ExtAudioFileWrite para m4a / aac falhando em dispositivos dual-core (ipad 2, iphone 4s)
Eu escrevi um loop para codificar dados de áudio pcm gerados pelo meu aplicativo no aac usando o Extended Audio File Services. A codificação ocorre em um thread de segundo plano de forma síncrona e não em tempo rea
A codificação funciona perfeitamente no ipad 1 e no iphone 3gs / 4 para os ios 4 e 5. No entanto, para dispositivos de núcleo duplo (iphone 4s, ipad 2), a terceira chamada para ExtAudioFileWrite trava o encadeamento de codificação sem rastreamento de pilha e sem erros código
Aqui está o código em questão:
Os formatos de dados
AudioStreamBasicDescription AUCanonicalASBD(Float64 sampleRate,
UInt32 channel){
AudioStreamBasicDescription audioFormat;
audioFormat.mSampleRate = sampleRate;
audioFormat.mFormatID = kAudioFormatLinearPCM;
audioFormat.mFormatFlags = kAudioFormatFlagsAudioUnitCanonical;
audioFormat.mChannelsPerFrame = channel;
audioFormat.mBytesPerPacket = sizeof(AudioUnitSampleType);
audioFormat.mBytesPerFrame = sizeof(AudioUnitSampleType);
audioFormat.mFramesPerPacket = 1;
audioFormat.mBitsPerChannel = 8 * sizeof(AudioUnitSampleType);
audioFormat.mReserved = 0;
return audioFormat;
}
AudioStreamBasicDescription MixdownAAC(void){
AudioStreamBasicDescription audioFormat;
audioFormat.mSampleRate = 44100.0;
audioFormat.mFormatID = kAudioFormatMPEG4AAC;
audioFormat.mFormatFlags = kMPEG4Object_AAC_Main;
audioFormat.mChannelsPerFrame = 2;
audioFormat.mBytesPerPacket = 0;
audioFormat.mBytesPerFrame = 0;
audioFormat.mFramesPerPacket = 1024;
audioFormat.mBitsPerChannel = 0;
audioFormat.mReserved = 0;
return audioFormat;
}
O loop de renderização
OSStatus err;
ExtAudioFileRef outFile;
NSURL *mixdownURL = [NSURL fileURLWithPath:filePath isDirectory:NO];
// internal data format
AudioStreamBasicDescription localFormat = AUCanonicalASBD(44100.0, 2);
// output file format
AudioStreamBasicDescription mixdownFormat = MixdownAAC();
err = ExtAudioFileCreateWithURL((CFURLRef)mixdownURL,
kAudioFileM4AType,
&mixdownFormat,
NULL,
kAudioFileFlags_EraseFile,
&outFile);
err = ExtAudioFileSetProperty(outFile, kExtAudioFileProperty_ClientDataFormat, sizeof(AudioStreamBasicDescription), &localFormat);
// prep
AllRenderData *allData = &allRenderData;
writeBuffer = malloc(sizeof(AudioBufferList) + (2*sizeof(AudioBuffer)));
writeBuffer->mNumberBuffers = 2;
writeBuffer->mBuffers[0].mNumberChannels = 1;
writeBuffer->mBuffers[0].mDataByteSize = bufferBytes;
writeBuffer->mBuffers[0].mData = malloc(bufferBytes);
writeBuffer->mBuffers[1].mNumberChannels = 1;
writeBuffer->mBuffers[1].mDataByteSize = bufferBytes;
writeBuffer->mBuffers[1].mData = malloc(bufferBytes);
memset(writeBuffer->mBuffers[0].mData, 0, bufferBytes);
memset(writeBuffer->mBuffers[1].mData, 0, bufferBytes);
UInt32 framesToGet;
UInt32 frameCount = allData->gLoopStartFrame;
UInt32 startFrame = allData->gLoopStartFrame;
UInt32 lastFrame = allData->gLoopEndFrame;
// write one silent buffer
ExtAudioFileWrite(outFile, bufferFrames, writeBuffer);
while (frameCount < lastFrame){
// how many frames do we need to get
if (lastFrame - frameCount > bufferFrames)
framesToGet = bufferFrames;
else
framesToGet = lastFrame - frameCount;
// get dem frames
err = theBigOlCallback((void*)&allRenderData,
NULL, NULL, 1,
framesToGet, writeBuffer);
// write to output file
ExtAudioFileWrite(outFile, framesToGet, writeBuffer);
frameCount += framesToGet;
}
// write one trailing silent buffer
memset(writeBuffer->mBuffers[0].mData, 0, bufferBytes);
memset(writeBuffer->mBuffers[1].mData, 0, bufferBytes);
processLimiterInPlace8p24(limiter, writeBuffer->mBuffers[0].mData, writeBuffer->mBuffers[1].mData, bufferFrames);
ExtAudioFileWrite(outFile, bufferFrames, writeBuffer);
err = ExtAudioFileDispose(outFile);
Os quadros do pcm foram criados corretamente, mas o ExtAudioFileWrite falha na segunda / terceira vez em que é chamad
Alguma ideia? Obrigado