add audio starvation detection

interface/src/Audio.cpp

@@ -124,7 +124,7 @@ Audio::Audio(QObject* parent) :
     _audioOutputMsecsUnplayedStats(1, FRAMES_AVAILABLE_STATS_WINDOW_SECONDS),
     _lastSentAudioPacket(0),
     _packetSentTimeGaps(1, APPROXIMATELY_30_SECONDS_OF_AUDIO_PACKETS),
-    _audioOutputIODevice(_receivedAudioStream)
+    _audioOutputIODevice(_receivedAudioStream, this)
 {
     // clear the array of locally injected samples
     memset(_localProceduralSamples, 0, NETWORK_BUFFER_LENGTH_BYTES_PER_CHANNEL);
@@ -1823,6 +1823,16 @@ bool Audio::switchInputToAudioDevice(const QAudioDeviceInfo& inputDeviceInfo) {
     return supportedFormat;
 }
 
+void Audio::outputNotify() {
+    int recentUnfulfilled = _audioOutputIODevice.getRecentUnfulfilledReads();
+    if (recentUnfulfilled > 0) {
+        qDebug() << "WARNING --- WE HAD at least:" << recentUnfulfilled << "recently unfulfilled readData() calls";
+
+        // TODO: Ryan Huffman -- add code here to increase the AUDIO_OUTPUT_BUFFER_SIZE_FRAMES... this code only
+        // runs in cases where the audio device requested data samples, and ran dry because we couldn't fulfill the request
+    }
+}
+
 bool Audio::switchOutputToAudioDevice(const QAudioDeviceInfo& outputDeviceInfo) {
     bool supportedFormat = false;
 
@@ -1856,6 +1866,8 @@ bool Audio::switchOutputToAudioDevice(const QAudioDeviceInfo& outputDeviceInfo)
 
             // setup our general output device for audio-mixer audio
             _audioOutput = new QAudioOutput(outputDeviceInfo, _outputFormat, this);
+            connect(_audioOutput, &QAudioOutput::notify, this, &Audio::outputNotify);
+
             _audioOutput->setBufferSize(AUDIO_OUTPUT_BUFFER_SIZE_FRAMES * _outputFrameSize * sizeof(int16_t));
             qDebug() << "Output Buffer capacity in frames: " << _audioOutput->bufferSize() / sizeof(int16_t) / (float)_outputFrameSize;
             
@@ -1934,6 +1946,7 @@ qint64 Audio::AudioOutputIODevice::readData(char * data, qint64 maxSize) {
     int samplesRequested = maxSize / sizeof(int16_t);
     int samplesPopped;
     int bytesWritten;
+    
     if ((samplesPopped = _receivedAudioStream.popSamples(samplesRequested, false)) > 0) {
         AudioRingBuffer::ConstIterator lastPopOutput = _receivedAudioStream.getLastPopOutput();
         lastPopOutput.readSamples((int16_t*)data, samplesPopped);
@@ -1943,5 +1956,10 @@ qint64 Audio::AudioOutputIODevice::readData(char * data, qint64 maxSize) {
         bytesWritten = maxSize;
     }
 
+    int bytesAudioOutputUnplayed = _audio->_audioOutput->bufferSize() - _audio->_audioOutput->bytesFree();
+    if (bytesAudioOutputUnplayed == 0 && bytesWritten == 0) {
+        _unfulfilledReads++;
+    }
+
     return bytesWritten;
 }

interface/src/Audio.h

@@ -72,16 +72,22 @@ public:
 
     class AudioOutputIODevice : public QIODevice {
     public:
-        AudioOutputIODevice(MixedProcessedAudioStream& receivedAudioStream) : _receivedAudioStream(receivedAudioStream) {};
+        AudioOutputIODevice(MixedProcessedAudioStream& receivedAudioStream, Audio* audio) : 
+            _receivedAudioStream(receivedAudioStream), _audio(audio), _unfulfilledReads(0) {};
 
         void start() { open(QIODevice::ReadOnly); }
         void stop() { close(); }
         qint64	readData(char * data, qint64 maxSize);
         qint64	writeData(const char * data, qint64 maxSize) { return 0; }
+        
+        int getRecentUnfulfilledReads() { int unfulfilledReads = _unfulfilledReads; _unfulfilledReads = 0; return unfulfilledReads; }
     private:
         MixedProcessedAudioStream& _receivedAudioStream;
+        Audio* _audio;
+        int _unfulfilledReads;
     };
 
+    friend class AudioOutputIODevice;
 
     // setup for audio I/O
     Audio(QObject* parent = 0);
@@ -170,11 +176,15 @@ public slots:
     const AudioStreamStats& getAudioMixerAvatarStreamAudioStats() const { return _audioMixerAvatarStreamAudioStats; }
     const QHash<QUuid, AudioStreamStats>& getAudioMixerInjectedStreamAudioStatsMap() const { return _audioMixerInjectedStreamAudioStatsMap; }
 
+    void outputNotify();
+
 signals:
     bool muteToggled();
     void preProcessOriginalInboundAudio(unsigned int sampleTime, QByteArray& samples, const QAudioFormat& format);
     void processInboundAudio(unsigned int sampleTime, const QByteArray& samples, const QAudioFormat& format);
     void processLocalAudio(unsigned int sampleTime, const QByteArray& samples, const QAudioFormat& format);
+    
+    
 private:
     void outputFormatChanged();