Ограничение размера звукового буфера

Question

В настоящее время я использую скрипт Apple «iPhoneMixerEQGraphTest» для воспроизведения аудио в моем приложении, однако они не «буферизуют», они посылают все данные в буфер сразу, что, по моему мнению, вызывает мое приложение для перегрузки. Я получаю память более 100 МБ, а затем сбой. Обычно память составляет менее 20 МБ. Как бы я мог вызвать звук, чтобы читать только буферную часть аудио, а не все. Авария происходит при обратном вызове: memcpy(out, &in[sample], ioData->mBuffers[0].mDataByteSize);.

загружаю мой звук с помощью этого метода:

- (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); 
    } 
} 

Она 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 обратный вызов 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; 
} 

Answer 1

Не читать весь аудиофайл сразу. Вместо этого, читайте только несколько секунд за раз в круговой буфер или fifo и продолжайте заполнять буфер из файла (в другом потоке), чтобы в точности поддерживать скорость, с которой обратный вызов звуковой визуализации опорожняет его. Память, требуемая для буфера, может быть довольно маленькой (возможно, на несколько секунд или даже меньше, чтобы быть в безопасности).

Другой альтернативой является карта памяти всего файла (mmap), которая не загрязняет память, и, таким образом, не учитывает причитаемый объем памяти приложений (пока он не приблизится к диапазону гигабайт).