Added a realtime loudness reading to fixed term meter

Author: maxwalley

include/FixedTermLoudnessMeter.h

@@ -3,6 +3,7 @@
 #include <chrono>
 #include <cmath>
 #include <span>
+#include <mutex>
 
 #include "LiblufsAPI.h"
 #include "DoubleBuffer.h"
@@ -25,7 +26,10 @@ class LIBLUFS_API FixedTermLoudnessMeter
     //This is not threadsafe with process calls
     void reset();
 
-    //This is threadsafe with process calls, but must only be called from a single thread at a time
+    //This can only be called from the same thread as the process calls
+    float getLoudnessRealtime();
+
+    //This is threadsafe with process calls
     float getLoudness() const;
 
 private:
@@ -37,6 +41,7 @@ class LIBLUFS_API FixedTermLoudnessMeter
     const int blockLengthSamples;
     const float min;
 
+    mutable std::mutex channelProcessorsOfflineLock;
     DoubleBuffer<std::vector<ChannelProcessor>> channelProcessors;
 
     size_t blockWritePos = 0;

src/FixedTermLoudnessMeter.cpp

@@ -68,8 +68,33 @@ void FixedTermLoudnessMeter::reset()
     blockWritePos = 0;
 }
 
+float FixedTermLoudnessMeter::getLoudnessRealtime()
+{
+    const std::vector<ChannelProcessor>& processors = channelProcessors.realtimeAquire();
+
+    float accumulatedChannels = 0.0f;
+
+    std::for_each(processors.begin(), processors.end(), [&accumulatedChannels](const ChannelProcessor& processor)
+    {
+        accumulatedChannels += processor.getCurrentBlockMeanSquares() * processor.getWeighting();
+    });
+
+    if(accumulatedChannels == 0.0f)
+    {
+        return min;
+    }
+
+    float loudness = -0.691f + 10.0f * std::log10(accumulatedChannels);
+
+    channelProcessors.realtimeRelease();
+
+    return loudness;
+}
+
 float FixedTermLoudnessMeter::getLoudness() const
 {
+    std::scoped_lock<std::mutex> lock{channelProcessorsOfflineLock};
+
     const std::vector<ChannelProcessor>& processors = channelProcessors.nonRealtimeRead();
 
     float accumulatedChannels = 0.0f;