Segfault on Mac when the audio system is turned off

[geraintluff]

Firstly, I'd like to say thanks for the module. :)

Now the issue: when no audio is played on a Mac for a while, it seems to turn off the audio system or something.

When I attempt to use node-core-audio after this happens (so I'd expect it to turn on again), it segfaults. Here's the stack trace I got from lldb:

* thread #7: tid = 0x51acf6, 0x00007fff98dd21ec libsystem_platform.dylib`_platform_memmove$VARIANT$Nehalem + 524, name = 'com.apple.audio.IOThread.client', stop reason = EXC_BAD_ACCESS (code=1, address=0x1037ffff0)
  * frame #0: 0x00007fff98dd21ec libsystem_platform.dylib`_platform_memmove$VARIANT$Nehalem + 524
    frame #1: 0x0000000100cb341b NodeCoreAudio.node`PaUtil_WriteRingBuffer + 235
    frame #2: 0x0000000100cb2df0 NodeCoreAudio.node`BlioCallback + 144
    frame #3: 0x0000000100cace23 NodeCoreAudio.node`AdaptingProcess + 851
    frame #4: 0x0000000100cac3ea NodeCoreAudio.node`PaUtil_EndBufferProcessing + 442
    frame #5: 0x0000000100cb14e4 NodeCoreAudio.node`AudioIOProc + 1060
    frame #6: 0x0000000104809599 CoreAudio`AUInputElement::PullInput(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) + 177
    frame #7: 0x0000000104808e4f CoreAudio`AUInputFormatConverter2::InputProc(OpaqueAudioConverter*, unsigned int*, AudioBufferList*, AudioStreamPacketDescription**, void*) + 193
    frame #8: 0x00007fff963215e3 AudioToolbox`AudioConverterChain::CallInputProc(unsigned int) + 417
    frame #9: 0x00007fff9632132f AudioToolbox`AudioConverterChain::FillBufferFromInputProc(unsigned int*, CABufferList*) + 125
    frame #10: 0x00007fff96300349 AudioToolbox`BufferedAudioConverter::GetInputBytes(unsigned int, unsigned int&, CABufferList const*&) + 179
    frame #11: 0x00007fff962df0ca AudioToolbox`CBRConverter::RenderOutput(CABufferList*, unsigned int, unsigned int&, AudioStreamPacketDescription*) + 104
    frame #12: 0x00007fff963001d0 AudioToolbox`BufferedAudioConverter::FillBuffer(unsigned int&, AudioBufferList&, AudioStreamPacketDescription*) + 286
    frame #13: 0x00007fff96321147 AudioToolbox`AudioConverterChain::RenderOutput(CABufferList*, unsigned int, unsigned int&, AudioStreamPacketDescription*) + 99
    frame #14: 0x00007fff963001d0 AudioToolbox`BufferedAudioConverter::FillBuffer(unsigned int&, AudioBufferList&, AudioStreamPacketDescription*) + 286
    frame #15: 0x00007fff962de91e AudioToolbox`AudioConverterFillComplexBuffer + 292
    frame #16: 0x0000000104808d06 CoreAudio`AUInputFormatConverter2::PullAndConvertInput(AudioTimeStamp const&, unsigned int&, AudioBufferList&, AudioStreamPacketDescription*, bool&) + 98
    frame #17: 0x00000001048085ea CoreAudio`AUConverterBase::RenderBus(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) + 188
    frame #18: 0x00000001048061c1 CoreAudio`AUBase::DoRenderBus(unsigned int&, AudioTimeStamp const&, unsigned int, AUOutputElement*, unsigned int, AudioBufferList&) + 153
    frame #19: 0x0000000104804a75 CoreAudio`AUBase::DoRender(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int, AudioBufferList&) + 423
    frame #20: 0x000000010480bdd8 CoreAudio`AUHAL::AUIOProc(unsigned int, AudioTimeStamp const*, AudioBufferList const*, AudioTimeStamp const*, AudioBufferList*, AudioTimeStamp const*, void*) + 2076
    frame #21: 0x00007fff8e789acb CoreAudio`HALC_ProxyIOContext::IOWorkLoop() + 3667
    frame #22: 0x00007fff8e788bcd CoreAudio`HALC_ProxyIOContext::IOThreadEntry(void*) + 97
    frame #23: 0x00007fff8e788a8d CoreAudio`HALB_IOThread::Entry(void*) + 75
    frame #24: 0x00007fff9266a899 libsystem_pthread.dylib`_pthread_body + 138
    frame #25: 0x00007fff9266a72a libsystem_pthread.dylib`_pthread_start + 137

[ZECTBynmo]

Oh interesting! I haven't seen this issue before. I'm not sure when I'll get a chance to work, but I bet the audio engine needs to be restarted

[geraintluff]

I might well have mis-diagnosed the cause - turning off the D2A might be coincidental.

However, it seems to consistently have problems the first time I run it in a while, but work fine second time I run the same thing.

[ZECTBynmo]

I'm sorry, I just started a new job so I have 0 time to actually dig into this issue, but I'm happy to help direct your debugging. Are you starting the script fresh after waiting for a while, or is the same audio engine still instantiated from a while ago? What happens if you just create a new audio engine instance (restarting everything) when you try to run after a break?

[geraintluff]

This is starting the script fresh after waiting for a while. I'm afraid I'm not quite sure what you mean by your last sentence.