Merge pull request #8610 from zzmp/test/audio-jitter

add audio jitter simulator testing tool

interface/src/ui/PreferencesDialog.cpp

@@ -278,12 +278,18 @@ void setupPreferences() {
         preferences->addPreference(preference);
     }
 #if DEV_BUILD || PR_BUILD
+    {
+        auto getter = []()->bool { return DependencyManager::get<AudioClient>()->isSimulatingJitter(); };
+        auto setter = [](bool value) { return DependencyManager::get<AudioClient>()->setIsSimulatingJitter(value); };
+        auto preference = new CheckPreference(AUDIO, "Packet jitter simulator", getter, setter);
+        preferences->addPreference(preference);
+    }
     {
         auto getter = []()->float { return DependencyManager::get<AudioClient>()->getGateThreshold(); };
         auto setter = [](float value) { return DependencyManager::get<AudioClient>()->setGateThreshold(value); };
-        auto preference = new SpinnerPreference(AUDIO, "Debug gate threshold", getter, setter);
+        auto preference = new SpinnerPreference(AUDIO, "Packet throttle threshold", getter, setter);
         preference->setMin(1);
-        preference->setMax((float)100);
+        preference->setMax(200);
         preference->setStep(1);
         preferences->addPreference(preference);
     }

libraries/audio-client/src/AudioClient.cpp

@@ -56,8 +56,6 @@ static const int RECEIVED_AUDIO_STREAM_CAPACITY_FRAMES = 100;
 static const auto DEFAULT_POSITION_GETTER = []{ return Vectors::ZERO; };
 static const auto DEFAULT_ORIENTATION_GETTER = [] { return Quaternions::IDENTITY; };
 
-static const int DEFAULT_AUDIO_OUTPUT_GATE_THRESHOLD = 1;
-
 Setting::Handle<bool> dynamicJitterBuffers("dynamicJitterBuffers", DEFAULT_DYNAMIC_JITTER_BUFFERS);
 Setting::Handle<int> maxFramesOverDesired("maxFramesOverDesired", DEFAULT_MAX_FRAMES_OVER_DESIRED);
 Setting::Handle<int> staticDesiredJitterBufferFrames("staticDesiredJitterBufferFrames",
@@ -102,8 +100,7 @@ private:
 
 AudioClient::AudioClient() :
     AbstractAudioInterface(),
-    _gateThreshold("audioOutputGateThreshold", DEFAULT_AUDIO_OUTPUT_GATE_THRESHOLD),
-    _gate(this, _gateThreshold.get()),
+    _gate(this),
     _audioInput(NULL),
     _desiredInputFormat(),
     _inputFormat(),
@@ -551,31 +548,53 @@ void AudioClient::handleAudioDataPacket(QSharedPointer<ReceivedMessage> message)
     }
 }
 
-AudioClient::Gate::Gate(AudioClient* audioClient, int threshold) :
-    _audioClient(audioClient),
-    _threshold(threshold) {}
+AudioClient::Gate::Gate(AudioClient* audioClient) :
+    _audioClient(audioClient) {}
+
+void AudioClient::Gate::setIsSimulatingJitter(bool enable) {
+    std::lock_guard<std::mutex> lock(_mutex);
+    flush();
+    _isSimulatingJitter = enable;
+}
 
 void AudioClient::Gate::setThreshold(int threshold) {
+    std::lock_guard<std::mutex> lock(_mutex);
     flush();
     _threshold = std::max(threshold, 1);
 }
 
 void AudioClient::Gate::insert(QSharedPointer<ReceivedMessage> message) {
+    std::lock_guard<std::mutex> lock(_mutex);
+
     // Short-circuit for normal behavior
-    if (_threshold == 1) {
+    if (_threshold == 1 && !_isSimulatingJitter) {
         _audioClient->_receivedAudioStream.parseData(*message);
         return;
     }
 
+    // Throttle the current packet until the next flush
     _queue.push(message);
     _index++;
 
-    if (_index % _threshold == 0) {
+    // When appropriate, flush all held packets to the received audio stream
+    if (_isSimulatingJitter) {
+        // The JITTER_FLUSH_CHANCE defines the discrete probability density function of jitter (ms),
+        // where f(t) = pow(1 - JITTER_FLUSH_CHANCE, (t / 10) * JITTER_FLUSH_CHANCE
+        // for t (ms) = 10, 20, ... (because typical packet timegap is 10ms),
+        // because there is a JITTER_FLUSH_CHANCE of any packet instigating a flush of all held packets.
+        static const float JITTER_FLUSH_CHANCE = 0.6f;
+        // It is set at 0.6 to give a low chance of spikes (>30ms, 2.56%) so that they are obvious,
+        // but settled within the measured 5s window in audio network stats.
+        if (randFloat() < JITTER_FLUSH_CHANCE) {
+            flush();
+        }
+    } else if (!(_index % _threshold)) {
         flush();
     }
 }
 
 void AudioClient::Gate::flush() {
+    // Send all held packets to the received audio stream to be (eventually) played
     while (!_queue.empty()) {
         _audioClient->_receivedAudioStream.parseData(*_queue.front());
         _queue.pop();

libraries/audio-client/src/AudioClient.h

@@ -132,6 +132,9 @@ public:
     int getOutputStarveDetectionThreshold() { return _outputStarveDetectionThreshold.get(); }
     void setOutputStarveDetectionThreshold(int threshold) { _outputStarveDetectionThreshold.set(threshold); }
 
+    bool isSimulatingJitter() { return _gate.isSimulatingJitter(); }
+    void setIsSimulatingJitter(bool enable) { _gate.setIsSimulatingJitter(enable); }
+
     int getGateThreshold() { return _gate.getThreshold(); }
     void setGateThreshold(int threshold) { _gate.setThreshold(threshold); }
 
@@ -230,7 +233,10 @@ private:
 
     class Gate {
     public:
-        Gate(AudioClient* audioClient, int threshold);
+        Gate(AudioClient* audioClient);
+
+        bool isSimulatingJitter() { return _isSimulatingJitter; }
+        void setIsSimulatingJitter(bool enable);
 
         int getThreshold() { return _threshold; }
         void setThreshold(int threshold);
@@ -242,11 +248,13 @@ private:
 
         AudioClient* _audioClient;
         std::queue<QSharedPointer<ReceivedMessage>> _queue;
+        std::mutex _mutex;
+
         int _index{ 0 };
-        int _threshold;
+        int _threshold{ 1 };
+        bool _isSimulatingJitter{ false };
     };
 
-    Setting::Handle<int> _gateThreshold;
     Gate _gate;
 
     Mutex _injectorsMutex;