Receiving kAUGraphErr_CannotDoInCurrentContext

Question

The line AudioDeviceManager *manager = (__bridge AudioDeviceManager *)inRefCon; is causing an EXC_BAD_ACCESS (code 1). The actual error is AudioUnitRender Failed: Unknown (-10863), which translates into kAUGraphErr_CannotDoInCurrentContext.

Here's the callback where it's happening:

static OSStatus playbackCallback(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData) {  

    int i, j; 


    if(startedCallback && noInterrupt) {


    //get a copy of the objectiveC class "self"
    AudioDeviceManager *manager = (__bridge AudioDeviceManager *)inRefCon;

    //data from input; 16 bit integer, one channel
    short signed int * source= (short signed int *)bufferList->mBuffers[0].mData; 

    inNumberFrames= inNumberFrames<1025?inNumberFrames:1024; 

    //pre created data stores   
    float * inputbuf = manager->inputbuf; 

    // shift old audio data
    memmove(inputbuf, inputbuf+inNumberFrames, sizeof(float)*(1024-inNumberFrames));

    for (j = 0; j < inNumberFrames; j++) {
        inputbuf[j+1024-inNumberFrames] = source[j]*3.0518509475997e-05f; //conversion from 16 bit integer (range up to 32767 either side of 0.0) to float (-1.0 to 1.0)
    }

    manager->seq_cb(inputbuf, NULL, inNumberFrames, inTimeStamp, manager->seq);

    //loop through all the buffers that need to be filled ( in practice, will be one) 
    for (i = 0 ; i < ioData->mNumberBuffers; i++){

        //get the buffer to be filled
        AudioBuffer buffer = ioData->mBuffers[i];
        //printf("which buf %d numberOfSamples %d channels %d countertest %d \n", i, buffer.mDataByteSize, buffer.mNumberChannels, g_countertest);

        //if needed we can get the number of bytes that will fill the buffer using
        // int numberOfSamples = ioData->mBuffers[i].mDataByteSize;

        //get the buffer and point to it as an UInt32 (as we will be filling it with 32 bit samples)
        //if we wanted we could grab it as a 16 bit and put in the samples for left and right seperately
        //but the loop below would be for(j = 0; j < inNumberFrames * 2; j++) as each frame is a 32 bit number
        //UInt32 *frameBuffer = buffer.mData;

        short signed int *frameBuffer = (short signed int *)buffer.mData;


        //loop through the buffer and fill the frames
        for (j = 0; j < inNumberFrames; j++){

            //interleaved stereo, left then right
            frameBuffer[2*j] = 0;       //mono output; later could have stereo effects
            frameBuffer[2*j+1] = 0; 

            //++g_countertest; 
        }
    }


    } else {

        //output zeroes while not ready to process input

        for (i = 0 ; i < ioData->mNumberBuffers; i++){
            AudioBuffer buffer = ioData->mBuffers[i];

            short signed int *frameBuffer = (short signed int *)buffer.mData;

            //loop through the buffer and fill the frames
            for (j = 0; j < inNumberFrames; j++){

                short signed int value = 0; //32767.0*0.0; 
                frameBuffer[2*j] = value;   
                frameBuffer[2*j+1] = value; 

                //++g_countertest; 
            }

        }

    }
    return noErr;
}

I've found this, which is a similar situation. The documentation just says

you can generally attempt the action again - typically the NEXT render cycle

but every time the callback gets called the same exception is raised.

Stack trace:

Thread 6 name:  AURemoteIO::IOThread
Thread 6 Crashed:
0   libobjc.A.dylib                 0x317bcf7a objc_retain + 10
1   Partyscape                      0x0006cb36 _ZL16playbackCallbackPvPmPK14AudioTimeStampmmP15AudioBufferList (AudioDeviceManager.mm:80)
2   AudioToolbox                    0x366a5326 AUInputElement::PullInput(unsigned long&, AudioTimeStamp const&, unsigned long, unsigned long) + 130
3   AudioToolbox                    0x366aa6f6 AUInputFormatConverter2::InputProc(OpaqueAudioConverter*, unsigned long*, AudioBufferList*, AudioStreamPacketDescription**, void*) + 154
4   AudioToolbox                    0x3668f31e AudioConverterChain::CallInputProc(unsigned long) + 354
5   AudioToolbox                    0x3668f074 AudioConverterChain::FillBufferFromInputProc(unsigned long*, CABufferList*) + 72
6   AudioToolbox                    0x3668f01e BufferedAudioConverter::GetInputBytes(unsigned long, unsigned long&, CABufferList const*&) + 122
7   AudioToolbox                    0x366aa5c2 CBRConverter::RenderOutput(CABufferList*, unsigned long, unsigned long&, AudioStreamPacketDescription*) + 74
8   AudioToolbox                    0x3668ed4c BufferedAudioConverter::FillBuffer(unsigned long&, AudioBufferList&, AudioStreamPacketDescription*) + 180
9   AudioToolbox                    0x3668ee92 AudioConverterChain::RenderOutput(CABufferList*, unsigned long, unsigned long&, AudioStreamPacketDescription*) + 86
10  AudioToolbox                    0x3668ed4c BufferedAudioConverter::FillBuffer(unsigned long&, AudioBufferList&, AudioStreamPacketDescription*) + 180
11  AudioToolbox                    0x3668eb22 AudioConverterFillComplexBuffer + 350
12  AudioToolbox                    0x367549b0 AUInputFormatConverter2::PullAndConvertInput(AudioTimeStamp const&, unsigned long&, AudioBufferList&, AudioStreamPacketDescription*, bool&) + 104
13  AudioToolbox                    0x366aa518 AUConverterBase::RenderBus(unsigned long&, AudioTimeStamp const&, unsigned long, unsigned long) + 896
14  AudioToolbox                    0x36745376 AURemoteIO::RenderBus(unsigned long&, AudioTimeStamp const&, unsigned long, unsigned long) + 42
15  AudioToolbox                    0x36757d84 AUBase::DoRenderBus(unsigned long&, AudioTimeStamp const&, unsigned long, AUOutputElement*, unsigned long, AudioBufferList&) + 184
16  AudioToolbox                    0x3669002e AUBase::DoRender(unsigned long&, AudioTimeStamp const&, unsigned long, unsigned long, AudioBufferList&) + 438
17  AudioToolbox                    0x3674592a AURemoteIO::PerformIO(unsigned int, unsigned int, XAudioTimeStamp const&, XAudioTimeStamp const&, int&) + 870
18  AudioToolbox                    0x36745a90 AURIOCallbackReceiver_PerformIO + 192
19  AudioToolbox                    0x3673ca1e _XPerformIO + 178
20  AudioToolbox                    0x366a5cdc mshMIGPerform + 368
21  AudioToolbox                    0x36710b96 MSHMIGDispatchMessage + 22
22  AudioToolbox                    0x367452ea AURemoteIO::IOThread::Run() + 58
23  AudioToolbox                    0x36748f42 AURemoteIO::IOThread::Entry(void*) + 2
24  AudioToolbox                    0x36685c9c CAPThread::Entry(CAPThread*) + 208
25  libsystem_c.dylib               0x3414172e _pthread_start + 314
26  libsystem_c.dylib               0x341415e8 thread_start + 0

In fact there is another AURemoteIO thread, and it looks like this:

Thread 9 name:  AURemoteIO::IOThread
Thread 9:
0   libsystem_kernel.dylib          0x382dd004 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x382dd1fa mach_msg + 50
2   AudioToolbox                    0x36745312 AURemoteIO::IOThread::Run() + 98
3   AudioToolbox                    0x36748f42 AURemoteIO::IOThread::Entry(void*) + 2
4   AudioToolbox                    0x36685c9c CAPThread::Entry(CAPThread*) + 208
5   libsystem_c.dylib               0x3414172e _pthread_start + 314
6   libsystem_c.dylib               0x341415e8 thread_start + 0