = AUGraphConnectNodeInput(mGraph, eqNode, 0, outputNode, 0);
if (result) { printf("AUGraphConnectNodeInput result %lu %4.4s\n", result, (char*)&result); return; }

// open the graph AudioUnits are open but not initialized (no resource allocation occurs here)
result = AUGraphOpen(mGraph);
if (result) { printf("AUGraphOpen result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

// grab the audio unit instances from the nodes
result = AUGraphNodeInfo(mGraph, mixerNode, NULL, &mMixer);
if (result) { printf("AUGraphNodeInfo result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

result = AUGraphNodeInfo(mGraph, eqNode, NULL, &mEQ);
if (result) { printf("AUGraphNodeInfo result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

// set bus count
UInt32 numbuses = 2;

printf("set input bus count %lu\n", numbuses);

result = AudioUnitSetProperty(mMixer, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &numbuses, sizeof(numbuses));
if (result) { printf("AudioUnitSetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

for (UInt32 i = 0; i < numbuses; ++i) {
// setup render callback struct
AURenderCallbackStruct rcbs;
rcbs.inputProc = &renderInput;
rcbs.inputProcRefCon = &mUserData;

printf("set AUGraphSetNodeInputCallback\n");

// set a callback for the specified node's specified input
result = AUGraphSetNodeInputCallback(mGraph, mixerNode, i, &rcbs);
if (result) { printf("AUGraphSetNodeInputCallback result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

printf("set input bus %d, client kAudioUnitProperty_StreamFormat\n", (unsigned int)i);

// set the input stream format, this is the format of the audio for mixer input
result = AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, i, &mClientFormat, sizeof(mClientFormat));
if (result) { printf("AudioUnitSetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }
}

printf("get EQ kAudioUnitProperty_FactoryPresets\n");

// get the eq's factory preset list -- this is a read-only CFArray array of AUPreset structures
// host owns the retuned array and should release it when no longer needed
UInt32 size = sizeof(mEQPresetsArray);
result = AudioUnitGetProperty(mEQ, kAudioUnitProperty_FactoryPresets, kAudioUnitScope_Global, 0, &mEQPresetsArray, &size);
if (result) { printf("AudioUnitGetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

/* this code can be used if you're interested in dumping out the preset list
printf("iPodEQ Factory Preset List:\n");
UInt8 count = CFArrayGetCount(mEQPresetsArray);
for (int i = 0; i < count; ++i) {
AUPreset *aPreset = (AUPreset*)CFArrayGetValueAtIndex(mEQPresetsArray, i);
CFShow(aPreset->presetName);
}*/

printf("set output kAudioUnitProperty_StreamFormat\n");

// set the output stream format of the mixer
result = AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, &mOutputFormat, sizeof(mOutputFormat));
if (result) { printf("AudioUnitSetProperty result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

printf("set render notification\n");

// add a render notification, this is a callback that the graph will call every time the graph renders
// the callback will be called once before the graph’s render operation, and once after the render operation is complete
result = AUGraphAddRenderNotify(mGraph, renderNotification, &mUserData);
if (result) { printf("AUGraphAddRenderNotify result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

printf("AUGraphInitialize\n");

// now that we've set everything up we can initialize the graph, this will also validate the connections
result = AUGraphInitialize(mGraph);
if (result) { printf("AUGraphInitialize result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }

CAShow(mGraph);
OSStatus result = AUGraphStart(mGraph);
if (result) { printf("AUGraphStart result %ld %08X %4.4s\n", result, (unsigned int)result, (char*)&result); return; }
mIsPlaying = true;

Наконец я получаю ответный звонок от:

static OSStatus renderInput(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData)
{
SourceAudioBufferDataPtr userData = (SourceAudioBufferDataPtr)inRefCon;

AudioSampleType *in = userData->soundBuffer[inBusNumber].data;
AudioSampleType *out = (AudioSampleType *)ioData->mBuffers[0].mData;

UInt32 sample = userData->frameNum * userData->soundBuffer[inBusNumber].asbd.mChannelsPerFrame;

// make sure we don't attempt to render more data than we have available in the source buffers
// if one buffer is larger than the other, just render silence for that bus until we loop around again
if ((userData->frameNum + inNumberFrames) > userData->soundBuffer[inBusNumber].numFrames) {
UInt32 offset = (userData->frameNum + inNumberFrames) - userData->soundBuffer[inBusNumber].numFrames;
if (offset < inNumberFrames) {
// copy the last bit of source
SilenceData(ioData);
memcpy(out, &in[sample], ((inNumberFrames - offset) * userData->soundBuffer[inBusNumber].asbd.mBytesPerFrame));
return noErr;
} else {
// we have no source data
SilenceData(ioData);
*ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
return noErr;
}
}

memcpy(out, &in[sample], ioData->mBuffers[0].mDataByteSize);

//printf("render input bus %ld from sample %ld\n", inBusNumber, sample);

return noErr;
}