Minimal CoreAudio line in example

line-in.cc

#include <CoreAudio/CoreAudio.h>
#include <AudioToolbox/AudioToolbox.h>

#include <iostream>

static const int kNumberBuffers = 3;
static const int kBufferByteSize = 8192;

void callback (void *userData, AudioQueueRef queue, AudioQueueBufferRef buffer, const AudioTimeStamp *startTime, UInt32 inumberPacketDescriptions, const AudioStreamPacketDescription *packetDescs) {
  OSStatus status;

  std::cout << buffer->mAudioDataBytesCapacity << std::endl;

  status = AudioQueueEnqueueBuffer(queue, buffer, 0, nullptr);
  if (status != 0) exit(5);
}

int main() {
  OSStatus status;
  AudioStreamBasicDescription desc;

  desc.mSampleRate = 44100;
  desc.mFormatID = kAudioFormatLinearPCM;
  desc.mFormatFlags = kAudioFormatFlagIsSignedInteger;
  desc.mBytesPerPacket = 0;
  desc.mFramesPerPacket = 1;
  desc.mBytesPerFrame = 0;
  desc.mChannelsPerFrame = 2;
  desc.mBitsPerChannel = 16;
  desc.mReserved = 0;

  AudioQueueRef queue;
  status = AudioQueueNewInput(&desc, callback, nullptr, nullptr, nullptr, 0, &queue);
  if (status != 0) return 1;

  status = AudioQueueStart(queue, nullptr);
  if (status != 0) return 2;

  for (int i = 0; i < kNumberBuffers; ++i) {
    AudioQueueBufferRef buffer;

    status = AudioQueueAllocateBuffer(queue, kBufferByteSize, &buffer);
    if (status != 0) return 3;

    status = AudioQueueEnqueueBuffer(queue, buffer, 0, nullptr);
    if (status != 0) return 4;
  }

  getchar();

  return 0;
}

Makefile

line-in:
	clang++ darwin.cc -framework AudioToolBox -framework CoreFoundation -o line-in

This gives [aqme] 318: error -66680 finding/initializing AQDefaultInput