OSX audio may be stable, works on 2010 macbook pro

src/CubicSDR.cpp

@@ -51,8 +51,8 @@ bool CubicSDR::OnInit() {
     int main_policy;
     struct sched_param main_param;
 
-    main_policy = SCHED_OTHER;
-    main_param.sched_priority = sched_get_priority_min(SCHED_OTHER);
+    main_policy = SCHED_RR;
+    main_param.sched_priority = sched_get_priority_min(SCHED_RR)+2;
 
     pthread_setschedparam(pthread_self(), main_policy, &main_param);
 #endif

src/CubicSDRDefs.h

@@ -1,6 +1,10 @@
 #pragma once
 
+#ifdef __APPLE__
+#define BUF_SIZE (16384*3)
+#else
 #define BUF_SIZE (16384*4)
+#endif
 #define SRATE 2000000
 #define FFT_SIZE 2048
 

src/audio/AudioThread.cpp

@@ -3,7 +3,7 @@
 #include <vector>
 
 AudioThread::AudioThread(AudioThreadInputQueue *inputQueue) :
-        inputQueue(inputQueue), terminated(false), audio_queue_ptr(0) {
+        inputQueue(inputQueue), terminated(false), audio_queue_ptr(0), underflow_count(0) {
 
 }
 
@@ -16,29 +16,63 @@ static int audioCallback(void *outputBuffer, void *inputBuffer, unsigned int nBu
     AudioThread *src = (AudioThread *) userData;
     float *out = (float*) outputBuffer;
     if (status) {
-        std::cout << "Audio buffer underflow.." << std::endl;
+        std::cout << "Audio buffer underflow.." << (src->underflow_count++) << std::endl;
     }
-    if (!src->audio_queue.size()) {
+
+    std::queue<std::vector<float> > *audio_queue = src->audio_queue.load();
+
+#ifdef __APPLE__	// Crude re-sync
+    int wait_for_it = 0;
+
+    if (audio_queue->empty()) {
+		while (wait_for_it++ < 50) {	// Can we wait it out?
+			std::this_thread::sleep_for(std::chrono::microseconds(10000));
+//    		std::this_thread::yield();
+			if (!audio_queue->empty()) {
+				std::cout << "Buffer recovery.." << std::endl;
+				break;
+			}
+		}
+    }
+#endif
+
+    if (audio_queue->empty()) {
         for (int i = 0; i < nBufferFrames * 2; i++) {
             out[i] = 0;
         }
         return 0;
     }
-    std::vector<float> nextBuffer = src->audio_queue.front();
+
+    wait_for_it = 0;
+
+    std::vector<float> nextBuffer = audio_queue->front();
+    int nextBufferSize = nextBuffer.size();
     for (int i = 0; i < nBufferFrames * 2; i++) {
         out[i] = nextBuffer[src->audio_queue_ptr];
         src->audio_queue_ptr++;
-        if (src->audio_queue_ptr == nextBuffer.size()) {
-            src->audio_queue.pop();
+        if (src->audio_queue_ptr == nextBufferSize) {
+            audio_queue->pop();
             src->audio_queue_ptr = 0;
-            if (!src->audio_queue.size()) {
-                for (int j = i; j < nBufferFrames * 2; j++) {
-                    std::cout << "Audio buffer underflow.." << std::endl;
-                    out[i] = 0;
-                }
-                return 0;
+            if (audio_queue->empty()) {
+
+#ifdef __APPLE__
+            	while (wait_for_it++ < 50) {	// Can we wait it out?
+        			std::this_thread::sleep_for(std::chrono::microseconds(10000));
+            		if (!audio_queue->empty()) {
+        				std::cout << "Buffer recovery.." << std::endl;
+            			break;
+            		}
+            	}
+#endif
+            	if (audio_queue->empty()) {
+					for (int j = i; j < nBufferFrames * 2; j++) {
+						std::cout << "Audio buffer underflow mid request.."	<< (src->underflow_count++) << std::endl;
+						out[i] = 0;
+					}
+					return 0;
+				}
             }
-            nextBuffer = src->audio_queue.front();
+            nextBuffer = audio_queue->front();
         }
     }
     return 0;
@@ -57,12 +91,15 @@ void AudioThread::threadMain() {
     parameters.nChannels = 2;
     parameters.firstChannel = 0;
     unsigned int sampleRate = AUDIO_FREQUENCY;
-    unsigned int bufferFrames = 256;
+    unsigned int bufferFrames = 0;
 
     RtAudio::StreamOptions opts;
-    opts.flags = RTAUDIO_MINIMIZE_LATENCY | RTAUDIO_SCHEDULE_REALTIME;
+//    opts.flags =  RTAUDIO_SCHEDULE_REALTIME | RTAUDIO_MINIMIZE_LATENCY;
+//    opts.flags = RTAUDIO_MINIMIZE_LATENCY;
     opts.streamName = "CubicSDR Audio Output";
-    opts.priority = 0;
+    opts.priority = sched_get_priority_max(SCHED_FIFO);
+
+    audio_queue = new std::queue<std::vector<float> >;
 
     try {
         dac.openStream(&parameters, NULL, RTAUDIO_FLOAT32, sampleRate, &bufferFrames, &audioCallback, (void *) this, &opts);
@@ -74,10 +111,11 @@ void AudioThread::threadMain() {
 
     while (!terminated) {
         AudioThreadInput inp;
-        inputQueue->pop(inp);
-        if (inp.data.size()) {
-            audio_queue.push(inp.data);
-        }
+		inputQueue->pop(inp);
+		if (inp.data.size()) {
+			audio_queue.load()->push(inp.data);
+		}
+//        std::this_thread::yield();
     }
 
     try {

src/audio/AudioThread.h

@@ -28,8 +28,9 @@ typedef ThreadQueue<AudioThreadInput> AudioThreadInputQueue;
 
 class AudioThread {
 public:
-    std::queue<std::vector<float> > audio_queue;
-    unsigned int audio_queue_ptr;
+    std::atomic< std::queue<std::vector<float> > *> audio_queue;
+    std::atomic<unsigned int> audio_queue_ptr;
+    std::atomic<unsigned int> underflow_count;
 
     AudioThread(AudioThreadInputQueue *inputQueue);
     ~AudioThread();