整理代码

video/core/FrameSynchronizer.cpp

@@ -0,0 +1,111 @@
+/*
+ *******************************************************************************
+ *                                   INCLUDE
+ *******************************************************************************
+ */
+#include "FrameSynchronizer.h"
+#include "util/Math.h"
+#include <thread>
+#include <iostream>
+
+namespace Video
+{
+namespace Core
+{
+/*
+ *******************************************************************************
+ *                                CLASS DEFINE
+ *******************************************************************************
+ */
+FrameSynchronizer::DriftPredictor::DriftPredictor(size_t windowSize): _windowSize(windowSize), _lastPrediction(0)
+{
+}
+
+void FrameSynchronizer::DriftPredictor::update(int64_t drift)
+{
+    _samples.push_back(drift);
+
+    if (_samples.size() > _windowSize)
+        _samples.pop_front();
+
+    constexpr double alpha = 0.2;
+    _lastPrediction        = alpha * drift + (1 - alpha) * _lastPrediction;
+}
+
+int64_t FrameSynchronizer::DriftPredictor::predict()
+{
+    if (_samples.empty())
+        return _lastPrediction;
+
+    if (_samples.size() < 5)
+        return _lastPrediction;
+
+    double sum = 0;
+    for (auto v : _samples)
+        sum += v;
+    double mean = sum / _samples.size();
+
+    constexpr int64_t MAX_DRIFT = 30000;
+
+    int64_t result = static_cast<int64_t>(0.7 * mean + 0.3 * _lastPrediction);
+    return Util::Math::clamp(result, -MAX_DRIFT, MAX_DRIFT);
+}
+
+void FrameSynchronizer::DriftPredictor::reset()
+{
+    _samples.clear();
+    _lastPrediction = 0;
+}
+
+/*
+ *******************************************************************************
+ *                                CLASS DEFINE
+ *******************************************************************************
+ */
+FrameSynchronizer::FrameSynchronizer(const std::string& name): _name(name), _baseClock(0), _lastSysTS(0)
+{
+    _predictor.reset();
+}
+
+FrameSynchronizer::~FrameSynchronizer()
+{
+}
+
+void FrameSynchronizer::reset()
+{
+    _baseClock = 0;
+    _lastSysTS = 0;
+    _predictor.reset();
+}
+
+void FrameSynchronizer::syncFrame(uint64_t frameTS)
+{
+    const uint64_t now = System::timestamp();
+
+    if (_baseClock == 0)
+    {
+        _baseClock = now - frameTS;
+        _lastSysTS = now;
+        return;
+    }
+
+    uint64_t ts = frameTS + _baseClock;
+    if (ts + 500000 < _lastSysTS || ts > _lastSysTS + 10000000)
+    {
+        _predictor.reset();
+        _baseClock = now - frameTS;
+        _lastSysTS = now;
+        return;
+    }
+
+    const uint64_t targetTime = frameTS + _baseClock + _predictor.predict();
+    int64_t        waitTime   = static_cast<int64_t>(targetTime) - static_cast<int64_t>(now);
+    if (waitTime > 0)
+        std::this_thread::sleep_for(std::chrono::microseconds(waitTime));
+
+    const uint64_t actualTime = System::timestamp();
+    _predictor.update(static_cast<int64_t>(actualTime - targetTime));
+    _lastSysTS = actualTime;
+}
+}
+}